Would an overheated engine cause a valve to become stuck or frozen? I have a 91 toyota 4x4 22-re engine. The radiator failed, and it overheated on the freeway. I had it towed home, let it cool, then started it up. It sounds like there is valve lash coming from the #4 cylinder. A loud click, like a BB is inside there. (It's not the timing chain guides) There we no valve lash sound of anykind before the overheat. I pulled the head to take a look. So now that I have the head off, what should I look for? Would an overheat cause that?

Yes, over heating can cause problems with the head. Valve seats can fall out. Valve guides can fall out. Did you do a compression test before removing the head? Did you try adjusting the valves? Was the valve cover gasket new? If you reused an old one, it may have been compressed and the rocker(s) will hit the valve cover. Do a leak down test on the bore and on the head. A black and sooty spark plug means either the cylinder is not burning correctly or there is too much oil getting into the combustion chamber. Did you try a different spark plug wire on cylinder #4? Continuity may be good, but it may not be able to handle the voltage. Before pulling the head, did you turn the motor by hand and watch the valves open and close? Look around the edges of the bore to see if there is any debri (broken ring). Look for holes in the piston.

I did a valve check before I pulled the head, and the valve clearance appeared to be fine. I'll put the head back on and turn it by hand to see if the valves move up and down. I don't see anything significant as far as holes or debris in the bore. I have a feeling a valve is stuck closed. The #4 piston head was quite oily as first glance. The other pistions were dry.

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