Stuck valve

I take it that it is stuck open.....

Might be work soaking it in a realeasing agent (diesel) for a while before you do anything.

If it is stuck open it could be gunk and toot building up on the valve stem.

Any attempt to get it to move needs to be done slowly and gently.

Martyn, I take it it's the one which is down (wide open) in the photo? If so, is the rocker on it because it's just resting there, or is the rocker jammed and holding the valve open? The rocker shaft looks corroded further along so if you haven't already it would be worth checking the rocker is free.

If you want to remove the valve and lap in properly it's a head off job, but it may be worth checking as Caddy says that it's not just gummed in with light rust & gunge. It doesn't take much to jam things very tightly. If you soak it for a while it will also do less damage when you do remove it.

If it's corroded in, which I assume to be the case, you'd also be looking for damage to the valve stem, guide and seat, or the rocker and shaft if the rocker's holding it down.

If it's bent because of a mechanical malady which has resulted in the valve hitting the piston due to a timing or some other failure you need to check the bottom end as well (piston, rod, big end, crank, timing gear)

Thanks all so far. Yes the one that is open is the stuck valve (centre of first photo). Rocker is free it is definitely the valve itself stuck. Will most likely soak it as suggested in diesel or something similar. Thanks all!

As a first thought I'd take the rocker shaft off, make sure piston is down, then hit the top of the valve stem with a mallet against the spring action ( gently ... )

The valve might snap back into place and be worth a try at running it. If it doesn't nothing much lost.

All sorted now i hope. Took the head off and reground it. See the Austin Gipsy restoration thread.

Thanks all for the help

Probably not relevant to this problem... but had a similar problem with a Land rover 2.25 engine - the valve was stuck open and I couldn't turn the engine by hand more than 1/2 a turn either way. Turns out the pushrod had come off the cam follower, so essentially was forcing the rocker up more than usual all the time. Solution was to reseat pushrod correctly in cam follower - although how it happened on a working engine is stil a mystery...

- although how it happened on a working engine is stil a mystery...

Valve bounce, weak spring, excessive valve tip clearance, etc.

Richard, sound advice, thanks.