Oil Leak or Cracked Cylinder?

[WAFI]

After a two hour flight and back in the hanger I noticed a some oil streaks down the pilot side of my plane. I removed the cowlings and found that there was oil surrounding my #4 exhaust port and also up underneath the push rod tube that is covered up by the aluminum baffling. My firsts assumption was that the push rod tube green gasket was leaking oil down the cylinder but in the back of my mind I am worried that it might be a cracked cylinder. Thoughts....??? @M20Doc

Absolutely no change on my engine monitor, all cylinders temps are great!

[N201MKTurbo]

It is most likely the push rod tubes. If you think it is a cylinder crack, remove the valve cover and look inside. Any crack that is leaking oil would have to be visible in there. It isn't a common place for a cylinder to crack.

[Guest]

8 hours ago, WAFI said:

After a two hour flight and back in the hanger I noticed a some oil streaks down the pilot side of my plane. I removed the cowlings and found that there was oil surrounding my #4 exhaust port and also up underneath the push rod tube that is covered up by the aluminum baffling. My firsts assumption was that the push rod tube green gasket was leaking oil down the cylinder but in the back of my mind I am worried that it might be a cracked cylinder. Thoughts....??? @M20Doc

Absolutely no change on my engine monitor, all cylinders temps are great!

Either a leaking pushrod tube seal or a leaking rocker cover gasket. Highly unlikely that it’s a cracked head, but never say never.

[PT20J]

I had the same thing, but not as bad, and it was the cork gasket on the rocker cover that my Lycoming rebuilt came from the factory with. I'm changing them out to silicone gaskets soon.

[carusoam]

Rocker cover gaskets are easy to swap out…

Tubes that connect the rocker drains… often have ancient hose clamps… get new ones.

Replacing hoses and gaskets and clamps solved a bunch of leaks on my O360…

I think Lycoming has a kit for a lot of these parts, available through aircraft spruce…

Tightening things up properly may help as well… proper torque values and order of tightening may apply.

PP thoughts only, concurring with everyone else…

Best regards,

-a-

[WAFI]

I changed out the green push rod tube o-ring / gasket and flew for about two hours with no leaks. Done!