[CharlieWaffles]

I have about 50 hours on my IO-540 and recently had the top cowl off for an inspection. I noticed there was some light oil traces near the base of one or two jugs. I know the Lycomings are notorious for leaking and I'd like to just write this off as that. But not having the first hand experience of how much leaking is normal, please pardon this possibly excessive post. The oil appears near the nut on the upper right of the jug. Thoughts?

 

[BGS]

Mark, I had some of the same leaks. If you look at the rocker tubes where they insert into the engine block, you do have a bit of oil on one. A couple of my tubes were leaking in the same spot and was due to the tubes not pushed in all the way. The local A&P stopped over and removed the rocker covers and reset all the tubes. No more leaks.

 

[rocketbob]

There is a stamping that is press fit into the tappet bore holes in the case. These will leak over time, and these are what the pushrod seals fit into. When I overhaul an engine I smear proseal on these before I tap them into the case. So replacing the pushrod seals may or may not fix a leak there.

 

[jchang10]

Here are my 2 other future sources of oil leaks from a factory new lycoming.

1. Around 200 hours, i noticed oil drops at the bottom of the valve covers. The paper valve cover gaskets are junk. I replaced them with silicon gaskets.

Unfortunately, i have a bit of cooked brown/black oil on my nice new cylinder heads. Anyone have an idea of how to clean these spots?

2. The oil return tubes under each cylinder attached with rubber hosing and worm clamps seem to persistently have an oil drop on them. A friend of mine said that no matter how tight you tighten the worm clamps, they will never form a perfect "round" seal because of the straight worm drive. That made sense to me. Thus, i stopped bothering trying to stop this leak.

Jae