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From: "Ron Laughlin" <ronlaughlin@gmail.com>
Subject: Re: [LML] Crankcase pressure=OIL ON BELLY
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References: <list-2937696@logan.com>

Hi Steve,
Could you post some pictures of your breather hose routing. Especially
the end of the breather tube/hose where it exits the cowl.

Ron Laughlin

On 5/25/08, Steve Colwell <mcmess1919@yahoo.com> wrote:
>
>
>
> My Cont. IO-550 (normally aspirated, stock comp ratio)  is blowing enough
> oil from the crankcase breather to put a thick coat on  =BD of the belly,
> halfway to the tail in 10 min. of flying.  Originally I thought I had
> overfilled the 8 qt. crankcase so I drained the oil, changed the filter a=
nd
> refilled with 6.5 qts.  During runup and takeoff roll the manometer (tapp=
ed
> into the crankcase vent about the mid-point of its length) will read zero
> until plane has about 120 knots indicated airspeed.  At 120 to 200 knots =
the
> manometer reads 4" to 5" with a short spike up to 14" to 20" when power i=
s
> reduced in the pattern.  The following tests have been run:
>
>
>
> Compression test:  high 60's to low 70's which I am told is normal for
> Continentals, oil is normal color (not black, which would indicate blow-b=
y)
>
>
>
> Washed engine with mineral spirits to see if any fresh oil was appearing.
>
>
>
> Upper plugs are normal color, maybe a dark tan insulator, no fouling
> problems
>
>
>
> Low pressure on crankcase with 12" balloon on crankcase vent:  takes abou=
t 3
> min to deflate, tried soap suds around all accessible seals, dipstick cap=
,
> mags, pushrod tubes, etc..
>
>
>
> Relocated crankcase vent to right side cowl outlet
>
>
>
> Cut a anti-siphon hole 6" above the end of the vent tube on normal left s=
ide
> exit.
>
>
>
> Taped the dipstick cap with aluminum tape.
>
>
>
> Put 20 psi air pressure on crankcase, soap suds again, air going past pis=
ton
> rings, tried turning prop with no noticeable difference from cyl to cyl.
>
>
>
> Replaced crankshaft seal.
>
>
>
> Anything that required a flight test would deposit the same thick coat of
> oil on the belly in a single trip around the pattern.   I have just about
> run out of ideas, the engine builder has never heard of anything like thi=
s
> and the cylinder supplier could only suggest it could be the crankshaft
> seal.   It could be a leaking seal in the alternators or mags or ????    =
I
> need help.
>
>
>
> Steve Colwell  Legacy   916 505-6099
>
>
>
>
>
>
>
>


--=20
Ron Laughlin