Is this normal? Rotax 503.

[Captdill]

Is this normal? Rotax 503, oil between fins on head. Do you have it? Where is it coming from?

[t j]

I had that happen from a blown exhaust gasket. One of the gaskets inside the fan cowling.

503's seem to have a lot of oil in the exhaust and the fan blows it through the fins on the heads.

I had taken the exhaust Y off to check the rings on the exhaust side and only replaced the 2 outside gaskets between the fan cowl and the exhaust Y.

I thought I would get away with not replacing the 2 inside gaskets between the cylinders and the fan cowling being that I didn't take the cowling off but no.

[Captdill]

I had that happen from a blown exhaust gasket. One of the gaskets inside the fan cowling.

503's seem to have a lot of oil in the exhaust and the fan blows it through the fins on the heads.

I had taken the exhaust Y off to check the rings on the exhaust side and only replaced the 2 outside gaskets between the fan cowl and the exhaust Y.

I thought I would get away with not replacing the 2 inside gaskets between the cylinders and the fan cowling being that I didn't take the cowling off but no.

We did that inspection last annual, pretty sure we used new gaskets. Of course this shot is from the intake side rather than exhaust, but I suppose with fan air the oil can be migrating over there. Tom, tell me again just to confirm, the oil you sourced from the exhaust made it over to the intake side of the heads?

If I can rule out cracked heads, I can relax.

Thanks.

[t j]

Yes, oil from the leaking exhaust gasket made it over to the intake side of the heads.

Another thing to check is spark plugs for proper torque. Your left cylinder has the cylinder head temp ring. I have had oil from those leaking too. Although not as much.

[t j]

Jeff, I did some searching and found this https://www.recreationalflying.com/threads/503-150-hr-inspections.1294/
A couple guys think oil on the top of the head on a 503 is coming up from the crankcase. It is migrating up a cylinder stud. Something else to check I guess.

[Captdill]

Thanks Tom, your answers are a relief.