I was getting ready to pull the engine out of a 65 series Chevy truck for a hot rod project. I drove the truck home a couple of miles. It didn't overheat and oil pressure was over 50 psi. It had a miss in it but since it hadn't been in service for years I pulled the plugs for a compression test. I found the #5 cylinder exhaust valve pushed all the way open and stuck there. I pulled the rocker arm off and tapped on the valve thinking it was just stuck open, the spring did not look broken. It did not try to return open at all, it just went down to coil bind, I was able to pry it up only a little but not back where it should be. The pushrod was not bent but was high and it did not tap down easy either. The lifter was pushed up and it would not go down or even try to follow the cam. I've never seen or heard of this. Anybody have any ideas what I can expect when I pull it apart?
Yep. Seen one before, it was a tall deck too. Had a skip, after checking things out, pulled a valve cover, first thing I saw was a valve in the open position that shouldn't have been. Thought it was a guide issue at first.
Sounds like the valve stuck open and the piston clinched it over like a nail. Might have broken the valve guide and possibly cracked the head. I hate to think what happened to the piston. Might have even scrubbed the cam & lifter flat too. Check everything. Outside of that, you should be good to go. Sorry.
Likely old stale gas or something caused the valve to sieze in the guide. and without the valve spring pressure to keep it riding on the cam the lifter bounced up above its normal travel and the varnish on the lifter near its base caused to stick also. Tap that lifter back down. Get a propane torch and heat on the valve guide and stem while squirting it with penetrating oil and it might come loose. Of course you will take the tension out of the valve spring. However its possible to change the spring without pulling the head.
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