M20 air/oil separator install

[1524J]

Hey all....hoping someone can help me w/ a M20 air/oil separator install. Instructions state the best location for the return line off the M20 is to a low pressure port on the accessory case. I've been unable to locate a low pressure port on my A3B6D engine. The three other options are 1) welding a "Y" to the oil return line off the #4 cylinder 2) Tying into the rocker cover box 3) tying into the oil fill tube. It doesn't appear to me that I'd have near the recommended down angle required if I try #2 or #3, although from what I've reseached, #2 appears to be the method of choice. Any suggestions would be appreciated!

[Piloto]

I have mine connected to the valve cover thru an elbow fitting. I mounted the elbow at the lowest point on the cover. It works very well. The separator itself has to be mounted as high as possible to assure good drainage. I have absolutley no oil discharge on the vent and oil consumption at 8 qts is 9hrs/qt. Engine is 400hr SMOH.

José

 

 

[1524J]

Appreciate the input Jose'. I noticed the instructions said to install the elbow fitting in the valve cover box on the centerline of the cover. I plan on mounting my M20 behind the oil cooler but closer to the firewall as high as I can get it w/out it contacting the cowl. That puts me running the drain line off the separator under the oil cooler. It doesn't appear that I would have any noticeable down slope once I pass the oil cooler to the valve cover. How have you routed your drain line from the separater to the valve cover?

[MooneyMitch]

Below is a quote from Sacramento Sky Ranch.  I found the #3 reason interesting.

 

Editorial about air/oil separators

Some of you have asked why I don't sell Air/Oil Separators. When used to capture engine breather oil residue there are several concerns:

1. The amount of oil out the engine breather is a useful indication of engine problems. The air/oil separator takes away this indicator

2. Air/Oil separators of small size may freeze up. This has caused accidents where the pressures blew the crankcase nose seal out of the engine resulting in loss of engine oil. A byproduct of combustion is water.

3. Air/Oil separators are like hooking a line up to your anus and piping it back into your mouth. Excuse the crude analogy but who wants the water, acids and other combustion residuals pumped back into ones engine.

[1524J]

Alright Mitch......after reason #3 I'm sending my M20 back!!! lol   Seriously though....oil  loss through the

[1524J]

Alright Mitch......after reason #3 I'm sending my M20 back!!! lol Seriously though....oil loss through the crankcase breather and being able to track that oil loss would be a compelling reason for me. It's just not enough because I'm tired of cleaning the oil off the belly of my baby!! I'm not convinced that the oil lost through the crankcase breather would have any more contaminates than the oil recirculated back through the system. I figure that's why we have filters and we change our oil on a regular basis. Although I quess the argument could be made that if your losing enough oil through the crankcase breather, all you need to do is change the filter every once in a while as the oil is constantly being changed. I think I tried using that logic w/ my father once on the first car I had. For some reason, he didn't seem to agree w/ my train of thought.

[MooneyMitch]

I'm just sayin'.......... 

[RJBrown]

Shortly after buying my first plane, 231NH, I noticed oil increasing on the belly. The MSC sold me a M20 separator. The problem was a worn engine. All the separator did was mask the problem. Once the plane was fixed properly the separator was not reinstalled. A total waste of money.

[1524J]

Randy, how did you determine your engine was worn out? Through compression readings? After you "fixed" the problem, did you not have the "oil on the belly" problem that plagues most us. I'm not trying to argue, but for me it's just a matter of convenience for which I am willing to pay. I take compression readings every 50 or so hours, change my oil every 25 hours and send in an oil sample every other change. I'm comfortable that I take steps to "know" the condition of my engine. I quess it just boils down to preference. This is my second Mooney and I've fought oil on the belly enough that I'm willing to try something else.

[Shadrach]

The biggest benefit that I can see to using the Air/oil seperator is that from what I've heard, it minimizes oil blow out when filling the crank case to higher levels. My IO360 tends to blow out anything more than about 6.5 quarts in short order (2-3hrs). Oil loss from 6.5qts to 5.5qts takes ~12hrs or more depending on how the plane is being operated. I've heard it said that with a seperator you can actually run at 7 to 8 qts without puking it out through the breather.

[1524J]

Quote: Shadrach

The biggest benefit that I can see to using the Air/oil seperator is that from what I've heard, it minimizes oil blow out when filling the crank case to higher levels. My IO360 tends to blow out anything more than about 6.5 quarts in short order (2-3hrs). Oil loss from 6.5qts to 5.5qts takes ~12hrs or more depending on how the plane is being operated. I've heard it said that with a seperator you can actually run at 7 to 8 qts without puking it out through the breather.

[1524J]

Quote: Shadrach

The biggest benefit that I can see to using the Air/oil seperator is that from what I've heard, it minimizes oil blow out when filling the crank case to higher levels. My IO360 tends to blow out anything more than about 6.5 quarts in short order (2-3hrs). Oil loss from 6.5qts to 5.5qts takes ~12hrs or more depending on how the plane is being operated. I've heard it said that with a seperator you can actually run at 7 to 8 qts without puking it out through the breather.

[RJBrown]

Bought at 1100 hours and the blessing of the MSC. Over the next 100 hour it really started using oil. At the end it went through 5 quarts of oil in one hour. The engine was replaced with a TSIO520 at 1200 hour. After the Rocket conversion there was no oil on the belly.

Next 800+ hour were oil free on the belly. I believe that oil on the belly is caused by 2 things #1 too much oil in the engine and #2 a worn engine.

EDIT

Shadrach may be right about keeping 7+ quarts IN the engine.

[Piloto]

Quote: Mitch

Below is a quote from Sacramento Sky Ranch.

[Piloto]

Quote: Mitch

Below is a quote from Sacramento Sky Ranch. I found the #3 reason interesting.

 

Editorial about air/oil separators

Some of you have asked why I don't sell Air/Oil Separators. When used to capture engine breather oil residue there are several concerns:

1. The amount of oil out the engine breather is a useful indication of engine problems. The air/oil separator takes away this indicator

2. Air/Oil separators of small size may freeze up. This has caused accidents where the pressures blew the crankcase nose seal out of the engine resulting in loss of engine oil. A byproduct of combustion is water.

3. Air/Oil separators are like hooking a line up to your anus and piping it back into your mouth. Excuse the crude analogy but who wants the water, acids and other combustion residuals pumped back into ones engine.

[Piloto]

Quote: 1524J

Appreciate the input Jose'. I noticed the instructions said to install the elbow fitting in the valve cover box on the centerline of the cover. I plan on mounting my M20 behind the oil cooler but closer to the firewall as high as I can get it w/out it contacting the cowl. That puts me running the drain line off the separator under the oil cooler. It doesn't appear that I would have any noticeable down slope once I pass the oil cooler to the valve cover. How have you routed your drain line from the separater to the valve cover?

[Piloto]

Quote: 1524J

Appreciate the input Jose'. I noticed the instructions said to install the elbow fitting in the valve cover box on the centerline of the cover. I plan on mounting my M20 behind the oil cooler but closer to the firewall as high as I can get it w/out it contacting the cowl. That puts me running the drain line off the separator under the oil cooler. It doesn't appear that I would have any noticeable down slope once I pass the oil cooler to the valve cover. How have you routed your drain line from the separater to the valve cover?

[John Pleisse]

I fill to 7, the M20 seperator keeps just about everything 7 and below off the belly. Anything above 7 will still blow over. Prior to the M20 installation,  all oil went down the belly.

[jetdriven]

Ross:

Our 1400 SMOH field overhauled engine does exactly as your does. Running at 2400 RPM cruise gets another couple hours per quart than 2500 RPM.

That 400$ M20 separator can buy around 85 quarts of oil and thats if you install it yourself.  At 12 hours per quart (lost) thats 1000 hours worth of oil on the belly.

Of course you have to wash it.  But still...

Quote: Shadrach

The biggest benefit that I can see to using the Air/oil seperator is that from what I've heard, it minimizes oil blow out when filling the crank case to higher levels. My IO360 tends to blow out anything more than about 6.5 quarts in short order (2-3hrs). Oil loss from 6.5qts to 5.5qts takes ~12hrs or more depending on how the plane is being operated. I've heard it said that with a seperator you can actually run at 7 to 8 qts without puking it out through the breather.