912 ULS Oil Leak

by Ron Greene in 912 / 914 Technical Questions 9 years ago

912ULS 696 hours. Noticed a drop of oil on the floor near the oil breather hose. Took cowl off and followed the oil, wasn't from the hose, looks to be coming from either the #1 or #3 cylinder head to cylinder junction. Anyone ever have this problem. Looks like the only seal at that point is the O-rings on the cylinder studs. Could this be the problem. Any suggestions?

Thanks,
Ron

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Re: 912 ULS Oil Leak

by Roger Lee » 9 years ago

Roger Lee

127 5.2k 4.78k

Hi Ron,

Small oil drips and leaks can be deceiving.
I would clean everything up and run it and take another look before you work on anything. too many people rip into things only to find it wasn't the real problem and something like oil was blown by air to another location away from the original problem. If it's only a drip it most likely isn't an immediate flight issue.
I always check the bottom of the oil tank, the oil tank vent hose, the bottom of the oil filter, the bottom of the engine where the large banjo bolt is mounted for the oil return and then any hose clamp for the oil hose for the area of concern.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Re: 912 ULS Oil Leak

by Ron Greene » 9 years ago

Ron Greene

5 30 0

Thanks roger. I will clean it up and try another run to see if it can be determined where the leak is. It was really more like 2 square inches of oil on the floor and more on the lower water hoses where it ran to the low point then dripped.
Ron

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Re: 912 ULS Oil Leak

by Przemysław Wiśniewski » 9 years ago

Przemysław Wiśniewski

65 247 3

Frequent is leak from hydraulic tappets covers (where cover meet head) or valve cover gasket.

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Re: 912 ULS Oil Leak

by Ron Greene » 9 years ago

Ron Greene

5 30 0

Yesterday I cleaned the engine, ran it for 20 minutes on the ground and looked for the leak. Leak is coming from #3 cylinder at the cylinder head/cylinder junction at the bottom center. Looking at the cylinder head/cylinder junction on the sides and top it is dry.

Cleaned the engine again, re-torqued #3 cylinder head and ran it for 20 minutes on the ground and could not see a leak. Let it sit overnight and still could not see a leak.

This morning put the cowl on the engine and flew for thirty minutes, took the cowl off and it is leaking from the same place. Probably the equivalent of 15-20 drops of oil, hard to say exactly.

I do not understand why there would be oil at this location in the first place. below the valves and above the rings, any ideas? Checked the lower plug out of curiosity, perfect.

Head temps average 190-210 degrees F., no overheat issues.

Any ideas?
Thanks

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Re: 912 ULS Oil Leak

by Ron Greene » 9 years ago

Ron Greene

5 30 0

Just found SI 912-019, it does not apply by serial number. Mine is 4427595 with original crankcase. Could a bad stud O-ring at the case allow oil to travel up the stud and leak at the cylinder head/cylinder junction?
Thanks

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912 ULS Oil Leak

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