noahcount

On my 97' SOHC I have the timing belt off( it jumped a couple of teeth while trying to start the car ), and am trying to turn the camshaft at the sprocket ( after making sure all the pistons are down far enough in their cylinders to avoid contact with valves). Very difficult to do, so I back out all the valve adjustment screws as far as they will go, and notice that the rockers on several valves are solidly wedged, no slack.
I'm thinking valve damage on those tight valves, but before I yank the head, wanted to get some opinions. Does this sound like toasted valves or am I missing something? Is there some other way to check for damage short of pulling the head? Thanks.

Former User

If the cam won't turn freely, then it's time to remove the head and inspect the valves and pistons.

apexi_rsx

leakdown test with the cam out so all the valves are shut could help diagnosis this. some times running a straight edge along the top of the valves with the cam out can show if they are bent as well. if one is short of the straight edge its probably bent it doesn't take much to loose compression.

noahcount

Ron: I was afraid of that.

Apexi rsx: Interesting test, but wouldn't my backing out the rocker adjustment screws to their limits accomplish the same thing? With the screws backed out, if the valves aren't bent then the rocker arms should be free to move( as long as the pistons aren't in the way, which they are not ) I would think. I'm going to try your straight edge idea anyway.

noahcount

Are you sure about that? Looking at things closer I don't see how the cam should freely turn against valve spring pressure since there appears to always be a lobe in contact with a rocker somewhere along the line.

Former User

If you install the timing belt with the cam and crank synchronized at TDC1 and remove the spark plugs, then the cam should turn freely with the crank. If not, there's a problem.

noahcount

Yea, a little miscommunication there, in the OP I said I was turning it at the camshaft sprocket. I should have figured that one out myself, doh.