# 86 300ZX Head Bolt Failed



## ReggieT (Apr 25, 2005)

Greetings:
I've got an 86 300ZX in the garage with the engine partially disassembled. A head bolt broke while driving, lodged between a cam lobe and the right cylinder head which caused the cam sprocket to shear off the end of the camshaft. Not sure of all the damage it caused yet (head, valves pistons...). Has anyone heard of the issue before? I understand a TSB was issued 86/87 for dealers to replace the head bolts with higher grade bolts but that didn't do the owners any good until it was too late... (I wish I had known when I replaced the timing belt a few years before)


Thoughts ??


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## Zen31ZR (Mar 24, 2004)

Headbolts might have been reused more than twice. After that they can be stretched too far and break. Never heard of that happening before, doesn't mean it hasn't happened, though.

You'll probably need to replace the entire head, there may be internal damage as well that you won't see.


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