Exhaust leaking

My #2 exhaust seems to be leaking what appears to be oil coming through the slip joint of the exhaust. I talked to Larry Vetterman who has never seen this and Mahlon at Mattituck who built the engine, ECI.

It started about 40 hours into flying and cleans off with acetone. Engine has 105 hours now and good compression, 78/80. Oil burn is about one quart in8 hours. Any help in letting me know what's going on would be appreciated.

Is that being blown back up from inside the exhaust? It sure looks like something is dripping on the exhaust from the exterior.

I had the same thought as Jim - sure looks to me like an external drip on to the pipe!

X3, what they said.

Look for a valve cover gasket, or oil return line problem.

Ironflight said:

I had the same thought as Jim - sure looks to me like an external drip on to the pipe!

Click to expand...

That would explain the higher than normal oil consumption for an ECI motor that will normally get 25+ hours per quart.

During flight, the oil drip is burned away and consumed. What you see there is the results of oil dripping on a cooler pipe.

Thanks for the comments. When I took this picture I was at the start of a conditional inspection so had checked for leaks but the engine is bone dry. One hangar mate had suggested maybe a valve guide was loose but I'm not an engine guy so can say or explain how the oil is working its way through the slip joint. I plan to fly it for a few hours and pull the cowl again and check for leaks.

Thanks again,

If you just drop that exhaust you'll know right away whether its bubbling out or being dripped on. If you have an oily exhaust port you'll see it. Otherwise its almost gotta be a rocker cover or push rod shroud or somehtin'.

I don't think that's an external leak. It has to be blustery as can be under that cowl at speed and altitude. The oil in the picture is just oh-so-concentrated at the exhaust joint and down. If it were an external leak from above, those pipes and the bottom cowl would have random schmakles of oil everywhere.

Is it possible that there is enough of an exhaust restriction or (since this is a crossover system) reversal of the exhaust during the other cylinder's exhaust stroke to puff oil out of the joint?

And yes, my two cents are on the exhaust valve stem. An intake valve stem, head gasket, or piston ring oil leak wouldn't leave that much oil in my minds eye after it had to suffer through cylinder combustion. But, I'm not an A&P.

In any event, keep an eye on those oil pressures.

aerhed

What he said.

Interesting deposits...

Was this noticed after any of the 1st flights or did it develop later on?

Does the engine exhibit any sort of "Morning Sickness" tendancies. I'm suspecting worn/scored/stuck exhaust valve leaking on the inside of the pipe after shutdown. My theory is initially after start, it pukes oil out of the joint due to opposite cylinder backpressure, and then 'smoothes out', leaving the burned deposits).

Check the exhaust pipe end(s) prior to your next flight after the aircraft has sat for a while. Are they oily? If they have light gray deposits then the oil may be originating from external sources.

Due to the turbulated air in the cowl, the oil source can sometimes be found in some strange areas. In this pic the oil doesn't appear to be sprayed around at all indicating a close single source. There also is not any sign of the leak further down by the eyeball joint.

Let us know what you find out...

Do you have anything tied to the valvecover screws.
Do you have anything raped with that black plastic spiral wire guard.
If so. This material can melt and turns into what looks like grease. I have seen it start to show up because of the extreme heat we are having.
Check it out.

Thanks for the last few posts. I have been hesitant to drop the exhaust (due to laziness) and look inside the pipe and exhaust port. Will do that this weekend and let you know.

Thanks