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Broken head bolt


ltd999

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Hey,

 

I am in the process of replacing the head gasket on my 120y, but when I torqued up the bolts, one broke :(

 

I was lucky enough to remove it ok. But not sure if I can use the same head gasket? It's obviously new but since it has half torqued up I had to pull the head off again. Is it ok to just clean the gasket with a rag and reuse it or do I need another one?

 

Also I think the bolt broke either because my k.c. tools torque wrench didn't click or the bolt holes werent clean properly. I oiled them before going in, and between the washer surfaces. Though they were the old bolts, maybe this was the problem..

 

Thanks for your help

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You need to chase the threads in all the head bolt holes.  There is a special tap for this, it does not remove as much metal as a normal thread cutting tap.  After chasing the threads, you need to blow all the debris out of the hole, then clean the hole with solvent.  Blow the hole out with air again, allow it to dry.   Then you can install the head.

You did check the block and head for flatness, and cleaned both the mating surfaces on the head, and the block?

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Hey Daniel. Yeah I guess I didn't clean the holes enough. I used a normal head bolt, some rags, brake cleaner and a straw to blow it all haha. I have read of cutting a couple of lines in a head bolt and using that to clean the thread?

 

I didn't check the block, but the head was skimmed. I honestly can't see the block warped but will check anyway.

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A dirty hole wouldn't break a bolt, it would just reach the torque value too soon and not be holding the head properly. I've scored a head bolt down the threads with an angle grinder and used it as a tap. Rub some thick grease on it first to collect any debris. 

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