#1 cylinder leakage

C

Clifford

Active Member
Annual time. 500 hrsTTSN. Number 1 cylinder has been running 70/80 or 72/80 for the last 2 years. All other cylinders run 78/80 - 79/80/ Number 1 cylinder also always runs hot. This annual I noticed blow-by leakage coming out the exhaust while checking #1 cylinder.

I've had suspicions about #1 for quite some time; mostly blaming the induction system for uneven distribution. But now I'm narrowing it down to lower compression and leakage for that cylinder. Earlier this year I pulled the rocker arms and checked the lifters on #1 cylinder; and they checked out per the Lycoming manual.

So I'm hoping some engine gurus here can steer me as to what to do next. Is there a stop-gap measure short of rebuilt or new cylinders? Any recommendations??
Thanks a ton,
 
Snowbirdxx

Snowbirdxx

Well-Known Member
If you have blowby coming from the exhaust ITS the exhaust valve. Fly with some valve cleaning additive for 3 HRS and Check compression again
If IT did Not Help, valveseat needs lapping. Maybe the valve Guides are worn.
 
Snowbirdxx

Snowbirdxx

Well-Known Member
When checking the intake system for leaks, there is an easy method. Remove cowls, start engine , let it idle and spray engine starter spray on the questioned parts Joints. If RPM goes up, there is the leak.
If you disassemble the intake, check the flanges / studs on the oilpan, they may be loose.. Replace the rubber hoses with ones from Superior. They will not swell up when cargas is used. . Flanges on the cylinders must be slightly preloaded to be convex, to be able to seal with the thin gasket. Even here are the Superior gaskets better,
 
F

flyingjack

Active Member
Gust Kalatzes said:
I'm not a guru but wouldn't #1 cylinder typically be the coolest running cylinder? Could there be an intake leak causing the heat and finally burning the exhaust valve?

Just a thought.
Click to expand...
Gust, I do believe you're in the top 1% of "gurus" on this forum. Thank you for all your input.
 
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