hello yotatech. I'm a first time user and hoping for a some insight.
Wheels - 86 pickup with a 22re. Looooove this truck and want to drive it forever.
Problem - timing chain broke. No problem. Had the engine back together, BUT, then I found out it's an interference engine. It was running, however, really rough. I did a compression check and the results were #'s 1, 2, and 3 had excellent compression, #4 - 0 compression.
I've got the head off again and visually everything seems O.K. (I'm not too familiar with the inards of the head). Maybe the #4 valves are seized? The piston bores are smooth on inspection so I'm not suspecting ring damage.
Solution - my first thoughts are to buy a new (or remanufactured) head which looking into I can get for a good price. Should I be thinking of other damage somewhere? Could the rocker arms be out of whack?
Any help is much appreciated. Thanks to any who reply.

 

#4 valves probably got whacked, and bent. If they were to sieze the cyl would have compression theoretically, but the cam would have to break, or the valves would have to break. A remaned head sounds like the way to go. The other option would be to take the valves out, and replace em, and have all the machine work done.

You should check out the pistons and make sure they're ok, if they whacked #4 too hard it could have caused damage to the piston.

 

Thanks alex. Could you give me an idea of how to go about checking the piston. I'm assuming it has to be done internally. I've never worked on the block before. The top of the piston looks undamaged inspecting it just with the head off.

 

look for marks on the piston crown. Your valves will bend far before a piston or rod is damaged. Try spraying brake cleen into your intake ports and look for it to run out of the intake valves, this will indicate bent valves. Do the same for the exhaust side. Good luck!

 

Good tip Krazy. Before I buy brake clean, anything else to try that I might have in the garage before I go buy that?
Also to anyone who knows-my hanes manual states the rocker arms should have little play on the shafts(when the assembly is removed and inspecting) but the diagram is a little confusing. Mine rotate around the shaft 360 degrees. That's why I thought I might have rocker damage. A minor thought as I couldn't see how they should be wrecked. Just want to cover all my bases and why I mentioned it earlier. What should I expect to see for play on those? Thanks.

 

By the way the piston crowns all look the same and normal.

 

pistons are a visual inspection. if theyre damaged you'll know it from looking at them.

You could also try spraying something else down into the ports. Its more of a test to see if theres a gap between the valve, and the valve seat which would indicate bending. If theres no compression thats probably the issue, but try spraying something in through the intake/exhaust, and see it leaks down through the valve.

 

That's the plan today, I guess. Any thoughts or comments on the rocker assembly mentioned earlier?

 

not sure about the rocker arm shaft assy., but if the rockers were riding the cam properly on the one end, and the valve stems on the other end than that shouldn't be the reason for loss of compression.