Oil on top

by Sam Purpura in General Tech Discussion 6 years ago

On a 914 oil is collecting at the base of #3 and #4 cylinders on the top of the engine and appeared to be leaking the Evans coolant as it seemed to emanate from under the expansion tank but it’s not leaking coolant.
I’ve cleaned the area and found no cracks in the crankcase. Any similar experiences?

Re: Oil on top

by Alan Arnold » 6 years ago

Alan Arnold

20 188 145

I've an oil leak that is coming from the #2 cylinder base gasket and working its way to the top seam of the case. Air flow, you know. I've also a mystery coolant leak that I've, maybe, traced to the oil and coolant return fixture on the back side of the engine. My 2006 engine has 800hrs and is almost to the 12 year TBO. According to a Lockwood technician, the seals are the reason for the 12 year limit. Since a Lycombing engine leaks more when new than my Rotax is leaking now, there's no way I'm spending that much for an overhaul; I'll just replace gaskets and o-rings "on condition". The first sign of this was the o-rings on the coolant fittings beside the intake manifolds. Have fun. That's what I'm doing.

Alan

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Re: Oil on top

by Sam Purpura » 6 years ago

Sam Purpura

11 190 999

That leak was located. There was a hairline crack in the crankcase on top near the #3 cylinder approximately 1.25” long. It is not visible to the naked eye but oil bubbles through when pressurized. The crack is about 1/8” below the red Sharpie mark.

1B31B939-2943-4E32-BB0D-6E163BD15959.jpeg (You do not have access to download this file.)

932D4705-6AB8-47F9-8EAB-3056A4602E5B.jpeg (You do not have access to download this file.)

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Re: Oil on top

by Roger Lee » 6 years ago

Roger Lee

126 5.14k 4.62k

Hi Sam,
One common cause for a cracked case on top.........This type of crack used to show up with the older crankcase and people over pitching the prop that over stressed the engine. People who get under 5500 rpm WOT in flat and level flight aren't doing themselves any favors. If you have an engine that is approximately mid 2006 and earlier (1500 hr. TBO) then you have this case. Don't over pitch your props. There are NO redeeming qualities with an over pitched prop.

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

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