M20 Air/Oil separator

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,

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

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"

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"

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
--------------------

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

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"