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Oil leaking - any ideas?

I’ll have it checked tomorrow and will see ! Thanks for the hint

Safe landings !
EDLN, Germany

I have an oil drip from the O200 in the hangar. Suspected at vacuum pump, I’m getting it fixed by an engineer next week. Not noticeable oil loss, but noticeable on floor if the pan is not in the right position.
Oil leaks when engine running. Sticks on engine etc. Then drips off slowly over days. Probably microlitres, but it stains the floor.

Maoraigh
EGPE, United Kingdom

My view, worth what you are paying for it, and given that we have no engine builders posting here (they tend to shy away from social media at any cost ) is that if you have lots of oil p1ssing out with the engine stationary, the leak has to be outside the front of the oil seal.

On the plus side, for oil to be leaking from a crack, you would see the crack. Clean it up with avgas and watch.

Probably not easy with the prop screwed on, because you can’t get in there veru well. A narrow borescope may help.

Could it be leaking from the prop-crank interface? There is an o-ring seal there, IIRC

Administrator
Shoreham EGKA, United Kingdom

Hmm… yes, I can imagine that, as far as the prop mounting flange is considered. It would have to be either before or directly underneath the seal. That is possible.
But if it is in the inside part of the crankshaft behind the seal (the black part of your picture) – it wouldn’t leak through the seal, would it ?

Last Edited by EuroFlyer at 13 Feb 16:10
Safe landings !
EDLN, Germany

Clearly, it is impossible.

But if oil really keeps coming out after the engine has stopped, it could be you have a crack in the crankshaft end / the propeller mounting flange, and the fair quantity of oil which sits inside the crankshaft (this oil is normally used to pressurise the prop governor) could be leaking out for quite a while.

I wouldn’t want to run the engine like that, let alone fly with it.

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

How can you have a leak there on a stationary engine, when the oil should be way down in the sump?

That’s, even in wording, exactly the question I asked myself ^^

Safe landings !
EDLN, Germany

How can you have a leak there on a stationary engine, when the oil should be way down in the sump?

Administrator
Shoreham EGKA, United Kingdom

This is becoming pretty mysterious.

Established facts are so far:

  • The crankcase is not overpressured. The breather tube is free, and there is no oil residue coming out at the end; I assume there would be oil coming out if there’d be pressure in the case, no ?
  • Dip stick cap gasket is tight, all other gaskets as well,
  • Cylinders have been boroscoped, all have compression >60, are dry inside, no apparent issues with the piston rings,
  • Oil filter gasket is tight
  • Prop is a McCauley and the issue eddsPeter has mentioned doesn’t apply
  • Crankcase seal has been replaced three times now, last by a mechanic of the well renowned engine overhaul firm in Denmark
  • Leak is between the crankcase and top of crankshaft, and – mysteriously – even when the engine is not running.

According to the Danish firm, the crankshaft has been measured and was within limits. Well, obviously, it must have been, there is not radial play, only axial play.
It’s not so much oil that I cannot fly. The engine runs smoothly and all data are normal. Its just – annoying and, to an extent, nagging in the back of the head….

Maintenance guys, engine guys, myself, and all, have pretty much done everything imaginable and quite frankly, we’re at our wit’s end a bit…

So – ideas are appreciated ;)

Safe landings !
EDLN, Germany

See here.

Administrator
Shoreham EGKA, United Kingdom

For all, this is not the issue, as I have a McCauley prop.
Currently we’re checking if the crankcase may be overpressurized due to either a clogged breather tube or other sources.

Safe landings !
EDLN, Germany
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