John,

I've chased oil leaks with fluorsescent dye you can buy at NAPA auto parts (or the Eastwood catalog and probably dozens of other places). It works great.

You clean your engine first. A degreaser spray can followed by a pressure washer does the trick. You dump the dye into your oil. Fire up the engine and run for a short period of time. The dye works under ultraviolet light so you've got to look at it under dim conditions. If the oil sprays out under pressure, follow the spraying tracks back to the source. If it leaks, follow the trail back up to where it originates.

The auto places will sell you an ultraviolet light kit but I bought my light at a local surplus outfit (American Science and Surplus) for maybe $8. The bottle of dye for oil costs $3 or so. They also sell dye for coolant, brake fluid, power steering, etc.

Barry Gardner
Wheaton, IL

John Slade wrote:

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)

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