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Posted

i would start by trying to identify where is the oil leaking from before considering installing one.

plenty of threads on where the oil that end up on the gear doors can come from.

my view is that mooney's engine compartment is crowded enough that if you don't need to have an accessory in there, don't install it.

Posted

Hoping I don't need one. My engine is out right now repairing a crack in the case. So when I comes home I hope for a nice clen engine that does not leak !

Posted

That doesn't look like oil that would be held back by a separator...

That looks like something more important...

Unless you keep filling to the max, knowing a quart will be pressed out of the vent?

Best regards,

-a-

Posted
looks likes like this after every flight + a greasy belly. AP says no obvious leak. i did a search but no topics on the subject. they are $599. post-8629-0-63307300-1359950643_thumb.jp
I've never seen that much oil after any flight. All coming from the breather?
Posted

if you don't mind getting your hands dirty:

 

remove the cowling (top and bottom) ... stodart solvent and rugs .... clean everything very well

 

run the engine on the ground a few minutes and see what happens (where the oil is coming from

 

if you cannot see the sources, re-cowl and fly in the pattern once and see what happens  

 

 

unless you are over-filling, i doubt all that oil is from the breather.

 

just think it is too early to look at an oil separator yet.

Posted

Good advise above.....that's your plane telling a lot more than it has a dirty belly. Uncowl, clean it up, check for loose fittings, use some baby powder, run her up, and check everything closely.

 

If you don't find anything, the once around the circuit suggestion is a good one. Then check again.

 

Good luck!

Posted

I had an M20 oil separator for the last 10 years and found it to be effective not only on keeping the belly clean but on reducing the oil consumption when full at eight qts (IO-360). At 8qts it burns 1qt every 10 hours. The trick to make it work properly is on the installation. Make sure the inlet to the M20 is higher than the breather outlet. No holes on the exhaust line. The working principle is that the condensed/trapped oil in the canister is discharged back to the engine when the engine is off (no cranckcase pressure). To properly measure oil consumption you have to allow a week or more to allow oil from the M20 canister and engine upper part to drain back to the crankcase.

Other than breather oil most common oil leaks are due to valve cover gaskets and cylinder oil return hoses. For the valve covers most new or overhauled engines comes with cork gaskets. They will leak within 100hrs. Have the gaskets replaced with the orange rubber type. They will last the life of the engine. The short oil return hoses clamp need to be tighten at every annual, specially if they are over 5 years old.

The crankcase is made out of a casting process which due to grain size used it can cause some minimal degree of porosity tha can cause a new case to leak. Normally the manufacturer will check for these but not the typical overhaul shop. A leak may show on a side wall of the case but you may think is from the above bolts. You put sealant on the above seam/bolts but the leak still showing up in the same area. But if you look closely to the wall you will notice some degree of granularity greater than the rest. If you notice this remove the paint in the area and apply Marine-Tex or any other good sealer. I use Marine-Tex from my good experience with it on fixing leaks on marine Caterpillar engines.

José

Posted

I agree with others here; this is your engine talking and something needs to be done.  When this happened on my airplane I was getting excessive blow-by past the rings and the crankcase was pressurizing.  This will be pretty obvious if the oil turns black right after doing an oil change.  Mine was black after 4 hours with new oil and I was loosing about 1 qt every 2 hours - all of it being blown out the breather and onto the belly.  Mine was so bad it would drip oil off the tail tie down after a 2 hour flight.

 

In my particular case, I had to replace all the cylinders to fix the problem.  All the cylinders were corroded (from sitting before I bought the airplane) and could not even be overhauled!  New cylinders and I'm back to 1 qt every 10 hours and life is good - except all that missing money :)  By the way, all the compression checks were still within Continental specs.  I'm just saying you can't always know from a compression check alone.

Posted

I never fill to 8 quarts.  I try to keep between 6 and 7 quarts, otherwise it just blows out.  When I bought the plane the owner who had owned it since new told me from day one it blew out the oil down to 6.5 qts and then very little afterward.  Sure enough when I fill to 7 qts it burns half a quart in 2-3 hours and the other half in 7 to 8 hours leaving me with one quart of oil every 10-11 hours of flight.  Compressions are good and oil usage is very steady.  But if I fill to 8 quarts it will blow out to 6.5 quarts in less than 5 hours.  No point in wasting good oil.

Posted
I never fill to 8 quarts.  I try to keep between 6 and 7 quarts, otherwise it just blows out.  When I bought the plane the owner who had owned it since new told me from day one it blew out the oil down to 6.5 qts and then very little afterward.  Sure enough when I fill to 7 qts it burns half a quart in 2-3 hours and the other half in 7 to 8 hours leaving me with one quart of oil every 10-11 hours of flight.  Compressions are good and oil usage is very steady.  But if I fill to 8 quarts it will blow out to 6.5 quarts in less than 5 hours.  No point in wasting good oil.

Same here. 6.5 seems to be the magic quantity. I always found it interesting how little is required in these engines as well (if I recall correctly, 2 quarts is the minimum in the Lycoming manual). Not that i would fly that way, but it seems to be an awfully low number.

Posted

My f was the same way. I always ran it at 6.5 and added when it went down to 5.5. I was thinking of an oil seperator untill I read brians article and now am thinking of taking it off on my m20s.

Posted

My f was the same way. I always ran it at 6.5 and added when it went down to 5.5. I was thinking of an oil seperator untill I read brians article and now am thinking of taking it off on my m20s.

Question for you in letting it drop to 5.5.  Have you noticed on the ground after a flight when the oil is hot what your oil pressure is?  When I get below 6 qts the oil pressure is in the yellow on the ground after a flight.  Just curious if you see the same thing.  I had an MSC one time tell me he didn't like that and then another time he said it exactly what I should expect.

Posted

I have a rocket. i dont let the oil get below 8 . my A/P said the air oil separator is designed for a 4 cylinder which makes sense. i installed  the airwolf and we'll see how it goes. it doesnt look like it will impede airflow . I just had the annual and the compressions where low end of normal. there wasnt a lot of oil in the cowling.  it seems to do it less at 8 quarts than at 11. 

Posted

oil press will drop off when hot and at idle rpm. nowhere near lycs min hot oil specs. I don't know what the specs are on your cont, but i would expect to to drop considerably hot at idle also. I use phillips 20-50 in the f and shell 15-50 in the s.

Posted

According to one popular aviation columnist, running an oil separator is like "hooking a tube from your butt to your mouth".  I think he was referring to the acids in the blowby getting recycled into the crankcase. 

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