M20 Air/Oil separator

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.

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"

"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

"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...

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" wrote in message nk.net...
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

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?

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

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

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