Exhaust valve stuck

[Everett Taylor]

Hello all,

While troubleshooting to get the A4 in my Pearson 300 started, I found I have zero compression in #3 cylinder. The other cylinders are at 70+psi. I can just barely see the exhaust valve in $3 and it is open - it does not move when turning the engine over. I've squirted Marvel Mystery oil in it's direction but to no effect. Is there a proven safe method for freeing a sticky valve?

Thanks for the assist,
Everett

[Don Moyer]

Everett,

Some folks are successful in inserting a smallish Allen wrench or bent screwdriver in through the spark plug hole, but it is frequently necessary to remove the head to free a stuck exhaust valve.

Don

[Everett Taylor]

Thanks Don,

Maybe I'll get lucky if I make the tool right- Is it best to press down on the valve, tap it on the side or try prying it up & down? All of the above?

Everett

[Don Moyer]

Everett,

You'll have to press down on the top of the valve.

I suggest using a cheap screwdriver, and bend it on location a little bit at a time so that you can "snake" it down through the spark plug hole between the top of the valve and the roof of the combustion chamber. Expensive screwdrivers are usually a bit on the hard side, and they tend to break before they bend.

Don

[Everett Taylor]

Don,

A thorough spraying with carb cleaner & the right sized Allen wrench on top of the valve -tapped with a hammer-did the job. I rotated the engine and repeated until the valve dropped by itself. The compression was low-about 45psi. After changing the oil I started the engine and the valve settled in. Lucky. Thanks for the assist.

Everett

[Don Moyer]

Everett,

Congratulations on a job well done!

Don