|
Hi
Guys,
I've
been chasing an oil leak for a while now. It only happens when the engine is
running. When I get back from a 20 minute flight the cowl has oil streaks down
the outside, everything under the cowl has an oil film on it, and the turbo
is seriously smokin'. I could probably make a similar mess by spraying
about 1/2 cup of oil at the cowl and engine.
Today
I took the plane up and down the runway a couple of times and did a couple of
runups with the cowl off. I seem to be a little down on power - (3950 instead of
4050 on static). When I got back the mount plate below the turbo had fresh oil
on it and I could see air bubbling through this oil at the joint of the mount
plate and the engine, just by the turbo. See attached picture with arrow. In
fact the entire join between the engine and the plate on the right (turbo) side
seems wet with oil and there's another pool at the front which I don't think
migrated from the back.
I get
the feeling that this "bubbling" might become a fine jet of oil which points
directly at the turbo when the engine's running, otherwise I don't see how
oil could get up into the turbo housing and smoke like it does. I'm trying
to understand why there might be pressure here. The breather is definitely not
blocked, and in fact, on this particular run, I'd even left the dipstick out.
Could the bubbling air be a compression leak from the join between the rotor
hosing and the backplate? My oil level is maybe 1/4 - 1/2 inch below the
level of the mount plate and the plane was on a slight grade making the back
lower. The bubbling stopped after a few minutes and did not return when we
turned the prop.
I'm
resigned to pulling the lower cowl, sump and sump plate and redoing the RTV join
(again), but I'm wondering - should there be pressure here? Is there some other
problem causing this. Am I overfull with oil? Could the turbo oil return
be "landing" on the mount plate, then running back along the join? I'm planning
a compression test next time I go down to the hangar.
Any
other thoughts or suggestions?
Regards,
John
(13.9 hrs and holding)
|