Cylinder head broken off at manifold stud.

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Cylinder head broken off at manifold stud.

Postby mickeyfinn » Tue Jul 05, 2022 6:25 pm

I’m replacing my stock ST165 exhaust manifold with as ST185 manifold to accommodate a KO Racing Street Brawler turbo setup.
I pulled all the manifold studs, chased the threads, and installed new studs, with the exception of one stud that broke off as I tried to remove it.
I drilled the stud out, and tried to remove it with a bolt extractor. This bolt extractor is a tapered kind that screws deeper into the hole as you turn it to unscrew the stud.
Unfortunately, so much pressure built up that it broke the stud boss right off the cylinder head!
I need my ass kicked for not seeing the drawback of this tool and should have went with a square type.

Regardless, I’m hating life now.
Here is a picture of the broken boss.

Broken Boss.jpg


Has anyone experienced anything like this?

I called a very good local mechanic and he said he just repaired a 3SGTE head out of an MR2 Turbo a couple weeks ago. The same hole broke on it. He was able to successfully build up weld and tap and Heli-Coil a new hole. But the head had to be removed.

Just sharing my story for pity, ridicule, or just warning others what not to do…
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Re: Cylinder head broken off at manifold stud.

Postby Roreri » Wed Jul 06, 2022 6:01 pm

Ooof! That’s a shitty turn for sure. Thanks for sharing the cautionary tale and sorry that happened to you.

On the plus side it looks like a fine opportunity to redo/upgrade the head gasket and do any other any other head off work. Would it be easier to source a new head?
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1992 Toyota Celica

Re: Cylinder head broken off at manifold stud.

Postby simple » Wed Jul 06, 2022 6:58 pm

If you need a used ST165 cylinder head let me know. I've got one. There was one on Ebay for a while but I think it finally sold.
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