Air/oil separators

[231Pilot]

I was looking at the M20 air/oil separator web page

http://www.m-20turbos.com/content/products/breather.php?link=breather

and I was curious as to what the MooneySpace member experience has been with them.  I liked the claim of better cooling and less oil loss...have you found these claims to be valid?  Is the product worth the price and cost of installation?  It would be a very strange experience to fly a Lycoming that would keep more than 6 qts. of oil.

[Ned Gravel]

Lew:

I have had mixed success with mine and it was on the engine when I bought the aircraft in 2005.  I started by trying to keep the oil up to 7 qts.  Always had a greasy belly, which only really slowed down when it was decided that the oil level could be OK if held between 5.5 and 6 qts.  Oil consumption changed from 1 qt every 4 hours to 1 qt every 8 hrs. 

Air/oil separator did not really help in that situation.  But I kept it.  After the overhaul last spring, it was decided to put a condensate bowl in the return line, and that is now collecting the condensate from the air/oil separator.  Kept our engine shop guy happy because he does not trust air/oil separator.  The new bowl does collect condensate and I empty it every oil change (25 hrs).  The air/oil separator also has some finicky placement requirements so that it works properly regarding bends in the lines and height of the device itself with respect to the engine.

One argument I have not been able to resolve is whether the differences in volume (capacity) of Bill Sandman's M20 device and the Air Wolf one (http://www.airwolf.com/Products_AirOilSeparators.htm) actually make a difference in operating capability of the device.  Don't really care (I am going to keep my M20) because there is not enough room inside the cowl for the Air Wolf device.

But it would be good to know.

BTW:  Yours is the first comment I have heard (from another Mooney driver) that our Lycomings do not like to hold on to more than 6 qts at a time.  Interesting.

Hope this helps.

[231Pilot]

As to the 6 qts., both my M20C, and my M20J created their own upper limit of 6 qts.  Each would lose the 2 qts. within the first few hours of flying, then would hold level at 6 qts. requiring the addition of 1/2 qt. periodically.  The engines always consumed oil, but the top 2 qts. never stayed long.

[Piloto]

I have the M20 and I am happy with it. The trick to make it work is to have it installed above the engine breather. I typically keep my IO-360 between 7 and 8 qts with no vsible discharge on the breather line or belly, neither any significant oil comsumption. Oil comsumption varies between 7 to 8 hours per qt (at 8qts). For the M20 proper operation it is important that the discharge line open end faces aft behind the cowl flaps. Also no openings on the line inside the cowling area. This will insure low cranckase pressure thus reducing oil burn. I have the oil return line connected to the valve cover instead of the clylinder return line. The M20 is factory standard on new Mooneys.

José

 

[Parker_Woodruff]

The M-20 was installed on mine when I bought it.

I always fly mine between 5.5 and 6 quarts so I really don't know how well it works.

[airkraft]

Installation is critical to the success of an M20.  We've repositioned ours twice and now have it spot-on, apparently.  I'm at 7 Qts. now after about 15 hours since last oil change of 8 Qts.  The separator was on the a/c when we bought it. 

I like to run 8 Qts.  I'm sure 6 Qts. is perfectly fine.  I've even been advised by one knowledgeable pilot that running the oil below maximum quantity allows the engine to run cooler.  Not sure how that works.  Oil cooler is more efficient? Our C172(O-320E2D) starts at 8 and runs down to 6 and holds there (no M20).  Just my two cents...GK

[seebruce]

Check your oil filler cap. I found that my plane would blow oil down to 5.5 qts. when I bought it. I noticed that the filler cap was very loose. I doubled up on the gasket and the problem went away. I believe that because of the extremely high positive pressure inside the tightly cowled engine compartment the crankcase was being pressurized through the oil filler. Also check the dipstick o-ring.

[seebruce]

Sorry guys, my post applies to a turbo.

[J0nathan225]

9 year revival:

I have an M-20 seperator installed on my Mooney and I have started running an engine saver on it.  After speaking with them I just want to make sure I'm realizing the benefits of pumping dry air into the engine.

 

Does the M-20 have a one-way flap/valve, which would prevent the pumping of the dry air into the case like mentioned in the below response?

 

" For the most part our unit should blow right through the separator when plugged into the breather hose.

The only issue I have heard of is the possibility of a one way valve or flap between the separator and engine.

Most of the time there is just a screen between the two and our unit will push air right through.

 

If you are putting the air into the oil fill you may want to plug the breather line. Our unit works by filling the engine with dry air and then maintaining a slight internal pressure to keep the outside air from coming back in. If it is open from the engine out the breather there is a good chance the air is escaping out the breather and not keeping the engine filled as it should.  "

 

Apparently that email on the M20 site no longer works.