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IO360 oil leak/blow by

P

Pat Stewart

Well Known Member
Been struggling to find the source of about a tablespoon of oil on my belly after every flight. This engine has about 58 hours on it. I brought the oil level down to about 6.5 and still have oil. I can find no sign of any leak (yes it's a Lycoming) around the engine so assuming it's blow by. No staining on the top of the exhaust were the blow by tube is located so that's interesting. This engine also has an oil separator.

Thoughts would be appreciated.
 
Rocker Cover gaskets?

I chased an oil leak for months and even went so far as to add fluorescent dye to the oil to try and pin down the source. It turned out to be one of the rocker cover gaskets.
 
Don't hesitate to run it BETWEEN 5-6 quarts. I find that over 6 qts and it will blow out.
And with only 58 hours you might still be getting some blowby past the rings.

Vic
 
Oil level.

Lycoming says 4 quarts is minimum.
Like Vic said,
Mine likes it best at 6 quarts. Add at 5 quarts.
 
This is all good info for me, for the first year or two I would add oil when I got to about 7 Qt, now I add oil when I get to 6. Maybe I should let it go farther down. I don't have awful a lot of oil on the belly but recently seen a small strain of oil that I can not find the source.
 
edsong said:
Lycoming says 4 quarts is minimum.
Like Vic said,
Mine likes it best at 6 quarts. Add at 5 quarts.
Click to expand...

Unless you have a IO-360-M1A/B or HIO-360-G1A Lyc 360, the actual specification given by Lycoming is only 2 qts. minimum.

I also find my O-360 is happier at 6 qts. Any more and it seems to auto-correct to the 6 qts. number anyway...:)
 
Pat Stewart said:
Been struggling to find the source of about a tablespoon of oil on my belly after every flight. This engine has about 58 hours on it. I brought the oil level down to about 6.5 and still have oil. I can find no sign of any leak (yes it's a Lycoming) around the engine so assuming it's blow by. No staining on the top of the exhaust were the blow by tube is located so that's interesting. This engine also has an oil separator.

Thoughts would be appreciated.
Click to expand...

I finally figured out and got comfortable with 6 quarts in my RV7A/IO360M1B.
Very stable there. More than that, it just blows out the vent. I also have a oil separator.
 
I fought oil leaks early on with my 0360 6A. I replaced front seal, went through all the usual suspect places such as oil screen plug, mag gaskets, vernatherm gasket, etc. I added the ASA oil seperator. Still a wet belly.

I consider 6 qts full and add at 5.

Turned out to be the mechanical fuel pump. Not where it mounts to the crankcase, but it was leaking oil out of the vent line between the two diaphragms. I replaced the pump and I have not seen a drop anywhere for the past 50 hours. My engine is dry as a bone and I'm a happy camper.
 
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