M20 Air/Oil separator

[Jay Honeck]

Atlas just got his oil/air separator installed today. (For those who may
not know, Atlas is our '74 Cherokee Pathfinder, so-named because he can lift
literally anything we can fit inside!)

We picked this new accessory up at OSH '04, after much debate. (It's a
helluva lot of money for what looks like a welded tin can.) The clincher
(besides the nice clean belly) is that I'll be able to run a full 12 quarts
of oil in our Lycoming O-540, rather than the 8.5 quarts we could hold
before. (Atlas would puke out the four extra quarts, if added.)

It seems logical to assume that more oil in the engine equals cleaner oil to
all engine parts, at all times. This seems like a very good thing, indeed.

Anyone else got one of these things? Are there any "gotchas" to watch out
for, or are they as bullet-proof as they seem?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination

[Kyle Boatright]

Jay,

Doesn't the air/oil separator simply catch the oil the engine pukes, so the
oil doesn't end up on the belly? If that's the case, your separator better
have a capacity of almost 4 quarts, 'cause I suspect the engine is still
gonna send the first 3.5 quarts out the breather.

KB

"Jay Honeck" > wrote in message
news:CyfTc.304529$XM6.124022@attbi_s53...
> Atlas just got his oil/air separator installed today. (For those who may
> not know, Atlas is our '74 Cherokee Pathfinder, so-named because he can
lift
> literally anything we can fit inside!)
>
> We picked this new accessory up at OSH '04, after much debate. (It's a
> helluva lot of money for what looks like a welded tin can.) The clincher
> (besides the nice clean belly) is that I'll be able to run a full 12
quarts
> of oil in our Lycoming O-540, rather than the 8.5 quarts we could hold
> before. (Atlas would puke out the four extra quarts, if added.)
>
> It seems logical to assume that more oil in the engine equals cleaner oil
to
> all engine parts, at all times. This seems like a very good thing,
indeed.
>
> Anyone else got one of these things? Are there any "gotchas" to watch out
> for, or are they as bullet-proof as they seem?
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination
>
>

[Jay Honeck]

> Doesn't the air/oil separator simply catch the oil the engine pukes, so
the
> oil doesn't end up on the belly? If that's the case, your separator
better
> have a capacity of almost 4 quarts, 'cause I suspect the engine is still
> gonna send the first 3.5 quarts out the breather.

Yes and no.

It constantly feeds the puked out oil back into the crankcase, so you can
run with a full crankcase instead of one that is 1/3 empty.

I'm no mechanic, but more fresh oil sounds good for my engine.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[JJS]

From what I've read here on Rec. Av. * the downside to these oil
separators is that they may also return the moisture, acids, and other
products of combustion that volatilize and go out the breather tube,
back to your crankcase. If you've had oil analysis done in the past I
would certainly be interested if this seems to be the case.

Joe Schneider
8437R

"Jay Honeck" > wrote in message
news:XUnTc.150507$eM2.144868@attbi_s51...
> > Doesn't the air/oil separator simply catch the oil the engine
pukes, so
> the
> > oil doesn't end up on the belly? If that's the case, your
separator
> better
> > have a capacity of almost 4 quarts, 'cause I suspect the engine is
still
> > gonna send the first 3.5 quarts out the breather.
>
> Yes and no.
>
> It constantly feeds the puked out oil back into the crankcase, so
you can
> run with a full crankcase instead of one that is 1/3 empty.
>
> I'm no mechanic, but more fresh oil sounds good for my engine.
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
>

[Doug Vetter]

Jay Honeck wrote:
> Atlas just got his oil/air separator installed today. (For those who may
> not know, Atlas is our '74 Cherokee Pathfinder, so-named because he can lift
> literally anything we can fit inside!)
<snip>
> Anyone else got one of these things? Are there any "gotchas" to watch out
> for, or are they as bullet-proof as they seem?

Hi Jay,

A few comments.

Air/Oil Separators do seem to perform their intended function with a
minimum of problems (when installed correctly, anyway), but my mechanic
recommended I NOT install one because they return moisture to the case
that would normally be vented overboard with the oil vapor. The
long-term effect is reportedly the same as if you were to run the engine
for short periods without attaining the operating temperature required
to boil off the water -- namely, corrosion.

There is also something to be said, IMHO, for adding oil between oil
changes. Oil breaks down over time, and throwing in a quart every 5-10
hours replenishes the anti-wear/anti-corrosion additives as well as
increases the oil's natural ability to hold contaminants in suspension.

Also, I have found no hard evidence that keeping the oil topped vs. 1 or
2 quarts down provides any additional cooling or anti-wear properties.
If we keep our 172's O-360 between 6 and 7 quarts (max 8), our belly
remains reasonably clean and it runs at what I'd call "nominal"
temperature.

This is no surprise, really, as the O-360 certainly doesn't *need* six
or eight quarts of oil. I know of one application (the Seminole) in
which it is certified to run on as little as 2 quarts. I'm sure other
Lycoming engines such as your O-540 are the same in this regard. As
long as you maintain the minimum required oil level, a couple quarts
down isn't going to make any difference except on a LONG ferry flight
where you can't add oil in flight. Most POH's seem to reflect this
(e.g. "Top off for extended flight").

Lastly, FWIW, my partner's other airplane (a 182) has a M20 installed.
Yes, its belly is largely free of oil residue, but it still seems to
acquire a dry, chaulky residue in any case. It looks and feels like
something you'd find just aft of an exhaust stack, and may very well
result from the exhaust...I don't know for sure. But, I do know that
the belly is still dirty enough after 50 hours that I have an
overwhelming desire to break out the creeper and WD40, so I'm convinced
an oil separator would save me no labor. :-)

Safe flying,

-Doug

--
--------------------
Doug Vetter, CFIMEIA

http://www.dvcfi.com
--------------------

[GaryP]

Jay,
I installed one of Bill Sandmans M20s on my Navion back in 2001.
Even
with a worn out set of Continental jugs and high blow-by my belly
cleaned
up almost completely. The engine was majored last spring and now the
belly is spotless even with a full 10qts in the pan. Made a big
difference
in my case and I'm satisfied with the performance of the little
critter.
Since my E225 engine runs hot I doubt that any condensation could
survive
after a flight of any length. Condensation and the sludge buildup
that
would result was my main concern since the M20 is not dis-assembleable
for
cleaning like the Walker/Air Wolf unit. At each annual I soak it in
AvGas
and then blow it out with compressed air. So far so good.

At the time I bought my M20 Walker had ceased building their unit
and
Air Wolf had not purchased the rights to it. I have an Air Wolf Oil
filter
kit on my plane and was very satisfied with their quality/value. If
Air Wolf had announced their intent to build and sell the Walker
design I probably would have waited and bought the larger Walker unit
specifically because of the cleaning issue. But I am satisfied with
my M20 and don't regret buying it.

GaryP

"Jay Honeck" > wrote in message news:<CyfTc.304529$XM6.124022@attbi_s53>...
> Atlas just got his oil/air separator installed today. (For those who may
> not know, Atlas is our '74 Cherokee Pathfinder, so-named because he can lift
> literally anything we can fit inside!)
>
> We picked this new accessory up at OSH '04, after much debate. (It's a
> helluva lot of money for what looks like a welded tin can.) The clincher
> (besides the nice clean belly) is that I'll be able to run a full 12 quarts
> of oil in our Lycoming O-540, rather than the 8.5 quarts we could hold
> before. (Atlas would puke out the four extra quarts, if added.)
>
> It seems logical to assume that more oil in the engine equals cleaner oil to
> all engine parts, at all times. This seems like a very good thing, indeed.
>
> Anyone else got one of these things? Are there any "gotchas" to watch out
> for, or are they as bullet-proof as they seem?

[Frank Stutzman]

GaryP > wrote:
> I installed one of Bill Sandmans M20s on my Navion back in 2001.

[ snip ]
> Since my E225 engine runs hot I doubt that any condensation could
> survive
> after a flight of any length.

Gary, don't you have a wet vaccuum pump on your E-225?

AFAIK the M20 seperators only work for the breather line OR the vaccuum
pump, but not both. To get both areas covered you would have to install
two of them. The walker (air wolf) unit handles both oil sources in one
unit.

(as an aside, you happen to know that the fuel flow is supposed to be at
full throttle for an E-225 do you?)

--
Frank Stutzman
Bonanza N494B "Hula Girl" (Also E-225 powered)
Hood River, OR

[Rip]

I have a wet pump on my Navion, and in fact my plane was used by M20 to
develop their wet pump separator (you can see photos on their website).
Currently, I'm using an Airwolf/Walker. One unit handles both the pump
and the breather, and as Gary mentioned, you can open it for cleaning.
The M20 unit never really worked very well on the vac pump. The Airwolf
unit works perfectly.

Frank Stutzman wrote:
> GaryP > wrote:
>
>> I installed one of Bill Sandmans M20s on my Navion back in 2001.
>
>
> [ snip ]
>
>>Since my E225 engine runs hot I doubt that any condensation could
>>survive
>>after a flight of any length.
>
>
> Gary, don't you have a wet vaccuum pump on your E-225?
>
> AFAIK the M20 seperators only work for the breather line OR the vaccuum
> pump, but not both. To get both areas covered you would have to install
> two of them. The walker (air wolf) unit handles both oil sources in one
> unit.
>
> (as an aside, you happen to know that the fuel flow is supposed to be at
> full throttle for an E-225 do you?)
>
> --
> Frank Stutzman
> Bonanza N494B "Hula Girl" (Also E-225 powered)
> Hood River, OR
>

[GaryP]

Frank Stutzman > wrote in message >...

> Gary, don't you have a wet vaccuum pump on your E-225?

No, I have a SigmaTek dry pump. Probably the most durable dry
pump going as it has aluminum vanes not the usual graphite.

> (as an aside, you happen to know that the fuel flow is supposed to be at
> full throttle for an E-225 do you?)

My engine is fuel injected, technically refered to as an E225-4I. My TO
fuel flow is ~18gph which seems too low for a 470CDI engine. But the fuel
servo was checked and verified as set to manufacturers specs. CHTs hover
around 400F at TO and drop down to about 375F at cruise.

Gary P

[Jay Honeck]

> Air/Oil Separators do seem to perform their intended function with a
> minimum of problems (when installed correctly, anyway), but my mechanic
> recommended I NOT install one because they return moisture to the case
> that would normally be vented overboard with the oil vapor. The
> long-term effect is reportedly the same as if you were to run the engine
> for short periods without attaining the operating temperature required
> to boil off the water -- namely, corrosion.

Thanks for the comments, Doug. I had not heard this, and my mechanic did not
mention it, but I suppose it makes some sense.

On the other hand, since I fly every few days, I find it hard to imagine
that moisture could build up (or even survive) a flight with CHTs in the 350
degree range, and EGTs in the 1500 degree range!

> There is also something to be said, IMHO, for adding oil between oil
> changes. Oil breaks down over time, and throwing in a quart every 5-10
> hours replenishes the anti-wear/anti-corrosion additives as well as
> increases the oil's natural ability to hold contaminants in suspension.

Well, I change my oil around 25 hours minimum, 50 hours maximum. Hopefully
the billion-dollar-a-quart semi-synthetic Aeroshell oil holds together at
least THAT long before breaking down?

> Also, I have found no hard evidence that keeping the oil topped vs. 1 or
> 2 quarts down provides any additional cooling or anti-wear properties.

I have no hard evidence either, but since oil flow is an important part of
cooling an air-cooled engine, I have to believe that having 50% more oil in
the engine is going to improve cooling performance. It also follows that
having 50% more "clean" oil flushing through the engine should keep
everything internal just that much shinier?

> This is no surprise, really, as the O-360 certainly doesn't *need* six
> or eight quarts of oil. I know of one application (the Seminole) in
> which it is certified to run on as little as 2 quarts.

Well, yes and no. While Lycoming SAYS it's okay to run them down to 2
quarts (or even less), it is nevertheless true that engine cooling will be
hurt by low oil quantities. Sometimes less is more; in this case, only
more is more.

As an adjunct to this discussion, you've got to wonder why aircraft engines
are designed so that in the event of a leak you won't know you're out of oil
until the last pint drains out.

The oil gauge on our engines reads pressure -- not oil capacity. As a
result, you can have a major oil leak and you will not know it until those
last few ounces vent overboard -- and THEN your oil pressure gauge drops to
zero. We recently had a local Skyhawk pilot lose an oil line in flight, and
he did not know he was in trouble until his oil pressure gauge finally
dropped to zero -- at which point the crankcase was already empty, and he
was frying his engine. (He made it to an airport, but destroyed the
engine.)

What baffles me is that no one has come up with an oil QUANTITY gauge like I
have in my Mustang. This would have given the aforementioned pilot an extra
five or ten minutes to get that plane down, BEFORE he had ruined a $16K
engine.

Anyone know?

> Lastly, FWIW, my partner's other airplane (a 182) has a M20 installed.
> Yes, its belly is largely free of oil residue, but it still seems to
> acquire a dry, chaulky residue in any case. It looks and feels like
> something you'd find just aft of an exhaust stack, and may very well
> result from the exhaust...

Oh, I'm sure I'll have some exhaust stains to clean -- but at least I
(hopefully) won't have that slimy belly (with dirt and grass embedded in it)
to clean off.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Jay Honeck]

> Condensation and the sludge buildup that
> would result was my main concern since the M20
> is not dis-assembleable for cleaning like the
> Walker/Air Wolf unit. At each annual I soak it in
> AvGas and then blow it out with compressed air.

I can understand condensation, but sludge?

With regular flying, and scheduled oil and filter changes, what is the
source of sludge in an M20? Combustion bi-products?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[John_F]

If you put too much oil in an engine it will heat up the engine more
because the crankshaft hits the extra oil and causes the oil to be
flung around and this also leads to oil foaming.
Extra heat is generated by flinging the oil around and the bearings
don't get enough oil since the pump does not pump foam well.

A oil quality gauge would be nice but it would add weight and cost. A
simple float switch set at 4 quarts would be nice and should not cost
much?

The old radial's used to have oil tanks that held 5 or 10 GALLONS.

If you really want to know how much water is returned to your engine
by the M20 route the oil return to a quart catch bucket for a few
hours. Then look at the contents of the bucket. One good test is
worth a thousand expert opinions!

I have found over the years that my O320 likes to run at 7 quarts. If
you fill to the max 8 quarts it uses that 8th quart in about 2 hours.
I did discover an interesting effect last month. I normally use a
quart in 4 to 5 hours. By flying at 8000 to 14000 feet for 41 hours
on a trip I only used 2 quarts in 41 hours. Since I was running wide
open throttle I had no engine manifold vacuum most of the time. It
would appear to me that the extra oil usage at part throttle was
caused by the oil being sucked down the intake valve guides.
Someone more knowledgeable may comment on this.

On Sun, 15 Aug 2004 02:44:50 GMT, "Jay Honeck"
> wrote:

>> Air/Oil Separators do seem to perform their intended function with a
>> minimum of problems (when installed correctly, anyway), but my mechanic
>> recommended I NOT install one because they return moisture to the case
>> that would normally be vented overboard with the oil vapor. The
>> long-term effect is reportedly the same as if you were to run the engine
>> for short periods without attaining the operating temperature required
>> to boil off the water -- namely, corrosion.
>
>Thanks for the comments, Doug. I had not heard this, and my mechanic did not
>mention it, but I suppose it makes some sense.
>
>On the other hand, since I fly every few days, I find it hard to imagine
>that moisture could build up (or even survive) a flight with CHTs in the 350
>degree range, and EGTs in the 1500 degree range!
>
>> There is also something to be said, IMHO, for adding oil between oil
>> changes. Oil breaks down over time, and throwing in a quart every 5-10
>> hours replenishes the anti-wear/anti-corrosion additives as well as
>> increases the oil's natural ability to hold contaminants in suspension.
>
>Well, I change my oil around 25 hours minimum, 50 hours maximum. Hopefully
>the billion-dollar-a-quart semi-synthetic Aeroshell oil holds together at
>least THAT long before breaking down?
>
>> Also, I have found no hard evidence that keeping the oil topped vs. 1 or
>> 2 quarts down provides any additional cooling or anti-wear properties.
>
>I have no hard evidence either, but since oil flow is an important part of
>cooling an air-cooled engine, I have to believe that having 50% more oil in
>the engine is going to improve cooling performance. It also follows that
>having 50% more "clean" oil flushing through the engine should keep
>everything internal just that much shinier?
>
>> This is no surprise, really, as the O-360 certainly doesn't *need* six
>> or eight quarts of oil. I know of one application (the Seminole) in
>> which it is certified to run on as little as 2 quarts.
>
>Well, yes and no. While Lycoming SAYS it's okay to run them down to 2
>quarts (or even less), it is nevertheless true that engine cooling will be
>hurt by low oil quantities. Sometimes less is more; in this case, only
>more is more.
>
>As an adjunct to this discussion, you've got to wonder why aircraft engines
>are designed so that in the event of a leak you won't know you're out of oil
>until the last pint drains out.
>
>The oil gauge on our engines reads pressure -- not oil capacity. As a
>result, you can have a major oil leak and you will not know it until those
>last few ounces vent overboard -- and THEN your oil pressure gauge drops to
>zero. We recently had a local Skyhawk pilot lose an oil line in flight, and
>he did not know he was in trouble until his oil pressure gauge finally
>dropped to zero -- at which point the crankcase was already empty, and he
>was frying his engine. (He made it to an airport, but destroyed the
>engine.)
>
>What baffles me is that no one has come up with an oil QUANTITY gauge like I
>have in my Mustang. This would have given the aforementioned pilot an extra
>five or ten minutes to get that plane down, BEFORE he had ruined a $16K
>engine.
>
>Anyone know?
>
>> Lastly, FWIW, my partner's other airplane (a 182) has a M20 installed.
>> Yes, its belly is largely free of oil residue, but it still seems to
>> acquire a dry, chaulky residue in any case. It looks and feels like
>> something you'd find just aft of an exhaust stack, and may very well
>> result from the exhaust...
>
>Oh, I'm sure I'll have some exhaust stains to clean -- but at least I
>(hopefully) won't have that slimy belly (with dirt and grass embedded in it)
>to clean off.

[Roger Halstead]

On Sun, 15 Aug 2004 02:44:50 GMT, "Jay Honeck"
> wrote:

>> Air/Oil Separators do seem to perform their intended function with a
>> minimum of problems (when installed correctly, anyway), but my mechanic
>> recommended I NOT install one because they return moisture to the case
>> that would normally be vented overboard with the oil vapor. The

I think part of this is "old wives tales" as the ABS mechanic
recomended it, my mechanic did, and there are quite a few in service
around the airport.

>> long-term effect is reportedly the same as if you were to run the engine
>> for short periods without attaining the operating temperature required
>> to boil off the water -- namely, corrosion.

At the end of 20 hours my oild is still clean. Not haveing a filter I
change at 25 hours. In a thousand hours of operation I've only added
oil twice. Normally it is down less than a pint at 25 hours.

>
>Thanks for the comments, Doug. I had not heard this, and my mechanic did not
>mention it, but I suppose it makes some sense.
>
>On the other hand, since I fly every few days, I find it hard to imagine
>that moisture could build up (or even survive) a flight with CHTs in the 350
>degree range, and EGTs in the 1500 degree range!

I've had no moisture problem with mine and the air/oild seperator was
put on long before I purchased the plane.

I use straight aeroshel 100 50 weight in summer and 30 in winter.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com
>
>> There is also something to be said, IMHO, for adding oil between oil
>> changes. Oil breaks down over time, and throwing in a quart every 5-10
>> hours replenishes the anti-wear/anti-corrosion additives as well as
>> increases the oil's natural ability to hold contaminants in suspension.
>
>Well, I change my oil around 25 hours minimum, 50 hours maximum. Hopefully
>the billion-dollar-a-quart semi-synthetic Aeroshell oil holds together at
>least THAT long before breaking down?
>
>> Also, I have found no hard evidence that keeping the oil topped vs. 1 or
>> 2 quarts down provides any additional cooling or anti-wear properties.
>
>I have no hard evidence either, but since oil flow is an important part of
>cooling an air-cooled engine, I have to believe that having 50% more oil in
>the engine is going to improve cooling performance. It also follows that
>having 50% more "clean" oil flushing through the engine should keep
>everything internal just that much shinier?
>
>> This is no surprise, really, as the O-360 certainly doesn't *need* six
>> or eight quarts of oil. I know of one application (the Seminole) in
>> which it is certified to run on as little as 2 quarts.
>
>Well, yes and no. While Lycoming SAYS it's okay to run them down to 2
>quarts (or even less), it is nevertheless true that engine cooling will be
>hurt by low oil quantities. Sometimes less is more; in this case, only
>more is more.
>
>As an adjunct to this discussion, you've got to wonder why aircraft engines
>are designed so that in the event of a leak you won't know you're out of oil
>until the last pint drains out.
>
>The oil gauge on our engines reads pressure -- not oil capacity. As a
>result, you can have a major oil leak and you will not know it until those
>last few ounces vent overboard -- and THEN your oil pressure gauge drops to
>zero. We recently had a local Skyhawk pilot lose an oil line in flight, and
>he did not know he was in trouble until his oil pressure gauge finally
>dropped to zero -- at which point the crankcase was already empty, and he
>was frying his engine. (He made it to an airport, but destroyed the
>engine.)
>
>What baffles me is that no one has come up with an oil QUANTITY gauge like I
>have in my Mustang. This would have given the aforementioned pilot an extra
>five or ten minutes to get that plane down, BEFORE he had ruined a $16K
>engine.
>
>Anyone know?
>
>> Lastly, FWIW, my partner's other airplane (a 182) has a M20 installed.
>> Yes, its belly is largely free of oil residue, but it still seems to
>> acquire a dry, chaulky residue in any case. It looks and feels like
>> something you'd find just aft of an exhaust stack, and may very well
>> result from the exhaust...
>
>Oh, I'm sure I'll have some exhaust stains to clean -- but at least I
>(hopefully) won't have that slimy belly (with dirt and grass embedded in it)
>to clean off.

[GaryP]

"Jay Honeck" > wrote in message news:<OaATc.292632$JR4.125853@attbi_s54>...

> I can understand condensation, but sludge?
>
> With regular flying, and scheduled oil and filter changes, what is the
> source of sludge in an M20? Combustion bi-products?

Well they say that cars driven a short distance suffer from sludge
buildup
when the acidic moisture, created as a combustion by-product, remains
in the oil. I believe the same is true in an aircraft engine. Any
place
where entrapped moisture routinely remains in contact with oil will
form
sludge. Look at the vent tube on an airplane with considerable time
on
the engine. Some have sludge build up because they cool the crankcase
vented gases low enough for the moisture to condense out and remain
on the inside walls along with a film of expelled engine oil.
Depending on
where an air/oil seperator is located it too can run cold enough to
become a collector of moisture and therefore suffer from sludge
buildup over time.

My M-20 is located high enough and out of the engine cooling airstream
to
get and stay relatively hot. Since I can't visually inspect my M-20 I
take the proactive measure of cleaning it out each year.
In fact if my memory serves me correctly I believe the instructions
for
continued airworthiness on the M-20 STC says to clean it periodically.

GaryP

[Mike Rapoport]

More oil does not improve cooling. If you think about it, it makes sense.
Where would the additoinal heat go? Same oil cooler, same cooling fins,
same baffles producing the same airflow. The oil will actually be hotter
since the crank is going to contact the oil in the sump with 50% more oil.
Thats why the top 4 qts of oil is leaving through the breather in the first
place.

The oil will be somewhat cleaner since the same amount of contaminates are
dilluted by more oil. As a practical matter, you would probably be better
off with a finer oil filter than more oil. There is an article on oil
filters in Aviation Consumer this month that is worth reading.

Mike
MU-2
Helio Courier (arriving today!)


"Jay Honeck" > wrote in message
news:C6ATc.312310$XM6.196374@attbi_s53...
> > Air/Oil Separators do seem to perform their intended function with a
> > minimum of problems (when installed correctly, anyway), but my mechanic
> > recommended I NOT install one because they return moisture to the case
> > that would normally be vented overboard with the oil vapor. The
> > long-term effect is reportedly the same as if you were to run the engine
> > for short periods without attaining the operating temperature required
> > to boil off the water -- namely, corrosion.
>
> Thanks for the comments, Doug. I had not heard this, and my mechanic did
not
> mention it, but I suppose it makes some sense.
>
> On the other hand, since I fly every few days, I find it hard to imagine
> that moisture could build up (or even survive) a flight with CHTs in the
350
> degree range, and EGTs in the 1500 degree range!
>
> > There is also something to be said, IMHO, for adding oil between oil
> > changes. Oil breaks down over time, and throwing in a quart every 5-10
> > hours replenishes the anti-wear/anti-corrosion additives as well as
> > increases the oil's natural ability to hold contaminants in suspension.
>
> Well, I change my oil around 25 hours minimum, 50 hours maximum.
Hopefully
> the billion-dollar-a-quart semi-synthetic Aeroshell oil holds together at
> least THAT long before breaking down?
>
> > Also, I have found no hard evidence that keeping the oil topped vs. 1 or
> > 2 quarts down provides any additional cooling or anti-wear properties.
>
> I have no hard evidence either, but since oil flow is an important part of
> cooling an air-cooled engine, I have to believe that having 50% more oil
in
> the engine is going to improve cooling performance. It also follows that
> having 50% more "clean" oil flushing through the engine should keep
> everything internal just that much shinier?
>
> > This is no surprise, really, as the O-360 certainly doesn't *need* six
> > or eight quarts of oil. I know of one application (the Seminole) in
> > which it is certified to run on as little as 2 quarts.
>
> Well, yes and no. While Lycoming SAYS it's okay to run them down to 2
> quarts (or even less), it is nevertheless true that engine cooling will be
> hurt by low oil quantities. Sometimes less is more; in this case, only
> more is more.
>
> As an adjunct to this discussion, you've got to wonder why aircraft
engines
> are designed so that in the event of a leak you won't know you're out of
oil
> until the last pint drains out.
>
> The oil gauge on our engines reads pressure -- not oil capacity. As a
> result, you can have a major oil leak and you will not know it until those
> last few ounces vent overboard -- and THEN your oil pressure gauge drops
to
> zero. We recently had a local Skyhawk pilot lose an oil line in flight,
and
> he did not know he was in trouble until his oil pressure gauge finally
> dropped to zero -- at which point the crankcase was already empty, and he
> was frying his engine. (He made it to an airport, but destroyed the
> engine.)
>
> What baffles me is that no one has come up with an oil QUANTITY gauge like
I
> have in my Mustang. This would have given the aforementioned pilot an
extra
> five or ten minutes to get that plane down, BEFORE he had ruined a $16K
> engine.
>
> Anyone know?
>
> > Lastly, FWIW, my partner's other airplane (a 182) has a M20 installed.
> > Yes, its belly is largely free of oil residue, but it still seems to
> > acquire a dry, chaulky residue in any case. It looks and feels like
> > something you'd find just aft of an exhaust stack, and may very well
> > result from the exhaust...
>
> Oh, I'm sure I'll have some exhaust stains to clean -- but at least I
> (hopefully) won't have that slimy belly (with dirt and grass embedded in
it)
> to clean off.
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
>

[Dan Luke]

"Mike Rapoport" wrote:
> More oil does not improve cooling. If you think about it, it
> makes sense. Where would the additoinal heat go? Same
> oil cooler, same cooling fins, same baffles producing the same
> airflow. The oil will actually be hotter...

....so the delta T of the oil cooler-to-air will be greater and the rate
of heat transfer will will be increased, no? Thus more heat will be
removed from the engine.

--
Dan
C172RG at BFM

[Kyle Boatright]

"Dan Luke" > wrote in message
...
>
> "Mike Rapoport" wrote:
> > More oil does not improve cooling. If you think about it, it
> > makes sense. Where would the additoinal heat go? Same
> > oil cooler, same cooling fins, same baffles producing the same
> > airflow. The oil will actually be hotter...
>
> ...so the delta T of the oil cooler-to-air will be greater and the rate
> of heat transfer will will be increased, no? Thus more heat will be
> removed from the engine.
>
> --
> Dan
> C172RG at BFM

I'll add a third opinion: The volume of oil doesn't drive oil temperatures
other than by providing a few more pounds of thermal mass which slightly
reduce the slope of engine temp trend lines. I.E. the engine will warm up
slightly slower and will cool off slightly slower. Once you get to steady
state operations (stabilized temps in cruise flight), you're down to the
fact that the engine transmits X BTU's to the oil, and the oil cooler
rejects Y BTU's. In steady state operations, X and Y are the same...

[Matt Whiting]

Kyle Boatright wrote:
> "Dan Luke" > wrote in message
> ...
>
>>"Mike Rapoport" wrote:
>>
>>>More oil does not improve cooling. If you think about it, it
>>>makes sense. Where would the additoinal heat go? Same
>>>oil cooler, same cooling fins, same baffles producing the same
>>>airflow. The oil will actually be hotter...
>>
>>...so the delta T of the oil cooler-to-air will be greater and the rate
>>of heat transfer will will be increased, no? Thus more heat will be
>>removed from the engine.
>>
>>--
>>Dan
>>C172RG at BFM
>
>
> I'll add a third opinion: The volume of oil doesn't drive oil temperatures
> other than by providing a few more pounds of thermal mass which slightly
> reduce the slope of engine temp trend lines. I.E. the engine will warm up
> slightly slower and will cool off slightly slower. Once you get to steady
> state operations (stabilized temps in cruise flight), you're down to the
> fact that the engine transmits X BTU's to the oil, and the oil cooler
> rejects Y BTU's. In steady state operations, X and Y are the same...
>
>

Except that the oil cooler isn't the only source of heat loss. Heat
from the oil is lost through the cases as well and more oil, to a point,
will reject more heat. The point is, as mentioned earlier, the point
where the oil starts to contact the crank. However, this shouldn't
happen unless you overfill the sump. The manufacturer's fill limit
should avoid windage problems with the crank.


Matt

[Mike Rapoport]

But you are putting more heat in because of having the crank contact the oil
more of the time. The temp will be higher.

Mike
MU-2

"Dan Luke" > wrote in message
...
>
> "Mike Rapoport" wrote:
> > More oil does not improve cooling. If you think about it, it
> > makes sense. Where would the additoinal heat go? Same
> > oil cooler, same cooling fins, same baffles producing the same
> > airflow. The oil will actually be hotter...
>
> ...so the delta T of the oil cooler-to-air will be greater and the rate
> of heat transfer will will be increased, no? Thus more heat will be
> removed from the engine.
>
> --
> Dan
> C172RG at BFM
>
>

[Mike Rapoport]

The case has no more area and no more airflow across its surface with more
oil in the sump.

Mike
MU-2


"Matt Whiting" > wrote in message
...
> Kyle Boatright wrote:
> > "Dan Luke" > wrote in message
> > ...
> >
> >>"Mike Rapoport" wrote:
> >>
> >>>More oil does not improve cooling. If you think about it, it
> >>>makes sense. Where would the additoinal heat go? Same
> >>>oil cooler, same cooling fins, same baffles producing the same
> >>>airflow. The oil will actually be hotter...
> >>
> >>...so the delta T of the oil cooler-to-air will be greater and the rate
> >>of heat transfer will will be increased, no? Thus more heat will be
> >>removed from the engine.
> >>
> >>--
> >>Dan
> >>C172RG at BFM
> >
> >
> > I'll add a third opinion: The volume of oil doesn't drive oil
temperatures
> > other than by providing a few more pounds of thermal mass which slightly
> > reduce the slope of engine temp trend lines. I.E. the engine will warm
up
> > slightly slower and will cool off slightly slower. Once you get to
steady
> > state operations (stabilized temps in cruise flight), you're down to the
> > fact that the engine transmits X BTU's to the oil, and the oil cooler
> > rejects Y BTU's. In steady state operations, X and Y are the same...
> >
> >
>
> Except that the oil cooler isn't the only source of heat loss. Heat
> from the oil is lost through the cases as well and more oil, to a point,
> will reject more heat. The point is, as mentioned earlier, the point
> where the oil starts to contact the crank. However, this shouldn't
> happen unless you overfill the sump. The manufacturer's fill limit
> should avoid windage problems with the crank.
>
>
> Matt
>

[[email protected]]

On Sun, 15 Aug 2004 06:17:09 GMT, (John_F) wrote:

>If you put too much oil in an engine it will heat up the engine more
>because the crankshaft hits the extra oil and causes the oil to be
>flung around and this also leads to oil foaming.
>Extra heat is generated by flinging the oil around and the bearings
>don't get enough oil since the pump does not pump foam well.

Any aircraft engine crankcase I've been inside of has relatively small
slots below the crank where the case halves meet effectively isolating
the sump from the crank in regard to "windage".

TC

snip

[Jay Honeck]

> Any aircraft engine crankcase I've been inside of has relatively small
> slots below the crank where the case halves meet effectively isolating
> the sump from the crank in regard to "windage".

Ah! The man who truly *knows* weighs in!

:-)

So how 'bout it, TC -- is the M20 a good thing, a bad thing, or 'bout the
same thing with regards to my O-540?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Matt Whiting]

Mike Rapoport wrote:

> But you are putting more heat in because of having the crank contact the oil
> more of the time. The temp will be higher.

Is this true in Lycs and Contis? I don't know about the airplane
engines, but car engines have the upper fill limit established to
prevent this. Having the crank contact the oil will froth it pretty
quickly and the oil pump can't pump aerated oil very well. This is why
the dipstick always has a warning not to overfill. I'd be surprised if
airplane engines permitted a fill to the point of crank contact. This
is generally only done intentionally on splash lubricated engines such
as those found in cheap lawnmowers.


Matt

[Matt Whiting]

Mike Rapoport wrote:

> The case has no more area and no more airflow across its surface with more
> oil in the sump.

No kidding, but it does have more oil contact area and thus the oil can
transfer more heat to the case.


Matt

[Mike Rapoport]

The oil level is about 1" higher and the case is highly conductive.

Mike
MU-2


"Matt Whiting" > wrote in message
...
> Mike Rapoport wrote:
>
> > The case has no more area and no more airflow across its surface with
more
> > oil in the sump.
>
> No kidding, but it does have more oil contact area and thus the oil can
> transfer more heat to the case.
>
>
> Matt
>

[Mike Rapoport]

The crank in not in contact all the time but the oil is sloshing around as
the airplane moves. When the level gets down to where it isn't contacting
the crank, the oil stops being blown out the breather (at least in
meaningful quantities.)

Mike
MU-2

"Matt Whiting" > wrote in message
...
> Mike Rapoport wrote:
>
> > But you are putting more heat in because of having the crank contact the
oil
> > more of the time. The temp will be higher.
>
> Is this true in Lycs and Contis? I don't know about the airplane
> engines, but car engines have the upper fill limit established to
> prevent this. Having the crank contact the oil will froth it pretty
> quickly and the oil pump can't pump aerated oil very well. This is why
> the dipstick always has a warning not to overfill. I'd be surprised if
> airplane engines permitted a fill to the point of crank contact. This
> is generally only done intentionally on splash lubricated engines such
> as those found in cheap lawnmowers.
>
>
> Matt
>

[[email protected]]

On Mon, 16 Aug 2004 02:35:58 GMT, "Jay Honeck"
> wrote:

>> Any aircraft engine crankcase I've been inside of has relatively small
>> slots below the crank where the case halves meet effectively isolating
>> the sump from the crank in regard to "windage".
>
>Ah! The man who truly *knows* weighs in!
>
>:-)
>
>So how 'bout it, TC -- is the M20 a good thing, a bad thing, or 'bout the
>same thing with regards to my O-540?

I've read mixed reports about the M20, unfortunately have no personal
experience. Have heard people swear by them, have heard people swear
at them.

Have taken care of several Bo's with the original Walker (?) air/oil
sep. They were for the most part equipped with wet vac pumps as well.
In those cases, there was what I would consider to be an acceptable
accumulation of oil on the belly.

I can't really speak with any authority on the whole "putting crud
back in the crankcase" deal, but I can add that every 325-350 hp
Navajo breathes through a factory-installed air/oil sep. My guess
would be that these engines tend to be heavy-breathers. When they get
up there in hours, the oil stripe on the bottom cowl gets heavier, in
spite of the air/oil sep.

Was never of the mind to bypass one to see how much difference they
make. Cleaned the inside of them rather infrequently, usually at
mid-time (900-1000 hrs) and at TBO.

We ran the Navajo's at 11 qts after an oil change, usually keeping
them between 10 and 11 in service (dump in a qt when it get down
around 10). Actually, never really thought about the air/oil sep being
a factor in determining that level.

Only ever had one come up shy on TBO-catastrophic turbo failure w/oil
contamination. Don't think I coulda blamed that one on crud from the
ari/oil sep...

TC

[Matt Whiting]

Mike Rapoport wrote:

> The oil level is about 1" higher and the case is highly conductive.

So, 1" times the circumference of the case is a fair bit of area and
with a highly thermally conductive Al case, that will reject additional
heat to be sure.


Matt

[Bill Hale]

"Mike Rapoport" > wrote in message >...
> More oil does not improve cooling. If you think about it, it makes sense.
> Where would the additoinal heat go? Same oil cooler, same cooling fins,
> same baffles producing the same airflow. The oil will actually be hotter
> since the crank is going to contact the oil in the sump with 50% more oil.
> Thats why the top 4 qts of oil is leaving through the breather in the first
> place.
>
> The oil will be somewhat cleaner since the same amount of contaminates are
> dilluted by more oil. As a practical matter, you would probably be better
> off with a finer oil filter than more oil. There is an article on oil
> filters in Aviation Consumer this month that is worth reading.
>
> Mike
> MU-2
> Helio Courier (arriving today!)


I'm convinced Mike is right about this. Fits in the same category as the
argument that
auto coolant works more poorly without the thermostat 'cuz it goes thru
the radiator "too fast" and doesn't cool properly.

Another triumph of math & science.

Bill Hale

[Bill Hale]

So let me try a theory here.

The lack of positive crankcase ventilation for these
engines is really a bad feature.

A friend measured the PH of the condensate water on the oil dipstick
of an IO-520. PH was 2: Like nitric acid. Having that in
your crankcase is bad.

So why shouldn't we provide PCV by dumping the output of
the wet vacuum pump directly into the crankcase? On the
IO engines, I'd run it into the timing plug in the front.

Then I'd have the air-oil separator on the crankcase breather.

That would give several CFM of air douching the crankcase.

Now the problem is: How much moisture would be condensed out
of the breather air? A gallon/hour? An ounce/hour?

I've wondered if the Airwolf/Walker separator could be modified
so that the oil drain had about a 3/4" standpipe in it with a second
drain added for water that was flush with the bottom of the device.
Then the water could be drained during preflight. The oil would
decant back into the crankcase.

I know there are EPA considerations on this.

Just a thought. I think less corrosion would lengthen the
cylinder life. Bill Hale

[Dan Luke]

"Mike Rapoport" wrote:
> But you are putting more heat in because of having the crank
> contact the oil more of the time. The temp will be higher.

Yes. Therefore the oil cooler will be hotter, therefore the delta T vs.
the ambient air will be higher, therefore the rate of heat transfer will
be increased, therefore more heat will be removed, therefore cooling is
improved by carrying more oil.
--
Dan
C172RG at BFM

[Mike Rapoport]

Right, cooliong is improved (as measured by BTUs extracted) but the oil is
still hotter.

Mike
MU-2


"Dan Luke" > wrote in message
...
>
> "Mike Rapoport" wrote:
> > But you are putting more heat in because of having the crank
> > contact the oil more of the time. The temp will be higher.
>
> Yes. Therefore the oil cooler will be hotter, therefore the delta T vs.
> the ambient air will be higher, therefore the rate of heat transfer will
> be increased, therefore more heat will be removed, therefore cooling is
> improved by carrying more oil.
> --
> Dan
> C172RG at BFM
>
>

[Mike Rapoport]

You are not getting it. How much hotter do you think the case is 1" above
the oil level? About the same. The important part of this is that you are
adding more heat by raising the oil level because the crank is thrashing
about in the oil. That is why the oil is vented overboard when you fill
the case. Try different oil levels in your airplane and see for yourself.
You probably won't be able to measure the difference unless you have a
digital oil temp guage. It also take power to thrash that crank through the
oil, power that would go into turning your prop otherwise. This whole issue
is one reason why race cars use dry sump lubrication systems.

Mike
MU-2


"Matt Whiting" > wrote in message
...
> Mike Rapoport wrote:
>
> > The oil level is about 1" higher and the case is highly conductive.
>
> So, 1" times the circumference of the case is a fair bit of area and
> with a highly thermally conductive Al case, that will reject additional
> heat to be sure.
>
>
> Matt
>

[Matt Whiting]

Mike Rapoport wrote:

> You are not getting it. How much hotter do you think the case is 1" above
> the oil level? About the same. The important part of this is that you are
> adding more heat by raising the oil level because the crank is thrashing
> about in the oil. That is why the oil is vented overboard when you fill
> the case. Try different oil levels in your airplane and see for yourself.
> You probably won't be able to measure the difference unless you have a
> digital oil temp guage. It also take power to thrash that crank through the
> oil, power that would go into turning your prop otherwise. This whole issue
> is one reason why race cars use dry sump lubrication systems.

No, you're not getting it. If the oil is hotter than the case, then it
will lose heat through the case. If it is losing heat through the case,
then being in contact with more case area will result in more heat transfer.

I honestly don't know if the oil contacts the crank in a typical Lyc or
Conti. It may, it may not. I'd be very surprised if it does, because
most engines with pressure lubrication systems tend to fail very quickly
when any substantial amount of oil in the sump contacts the crank. That
is why overfilling a crank is so strongly warned against by almost all
engine makers.


Matt

[Mike Rapoport]

Don't take my word for it! Try flying your airplane full and then at
whatever the oil level stabilizes at. If the oil didn't contact the crank,
then it wouldn't be expelled out the breather (on a healthy engine). The
oil may not contact the crank in level, smooth, unaccelerated flight but it
does under acceleration, climb and descent.

Mike
MU-2


"Matt Whiting" > wrote in message
...
> Mike Rapoport wrote:
>
> > You are not getting it. How much hotter do you think the case is 1"
above
> > the oil level? About the same. The important part of this is that you
are
> > adding more heat by raising the oil level because the crank is thrashing
> > about in the oil. That is why the oil is vented overboard when you
fill
> > the case. Try different oil levels in your airplane and see for
yourself.
> > You probably won't be able to measure the difference unless you have a
> > digital oil temp guage. It also take power to thrash that crank through
the
> > oil, power that would go into turning your prop otherwise. This whole
issue
> > is one reason why race cars use dry sump lubrication systems.
>
> No, you're not getting it. If the oil is hotter than the case, then it
> will lose heat through the case. If it is losing heat through the case,
> then being in contact with more case area will result in more heat
transfer.
>
> I honestly don't know if the oil contacts the crank in a typical Lyc or
> Conti. It may, it may not. I'd be very surprised if it does, because
> most engines with pressure lubrication systems tend to fail very quickly
> when any substantial amount of oil in the sump contacts the crank. That
> is why overfilling a crank is so strongly warned against by almost all
> engine makers.
>
>
> Matt
>

[Jay Honeck]

Well, I've now flown the plane on four cross-country flights with the new
M20 installed, for a total of 5.1 hours, since Sunday.

The results: Oil level is unchanged and stable at a hair below 12 quarts,
while oil temperatures (according to the JPI engine analyzer) are
stabilizing in the 190 degree range -- unchanged from before.

Intangibles: It may be my imagination, but the prop seems to be cycling
just a tad slower than before during our pre-flight checks. I could be
crazy, though . (Mary didn't sense it, but I find that I am much more "in
tune" with mechanical things than she is...)

Could more oil in the system cause such a thing? It seems illogical, from
what I know about the variable-pitch prop system.

I just paid my son to clean the belly "one last time" today -- I hope from
now on it's just dust and dirt, not oil!

> I can't really speak with any authority on the whole "putting crud
> back in the crankcase" deal, but I can add that every 325-350 hp
> Navajo breathes through a factory-installed air/oil sep.

The Navajo runs a higher horsepower version of my engine, right TC?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[dave]

I just checked the airwolf.com site. Let me say that I know nothing
about separators. Airwolf's website made me curious. Airwolf shows a
cutaway of the m20 to prove that it's an inferior product but not a
cutaway of their own product. They also claim that the oil from
competitor's products does not flow back to the engine until after the
engine is shutdown. Does this mean that the separator in Jay's plane is
holding four quarts of oil? Maybe the beauty of the M20 is it's
simplicity.
Dave
68 7ECA

Jay Honeck wrote:
> Atlas just got his oil/air separator installed today. (For those who may
> not know, Atlas is our '74 Cherokee Pathfinder, so-named because he can lift
> literally anything we can fit inside!)
>
> We picked this new accessory up at OSH '04, after much debate. (It's a
> helluva lot of money for what looks like a welded tin can.) The clincher
> (besides the nice clean belly) is that I'll be able to run a full 12 quarts
> of oil in our Lycoming O-540, rather than the 8.5 quarts we could hold
> before. (Atlas would puke out the four extra quarts, if added.)
>
> It seems logical to assume that more oil in the engine equals cleaner oil to
> all engine parts, at all times. This seems like a very good thing, indeed.
>
> Anyone else got one of these things? Are there any "gotchas" to watch out
> for, or are they as bullet-proof as they seem?
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination
>
>

[Kai Glaesner]

All,

> I just checked the airwolf.com site. [...]

I did, too. It's slightly OT, but has anyone tried their remote oil-filter?
The idea looks promising (and our hangar floor would benefit from
"hassel-free" oil-filter change ;-)

Regards

Kai

[Paul Sengupta]

"Jay Honeck" > wrote in message
news:1tyUc.34503$TI1.2330@attbi_s52...
> Intangibles: It may be my imagination, but the prop seems to be cycling
> just a tad slower than before during our pre-flight checks. I could be
> crazy, though . (Mary didn't sense it, but I find that I am much more "in
> tune" with mechanical things than she is...)
>
> Could more oil in the system cause such a thing? It seems illogical, from
> what I know about the variable-pitch prop system.

Could it be that the oil is cooler (more to heat up) at the run-up
stage?

Paul

[Bushy]

> I did, too. It's slightly OT, but has anyone tried their remote
oil-filter?

Not theirs, but many years ago I raced a VW kit car and the remote oil
filter I added allowed more oil to be in the system and ceratinly allowed me
to get high power for longer before the oil temperature would climb.

Maybe having it in a remote location with some air flow allowed a better
cooling, and maybe the increased oil capacity helped by allowing for a
slower overall climb in temperature. It certainly helped to maintain a more
stable temperature with the short periods of full power that I subjected it
to in motorkana events.

An aircraft is normally only subjected to full power for take off and go
round, and many manufacturers quote full power rating for one minute or
similar times.

Hope this helps,
Peter

[[email protected]]

On Wed, 18 Aug 2004 01:41:17 GMT, "Jay Honeck"
> wrote:

Below

>Well, I've now flown the plane on four cross-country flights with the new
>M20 installed, for a total of 5.1 hours, since Sunday.
>
>The results: Oil level is unchanged and stable at a hair below 12 quarts,
>while oil temperatures (according to the JPI engine analyzer) are
>stabilizing in the 190 degree range -- unchanged from before.
>
>Intangibles: It may be my imagination, but the prop seems to be cycling
>just a tad slower than before during our pre-flight checks. I could be
>crazy, though . (Mary didn't sense it, but I find that I am much more "in
>tune" with mechanical things than she is...)
>
>Could more oil in the system cause such a thing? It seems illogical, from
>what I know about the variable-pitch prop system.
>
>I just paid my son to clean the belly "one last time" today -- I hope from
>now on it's just dust and dirt, not oil!
>
>> I can't really speak with any authority on the whole "putting crud
>> back in the crankcase" deal, but I can add that every 325-350 hp
>> Navajo breathes through a factory-installed air/oil sep.
>
>The Navajo runs a higher horsepower version of my engine, right TC?

Not exactly. The cylinder design is canted-valve, with the intake
coming in the bottom side and the exhaust exiting on top-opposed to to
your engine with parallel valves, and the intake and exhaust pipes on
the bottom. It also has a slightly different induction housing with a
larger common plenum with internal extensions to effectively lengthen
the intake pipes.

I probably should have made it clear that the air/oil sep is a Piper
factory installation, not Lycoming.

TC

[Mike Rapoport]

The plane I just bought has an Airwolf adapter according to the paperwork
but I haven't even seen it yet. I'll let you know.

Mike
MU-2
Helio Courier


"Kai Glaesner" > wrote in message
...
> All,
>
> > I just checked the airwolf.com site. [...]
>
> I did, too. It's slightly OT, but has anyone tried their remote
oil-filter?
> The idea looks promising (and our hangar floor would benefit from
> "hassel-free" oil-filter change ;-)
>
> Regards
>
> Kai
>
>

[Jay Honeck]

> I did, too. It's slightly OT, but has anyone tried their remote
oil-filter?
> The idea looks promising (and our hangar floor would benefit from
> "hassel-free" oil-filter change ;-)

We installed one on our O-540 during the rebuild two years ago, and love it.
It makes changing the oil MUCH easier, especially on an O-540, where the
filter was mounted horizontally on the top/back of the engine. When you
unscrewed it, the filter would literally back up into the firewall (which
was dented from all the years of doing this), and you could just barely get
it out.

Meanwhile, of course, you were dumping the entire quart of oil all over the
engine...

Now, it's ALMOST a clean job. I still seem to manage to get oil everywhere,
but that's probably just me!

;-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Jay Honeck]

> I probably should have made it clear that the air/oil sep is a Piper
> factory installation, not Lycoming.

That's interesting. Who manufactured it for Piper?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Dave Butler]

Bushy wrote:
>>I did, too. It's slightly OT, but has anyone tried their remote
>
> oil-filter?

If the installation involves running hoses to the remote location, I'd see that
as an unnecesary extra leak risk.

[Jay Honeck]

> If the installation involves running hoses to the remote location, I'd see
that
> as an unnecesary extra leak risk.

I agree, but in our case the convenience out-weighed the risk.

The previous owner admitted that he only changed his oil every 50 or more
hours, simply because of the incredible mess and hassle. We change ours
every 25 or so, for the good of the engine and because it's really easy.

BTW: The hoses Air Wolf supplied are extremely high quality stainless-steel
braided lines. They appear pretty bullet-proof.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[[email protected]]

On Wed, 18 Aug 2004 15:54:40 GMT, "Jay Honeck"
> wrote:

>> I probably should have made it clear that the air/oil sep is a Piper
>> factory installation, not Lycoming.
>
>That's interesting. Who manufactured it for Piper?

No clue. Had a generic Piper part number inked on it.

Looks about like a tuna can with a shallow funnel attached to the
bottom with a drain fitting attached.

Inlet is a piece of tubing scarf-cut and welded on to the side of the
"can" so the airflow would tend to rotate around in the can (I guess).

Outlet straight up out of the center of the flat lid screwed to the
top of the sep. There's a cylindrical (sp?) screen with a flat bottom
welded to the inside of the lid.

Is mounted relatively close to the breather fitting on the accessory
case, I'm guessing the hose connecting the engine to the sep inlet is
less than six inches long.

TC

[Kai Glaesner]

Dave,

> If the installation involves running hoses to the remote location, I'd see
that
> as an unnecesary extra leak risk.

I'm concerned about this, too. In addition I wonder if there is a noticeable
drop in oil pressure due to the extra resistance in the hoses.

Otherwise changing the oil filter in our Club's Warrior and Dakota IS a mess
and I never stay unstained ... ;-)

Regards

Kai

[David Lesher]

I have to wonder about the statements that an oil/air separator will
increase the sludge because H2O will be retained.

I assume there's an atmosphere vent on the separator, no? [Cars no longer
have same; the PCV system ducts the vapor back into the air cleaner
to be burned...]

ISTM that as you reach operating temperature, the water in the oil gets
evaporated out and vented off; separator or not. Is there some reason this
does not happen?

--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

[CriticalMass]

John_F wrote:
>By flying at 8000 to 14000 feet for 41 hours
> on a trip I only used 2 quarts in 41 hours. Since I was running wide
> open throttle I had no engine manifold vacuum most of the time. It
> would appear to me that the extra oil usage at part throttle was
> caused by the oil being sucked down the intake valve guides.
> Someone more knowledgeable may comment on this.

My guess would be that your engine makes only 50% or less, much less at
14,000 feet, percent power, and it won't use much oil at such low power
settings.

[Michael 182]

"Jay Honeck" > wrote in message
news:CyfTc.304529$XM6.124022@attbi_s53...
> Atlas just got his oil/air separator installed today. (For those who may
> not know, Atlas is our '74 Cherokee Pathfinder, so-named because he can
lift
> literally anything we can fit inside!)
>
> We picked this new accessory up at OSH '04, after much debate. (It's a
> helluva lot of money for what looks like a welded tin can.) The clincher
> (besides the nice clean belly) is that I'll be able to run a full 12
quarts
> of oil in our Lycoming O-540, rather than the 8.5 quarts we could hold
> before. (Atlas would puke out the four extra quarts, if added.)
>
> It seems logical to assume that more oil in the engine equals cleaner oil
to
> all engine parts, at all times. This seems like a very good thing,
indeed.
>
> Anyone else got one of these things? Are there any "gotchas" to watch out
> for, or are they as bullet-proof as they seem?
>

I installed one on my TR-182 which had an incredibly messy belly. It did a
great job, almost completely getting rid of the mess.

I have no idea about the volume argument, but empirically it did not happen
on my plane. The TIO-540 has an 8 qt capacity. Anything over 6.5 quarts gets
blown out, before and after the M-20 went in.

Michael

[JJS]

Gene,
Thanks for the education. One old wive's tale put to rest as far
as I'm concerned.
Joe Schneider
Cherokee 8437R

"Gene Kearns" > wrote in message
...
> On Sat, 14 Aug 2004 08:19:12 -0500, "JJS" <jschneider@REMOVE
> SOCKSpldi.net> wrote:
>
> >From what I've read here on Rec. Av. * the downside to these oil
> >separators is that they may also return the moisture, acids, and
other
snip
> M-20 begs to differ....
>
> http://www.m-20turbos.com/separator_facts.htm
>

[Marc J. Zeitlin]

JJS wrote;

> Gene,
> Thanks for the education. One old wive's tale put to rest as far
> as I'm concerned.

The fact that a manufacturer claims something is not necessarily an
indication that it's true. I would think that independent tests would
be the way to figure this out.

--
Marc J. Zeitlin
http://marc.zeitlin.home.comcast.net/
http://www.cozybuilders.org/
Copyright (c) 2004
..

[Jay Honeck]

> I have no idea about the volume argument, but empirically it did not
happen
> on my plane. The TIO-540 has an 8 qt capacity. Anything over 6.5 quarts
gets
> blown out, before and after the M-20 went in.

This doesn't make sense to me.

A) Why would your TIO-540 blow everything except 6.5 quarts, while my O-540
would settle at 8?

B) Why would any oil "blow over" at all with the air/oil separator
installed?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Michael 182]

"Jay Honeck" > wrote in message
news:2IFYc.3300$_g7.2378@attbi_s52...
> > I have no idea about the volume argument, but empirically it did not
> happen
> > on my plane. The TIO-540 has an 8 qt capacity. Anything over 6.5 quarts
> gets
> > blown out, before and after the M-20 went in.
>
> This doesn't make sense to me.
>
> A) Why would your TIO-540 blow everything except 6.5 quarts, while my
O-540
> would settle at 8?

My engine only holds 8. I believe yours holds quite a bit more.


>
> B) Why would any oil "blow over" at all with the air/oil separator
> installed?

I can't explain this one. I know oil/air seperator's clain to stop blow by,
but at least in my plane, the level stays at 6.5. Just empiracal data.



> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
>

[Jay Honeck]

> > A) Why would your TIO-540 blow everything except 6.5 quarts, while my
> O-540
> > would settle at 8?
>
> My engine only holds 8. I believe yours holds quite a bit more.

What??? A turbo-charged O-540 holds only 8 quarts of oil?

I thought a turbo-charged engine ran hotter, and therefore needed more oil
for lubrication and cooling? My normally aspirated, cool-running O-540
holds 13 quarts!

> > B) Why would any oil "blow over" at all with the air/oil separator
> > installed?
>
> I can't explain this one. I know oil/air seperator's clain to stop blow
by,
> but at least in my plane, the level stays at 6.5. Just empiracal data.

What the heck is the point of having an air/oil separator if it's still
blowing the oil overboard?

I'd have the installation checked, cuz something sure sounds amiss...
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Mike Rapoport]

Didn't we go through this already. More sump capacity doesn't provide "more
lubrication and cooling". You noted this yourself when you installed the
separator and the oil temp was unchanged.

Mike
MU-2


"Jay Honeck" > wrote in message
news:QXcZc.80369$9d6.21156@attbi_s54...
> > > A) Why would your TIO-540 blow everything except 6.5 quarts, while my
> > O-540
> > > would settle at 8?
> >
> > My engine only holds 8. I believe yours holds quite a bit more.
>
> What??? A turbo-charged O-540 holds only 8 quarts of oil?
>
> I thought a turbo-charged engine ran hotter, and therefore needed more oil
> for lubrication and cooling? My normally aspirated, cool-running O-540
> holds 13 quarts!
>
> > > B) Why would any oil "blow over" at all with the air/oil separator
> > > installed?
> >
> > I can't explain this one. I know oil/air seperator's clain to stop blow
> by,
> > but at least in my plane, the level stays at 6.5. Just empiracal data.
>
> What the heck is the point of having an air/oil separator if it's still
> blowing the oil overboard?
>
> I'd have the installation checked, cuz something sure sounds amiss...
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
>

[Jay Honeck]

> Didn't we go through this already. More sump capacity doesn't provide
"more
> lubrication and cooling". You noted this yourself when you installed the
> separator and the oil temp was unchanged.

Actually, I read all the posts in that thread, and concluded that no one
could prove anything one way or the other.

As for the oil temperature read-out being unchanged, I guess I wouldn't
expect it to read cooler at the probe, assuming the oil cooler was working
properly to begin with. With more oil, however, the system may be "working
less hard" to achieve that same temperature.

But I quite honestly don't know if that's what's really happening.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Mike Rapoport]

I concluded that you proved it! If the oil is cooler it should read cooler
everywhere. I don't understand what you mean by "the system working less
hard". The pump is working the same and every other part is static. I can
tell you that in a MU-2 there is no mearsurable difference in temp with
differing oil levels. I can tell you that in a Turbo Lance that there is no
measureable difference in temp with different oil levels. I can tell you
that in my GT-1 race car that there is no measureable difference in oil temp
with different oil levels (and we varied them from 5qts to 12qts). The
bottom line is that there is no difference in temp with differing oil levels
as long as they are not so low that the pump pickup sucks air or so high
that the crank makes frequent contact with the oil in the sump.

Mike
MU-2


"Jay Honeck" > wrote in message
news:8MmZc.270376$eM2.58038@attbi_s51...
> > Didn't we go through this already. More sump capacity doesn't provide
> "more
> > lubrication and cooling". You noted this yourself when you installed
the
> > separator and the oil temp was unchanged.
>
> Actually, I read all the posts in that thread, and concluded that no one
> could prove anything one way or the other.
>
> As for the oil temperature read-out being unchanged, I guess I wouldn't
> expect it to read cooler at the probe, assuming the oil cooler was working
> properly to begin with. With more oil, however, the system may be
"working
> less hard" to achieve that same temperature.
>
> But I quite honestly don't know if that's what's really happening.
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
>

[Matt Whiting]

Mike Rapoport wrote:

> Didn't we go through this already. More sump capacity doesn't provide "more
> lubrication and cooling". You noted this yourself when you installed the
> separator and the oil temp was unchanged.

Discussing it doesn't resolve it. I agree it doesn't provide more
lubrication, but I've yet to see any credible evidence of the affect on
cooling. I believe it helps, you don't believe it helps, but I don't
think either of us has any data to prove one way or the other.


Matt

[Mike Rapoport]

I thought Jay's experience of no change in temp was enough data.

Mike
MU-2


"Matt Whiting" > wrote in message
...
> Mike Rapoport wrote:
>
> > Didn't we go through this already. More sump capacity doesn't provide
"more
> > lubrication and cooling". You noted this yourself when you installed
the
> > separator and the oil temp was unchanged.
>
> Discussing it doesn't resolve it. I agree it doesn't provide more
> lubrication, but I've yet to see any credible evidence of the affect on
> cooling. I believe it helps, you don't believe it helps, but I don't
> think either of us has any data to prove one way or the other.
>
>
> Matt
>

[Matt Whiting]

Mike Rapoport wrote:

> I thought Jay's experience of no change in temp was enough data.

Well, one data point is hardly compelling evidence. And the affect
might be too small to measure on the typical aircraft gauge which may
have a resolution of 3-5 degres if you are lucky. Also, you'd have to
carefully control conditions to be sure that the OAT was identical, etc.
For all I know, he may have been flying on two different days with
fairly different flight conditions.


Matt

[Jay Honeck]

> I thought Jay's experience of no change in temp was enough data.

I don't see how you can conclude anything from the fact that the temperature
gauge reads the same.

If the oil cooler is working properly, it should keep the oil at a
steady-state temperature. In order to achieve that steady-state, it my have
to work much harder (I.E.: The thermostat may have to keep more oil flowing
through the cooler in order to maintain that steady temperature.) with less
oil on board to provide cooling.

This seems intuitive, but I honestly don't know enough about thermal
dynamics and engine design to conclusively say anything one way or the
other.

What we're not able to measure is how much "easier" it is for the engine to
remain at the a relatively cool 180 degrees, now that I've got 12 quarts
flowing through it instead of only 8.

I suppose the way to prove (or disprove) this theory would be to push the
engine to the limit, first with 8 and then with 12 quarts of oil on board,
and see if it overheats more quickly with less oil on board.

I suggest we try that with one of *your* engines first...

;-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[John_F]

There are two terms in this temperature equation.

One is steady state thermal transfer rate. If you generate a
quantity of heat say one BTU then it will raise one quart of oil X
degrees F. If you add two times as much heat to the same oil it will
raise the temperature of the quart of oil 2X degrees F.
At any given RPM the oil pump will pump "Y" quarts of oil per minute
whether you have 2 quarts or 10 quarts in the sump since the pump is a
gear positive displacement pump. This means that the oil will carry
of the SAME amount of heat per minute if the temperature delta is the
same. If you want to get rid of more heat then you have to pump the
oil faster or heat the oil hotter to get a larger delta temperature
difference. This is the steady state condition. This is the condition
the engine is in when the temperature gage quits moving up.

The other part of the equation is the transient part that occurs on
warm up of the engine If one BTU will rase one quart of oil X degrees
then it will take ten BTUs to raise ten quarts of oil X degrees. It
might take an extra two or three minutes to raise the extra 8 quarts
of oil to the final steady state temperature. Once this temperature
was reached the extra 8 quarts does nothing for you unless you have a
big leak and start dumping oil overboard in which case it gives you
some more time before the oil all runs out.

If you put too much oil in the engine such that the crank shaft hits
the surface of the oil in the sump then a lot of mechanical energy is
transferred into the oil which heats the oil excessively due to the
excessive splashing.

The end result is the oil and engine temperature will be the same in
less than 30 minutes whether you have 2 quarts or 10 quarts as long as
the crank is not hitting the surface of the oil or you are not sucking
air into the pump due to low oil level at the pump inlet.

On Thu, 02 Sep 2004 01:29:49 GMT, "Jay Honeck"
> wrote:

>> I thought Jay's experience of no change in temp was enough data.
>
>I don't see how you can conclude anything from the fact that the temperature
>gauge reads the same.
>
>If the oil cooler is working properly, it should keep the oil at a
>steady-state temperature. In order to achieve that steady-state, it my have
>to work much harder (I.E.: The thermostat may have to keep more oil flowing
>through the cooler in order to maintain that steady temperature.) with less
>oil on board to provide cooling.
>
>This seems intuitive, but I honestly don't know enough about thermal
>dynamics and engine design to conclusively say anything one way or the
>other.
>
>What we're not able to measure is how much "easier" it is for the engine to
>remain at the a relatively cool 180 degrees, now that I've got 12 quarts
>flowing through it instead of only 8.
>
>I suppose the way to prove (or disprove) this theory would be to push the
>engine to the limit, first with 8 and then with 12 quarts of oil on board,
>and see if it overheats more quickly with less oil on board.
>
>I suggest we try that with one of *your* engines first...
>
>;-)

[Frank Stutzman]

Jay Honeck > wrote:

> I suppose the way to prove (or disprove) this theory would be to push the
> engine to the limit, first with 8 and then with 12 quarts of oil on board,
> and see if it overheats more quickly with less oil on board.

> I suggest we try that with one of *your* engines first...

I think John Deakin of Avwebs Pelican Perch did this but in the opposite
direction...

He had an engine in his plane that was due for an overhaul. I don't
remember the situation, but he was willing to destroy it for the
information. Anyway, it was an Continental IO-550 or a -520 that normally
uses 8 to 10 quarts in the sump. He ran it on 2. He ran it hard. Not
only did the engine not self-destruct, he didn't even see an increase in
oil temperature.

I thought he wrote about this in one of his Pelican Perch articals, but I
can't seem to find it.

--
Frank Stutzman
Bonanza N494B "Hula Girl"
Hood River, OR

[Matt Whiting]

Jay Honeck wrote:


> I suppose the way to prove (or disprove) this theory would be to push the
> engine to the limit, first with 8 and then with 12 quarts of oil on board,
> and see if it overheats more quickly with less oil on board.
>
> I suggest we try that with one of *your* engines first...
>
> ;-)

The only way to control things would be to use an engine on a dyno.
Unfortunately, I don't have a dyno in my garage. :-)


Matt

[Matt Whiting]

John_F wrote:

> There are two terms in this temperature equation.
>
> One is steady state thermal transfer rate. If you generate a
> quantity of heat say one BTU then it will raise one quart of oil X
> degrees F. If you add two times as much heat to the same oil it will
> raise the temperature of the quart of oil 2X degrees F.
> At any given RPM the oil pump will pump "Y" quarts of oil per minute
> whether you have 2 quarts or 10 quarts in the sump since the pump is a
> gear positive displacement pump. This means that the oil will carry
> of the SAME amount of heat per minute if the temperature delta is the
> same. If you want to get rid of more heat then you have to pump the
> oil faster or heat the oil hotter to get a larger delta temperature
> difference. This is the steady state condition. This is the condition
> the engine is in when the temperature gage quits moving up.

Or you start with cooler oil in the sump. This is what, I believe, will
happen when you have more oil in the engine. The oil has a longer
residence time in the sump and contacts more surface area of the sump
through which it may dissipate heat.

Let's run a "thought" experiment at the limits. Let's assume that the
oil level is so low that no oil is ever in the sump. The oil pump pulls
it out just as fast as it comes in, just short of the point of sucking
air. I realize this isn't possible in the real world, but that is why
this is a thought experiment. In this case, the oil will get very hot
as it is constantly being circulated through the heads which are one of
the hottest parts of most engines. The oil has very little opportunity
to reject heat in the coolest part of the engine, the sump. The
equilibrium temperature will be rather high.

Now take the other extreme. The oil sump has infinite capacity so the
oil starts out at the same temperature regardless of how hot the hot
parts of the engine are. The oil will enter the oil pump relatively
cool and pick up heat, but will never again get circulated through the
engine so it has "forever" to dissipate its heat.

A real engine is somewhere in between these to limit cases, therefore it
is reasonably logical to expect some slope that connects the
steady-state oil temperature of the one limit with the other. I don't
think it reasonable to believe that both steady-state temperatures will
be the same and thus have a zero-slope line in between. This is what
would have to be the case for the oil temperature to be completely
independent of the amount of oil in the engine.


Matt


Matt

[Mike Rapoport]

It doesn't matter how long the oil is in the sump, it only matters how much
heat is lost from the outside of the sump to the air. Do we agree that the
only variable is how great the temperature diffference is between the
surface of the sump and the air? If so, it doesnt matter how long the oil
is in the sump. For your theory to be correct, doesn't the surface of the
sump have to be hotter? Also have you considered that on many engines the
sump is picking up a lot of radiated heat from the exhaust and that there
isn't a lot of airflow over the sump? The outer surface of the sump may
actually be hotter than the oil.

Mike
MU-2


"Matt Whiting" > wrote in message
...
> John_F wrote:
>
> > There are two terms in this temperature equation.
> >
> > One is steady state thermal transfer rate. If you generate a
> > quantity of heat say one BTU then it will raise one quart of oil X
> > degrees F. If you add two times as much heat to the same oil it will
> > raise the temperature of the quart of oil 2X degrees F.
> > At any given RPM the oil pump will pump "Y" quarts of oil per minute
> > whether you have 2 quarts or 10 quarts in the sump since the pump is a
> > gear positive displacement pump. This means that the oil will carry
> > of the SAME amount of heat per minute if the temperature delta is the
> > same. If you want to get rid of more heat then you have to pump the
> > oil faster or heat the oil hotter to get a larger delta temperature
> > difference. This is the steady state condition. This is the condition
> > the engine is in when the temperature gage quits moving up.
>
> Or you start with cooler oil in the sump. This is what, I believe, will
> happen when you have more oil in the engine. The oil has a longer
> residence time in the sump and contacts more surface area of the sump
> through which it may dissipate heat.
>
> Let's run a "thought" experiment at the limits. Let's assume that the
> oil level is so low that no oil is ever in the sump. The oil pump pulls
> it out just as fast as it comes in, just short of the point of sucking
> air. I realize this isn't possible in the real world, but that is why
> this is a thought experiment. In this case, the oil will get very hot
> as it is constantly being circulated through the heads which are one of
> the hottest parts of most engines. The oil has very little opportunity
> to reject heat in the coolest part of the engine, the sump. The
> equilibrium temperature will be rather high.
>
> Now take the other extreme. The oil sump has infinite capacity so the
> oil starts out at the same temperature regardless of how hot the hot
> parts of the engine are. The oil will enter the oil pump relatively
> cool and pick up heat, but will never again get circulated through the
> engine so it has "forever" to dissipate its heat.
>
> A real engine is somewhere in between these to limit cases, therefore it
> is reasonably logical to expect some slope that connects the
> steady-state oil temperature of the one limit with the other. I don't
> think it reasonable to believe that both steady-state temperatures will
> be the same and thus have a zero-slope line in between. This is what
> would have to be the case for the oil temperature to be completely
> independent of the amount of oil in the engine.
>
>
> Matt
>
>
> Matt
>

[John_F]

On Thu, 02 Sep 2004 16:56:03 -0400, Matt Whiting
> wrote:

>John_F wrote:
>
>> There are two terms in this temperature equation.
>>
>> One is steady state thermal transfer rate. If you generate a
>> quantity of heat say one BTU then it will raise one quart of oil X
>> degrees F. If you add two times as much heat to the same oil it will
>> raise the temperature of the quart of oil 2X degrees F.
>> At any given RPM the oil pump will pump "Y" quarts of oil per minute
>> whether you have 2 quarts or 10 quarts in the sump since the pump is a
>> gear positive displacement pump. This means that the oil will carry
>> of the SAME amount of heat per minute if the temperature delta is the
>> same. If you want to get rid of more heat then you have to pump the
>> oil faster or heat the oil hotter to get a larger delta temperature
>> difference. This is the steady state condition. This is the condition
>> the engine is in when the temperature gage quits moving up.
>
>Or you start with cooler oil in the sump. This is what, I believe, will
>happen when you have more oil in the engine. The oil has a longer
>residence time in the sump and contacts more surface area of the sump
>through which it may dissipate heat.

You always START with COOL oil. It just does not stay that way long.
>
>Let's run a "thought" experiment at the limits. Let's assume that the
>oil level is so low that no oil is ever in the sump. The oil pump pulls
>it out just as fast as it comes in, just short of the point of sucking
>air. I realize this isn't possible in the real world, but that is why
>this is a thought experiment.

This is done all the time. It is called a DRY sump and is used on many
aircraft. As far as I know ALL radial use a dry sump.

>In this case, the oil will get very hot
>as it is constantly being circulated through the heads which are one of
>the hottest parts of most engines. The oil has very little opportunity
>to reject heat in the coolest part of the engine, the sump. The
>equilibrium temperature will be rather high.

Nope! That is what the oil cooler is for.

Most oil sumps on Lycoming engines are flat bottomed with vertical
sides. Look at the ratio of the surface area of the bottom to the
sides. It is at least two to one. Aluminum conducts heat MUCH
better than oil so any oil that runs across the bottom of the sump
will get cooling via the bottom and by conduction through the aluminum
up the sides. Most of the heat does NOT go out through the sump but
through the oil COOLER. If you have enough oil in the sump to cover
the oil intake it will be cooled by the bottom surface of the sump.
If you do not believe that cover up your oil cooler and see what will
happen to the oil temperature.
>
>Now take the other extreme. The oil sump has infinite capacity so the
>oil starts out at the same temperature regardless of how hot the hot
>parts of the engine are. The oil will enter the oil pump relatively
>cool and pick up heat, but will never again get circulated through the
>engine so it has "forever" to dissipate its heat.

If you have an infinite oil cooler that will cool the oil back to the
original temperature it still does not matter how much oil is in the
sump.
>
>A real engine is somewhere in between these to limit cases, therefore it
>is reasonably logical to expect some slope that connects the
>steady-state oil temperature of the one limit with the other. I don't
>think it reasonable to believe that both steady-state temperatures will
>be the same and thus have a zero-slope line in between. This is what
>would have to be the case for the oil temperature to be completely
>independent of the amount of oil in the engine.

There may be a small slope but it may be positive not negative since
the extra oil gets tossed around more and heats up due to mechanical
splashing.

Applying some simple math:
Since 90 % of the heat that is carried by the oil is lost in the oil
cooler not the sump you would expect that if the quantity of heat
carried away by the sump doubled the oil temperature would only drop
50% of 10% which is 5%.


>
>
>Matt
>
>
>Matt

Here is an actual thing that happened to me.
I loaned one of my lawn mowers to a neighbor. He misread the oil
level dip stick and added half a quart too much oil. The extra oil
covered the bottom of the crank shaft and the bottom of the piston.
The extra splashing caused the oil to get so hot that the crank case
melted the ignition kill wire that went to the key switch grounding
out the ignition which killed the engine before more damage was done.
This wire had lain on same spot of the crankcase for hundreds of
hours and never melted until the oil level was over filled.

More oil caused the engine to get hotter not cooler.

John

[Matt Whiting]

Mike Rapoport wrote:

> It doesn't matter how long the oil is in the sump, it only matters how much
> heat is lost from the outside of the sump to the air. Do we agree that the
> only variable is how great the temperature diffference is between the
> surface of the sump and the air? If so, it doesnt matter how long the oil
> is in the sump. For your theory to be correct, doesn't the surface of the
> sump have to be hotter? Also have you considered that on many engines the
> sump is picking up a lot of radiated heat from the exhaust and that there
> isn't a lot of airflow over the sump? The outer surface of the sump may
> actually be hotter than the oil.

Yes, we agree that what matters is the heat lost from the sump to the
surrounding air, although I'd say more specific to our discussion is the
heat lost from the oil to the sump to the outside air.

Again, I'd add a second variable and that is the difference between the
temperature of the oil and that of the sump and then the sump vs. that
of the air.

Yes, my theory is dependent on the assumption that the temperature of
the oil entering the sump exceeds the temperature of the sump walls
themselves. If not, then the oil will not contribute at all to cooling
the engine, except in the obvious and trivial case of preventing the
friction that would otherwise heat the engine to failure within seconds.
It would likely still contribute to equalizing the temperature of the
engine by moving heat around as it flows, but as you say, it would not
contribute to any net cooling of the engine if your assumption is correct.

I honestly don't know if the sump is losing or gaining heat in net in
the engine compartment. I suspect the sump is the coolest part of the
engine, but I have no data either confirm or deny that premise. I did
some searching the other night and couldn't find anything substantial
regarding the temperatures of relative locations of an aircraft engine
or anything about the effect of more of less oil on engine cooling
capability.


Matt

[Matt Whiting]

John_F wrote:

> On Thu, 02 Sep 2004 16:56:03 -0400, Matt Whiting
> > wrote:
>
>
>>John_F wrote:
>>
>>
>>>There are two terms in this temperature equation.
>>>
>>>One is steady state thermal transfer rate. If you generate a
>>>quantity of heat say one BTU then it will raise one quart of oil X
>>>degrees F. If you add two times as much heat to the same oil it will
>>>raise the temperature of the quart of oil 2X degrees F.
>>>At any given RPM the oil pump will pump "Y" quarts of oil per minute
>>>whether you have 2 quarts or 10 quarts in the sump since the pump is a
>>>gear positive displacement pump. This means that the oil will carry
>>>of the SAME amount of heat per minute if the temperature delta is the
>>>same. If you want to get rid of more heat then you have to pump the
>>>oil faster or heat the oil hotter to get a larger delta temperature
>>>difference. This is the steady state condition. This is the condition
>>>the engine is in when the temperature gage quits moving up.
>>
>>Or you start with cooler oil in the sump. This is what, I believe, will
>>happen when you have more oil in the engine. The oil has a longer
>>residence time in the sump and contacts more surface area of the sump
>>through which it may dissipate heat.
>
>
> You always START with COOL oil. It just does not stay that way long.

I didn't mean start as in first starting the engine. I meant start as
in the oil pump is starting out with cooler oil at its intake if there
is more oil in the sump and it has resided there longer to dissipate its
heat to the sump.



>>Let's run a "thought" experiment at the limits. Let's assume that the
>>oil level is so low that no oil is ever in the sump. The oil pump pulls
>>it out just as fast as it comes in, just short of the point of sucking
>>air. I realize this isn't possible in the real world, but that is why
>>this is a thought experiment.
>
>
> This is done all the time. It is called a DRY sump and is used on many
> aircraft. As far as I know ALL radial use a dry sump.

You are really showing your ignorance now. A dry sump system doesn't
mean that there is no reservoir of oil, it just isn't in the sump, but
is remotely located. This actually gives better oil cooling typically
as the oil reservoir often isn't even connected to the engine. You may
want to read a little at the following link. It not only explains
different oiling systems, but is also states that oil serves a cooling
function in an engine.
http://www.geocities.com/zuuba_2000/Aeromat.html



>>In this case, the oil will get very hot
>>as it is constantly being circulated through the heads which are one of
>>the hottest parts of most engines. The oil has very little opportunity
>>to reject heat in the coolest part of the engine, the sump. The
>>equilibrium temperature will be rather high.
>
>
> Nope! That is what the oil cooler is for.

Heat doesn't care where it's at, it always moves from a hotter location
to a cooler location. Sure, the oil cooler is made to cool the oil, but
the oil will still lose heat anywhere in which the oil temperature is
higher than the surroundings. This can be in the sump or can be in a
remote oil tank as with dry sump systems.



> Most oil sumps on Lycoming engines are flat bottomed with vertical
> sides. Look at the ratio of the surface area of the bottom to the
> sides. It is at least two to one. Aluminum conducts heat MUCH
> better than oil so any oil that runs across the bottom of the sump
> will get cooling via the bottom and by conduction through the aluminum
> up the sides. Most of the heat does NOT go out through the sump but
> through the oil COOLER. If you have enough oil in the sump to cover
> the oil intake it will be cooled by the bottom surface of the sump.
> If you do not believe that cover up your oil cooler and see what will
> happen to the oil temperature.

I never said that most of the heat goes out through the sump. I said
that SOME heat does. And I said that MORE heat will be rejected as the
contact area between the oil and the sump increases. Sure the bottom
has a lot of area in contact, but if you raise the oil level it will
lose even more heat due to contact with the sides of the sump. More
heat loss equals lower oil temperature and greater engine cooling by the
oil.



>>Now take the other extreme. The oil sump has infinite capacity so the
>>oil starts out at the same temperature regardless of how hot the hot
>>parts of the engine are. The oil will enter the oil pump relatively
>>cool and pick up heat, but will never again get circulated through the
>>engine so it has "forever" to dissipate its heat.
>
>
> If you have an infinite oil cooler that will cool the oil back to the
> original temperature it still does not matter how much oil is in the
> sump.

True, what is your point?


>>A real engine is somewhere in between these to limit cases, therefore it
>>is reasonably logical to expect some slope that connects the
>>steady-state oil temperature of the one limit with the other. I don't
>>think it reasonable to believe that both steady-state temperatures will
>>be the same and thus have a zero-slope line in between. This is what
>>would have to be the case for the oil temperature to be completely
>>independent of the amount of oil in the engine.
>
>
> There may be a small slope but it may be positive not negative since
> the extra oil gets tossed around more and heats up due to mechanical
> splashing.

Wrong. If any significant splashing occurs due to contact with the
crank, the oil will aerate, the oil pump will cavitate and the engine
will fail shortly thereafter.



> Applying some simple math:
> Since 90 % of the heat that is carried by the oil is lost in the oil
> cooler not the sump you would expect that if the quantity of heat
> carried away by the sump doubled the oil temperature would only drop
> 50% of 10% which is 5%.

What is your source for the 90% figure? 5% is still 5% and will result
in increased engine cooling as the oil level increases. It may well be
a small number, but any extra cooling at all is significant as the life
expectancy of oil drops dramatically with increasing temperature.


Matt