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oh no.... stupid bolt

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me agian, as i tryed to take off one of the thromostat bolts, one broke. It left me with none of the bolt sticking out. Oh man i couldnt beleive it, i need some help whether to use a screw extractor or use a tap and die. I love my 1973 240z but it dont love me... so sad, well i wont give up. Please any info. will help. Thank u

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  • 2 weeks later...

Is the bolt sticking out enough so you can grab it

with vice-grips? Be careful with that head, it's

aluminum. Your bolt is steel. It's really easy to over-

tighten and really mess up the threads.

You might want to try and drill out the bolt with a

smaller bit. Then, you'll have enough room to insert

the extractor.



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  • 3 months later...

I'm in the process of doing this right now on an exhaust stud. So far I've broken 2 of them. I did the thermostat housing about 7 years ago. Yes, I've been down this road before.

If the bolt is broken off flush with the head, the only way to get it out is to drill. Take a center punch or a sharp metal punch and put a "dent" in the bolt as close to center as you can. Start drilling with a small diameter bit first, like 1/16" or 1/8". That way you can correct your center mark somewhat. Once your hole is drilled in the center then you can step up to a larger bit. Step the bit size in increments, though. It really makes it easier.

The hole and thread size of the thermostat housing, exhaust, and intake manifold studs are designated as M8 x 1.25. This is a metric designation. You will need a tap this size and a metric drill bit of 6.8 mm. This is roughly 1/4", but don't use a 1/4" bit. It is too small and you won't be able to tap the threads.

Go slow and use a little cutting fluid or light weight oil when tapping, it'll help. Above all, be patient and thorough. Good luck.


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if it is sticking out even a little bit you can take a hacksaw and cut a slice in it .. or two then get in there with a screwdriver that fits the slice perfect(you have one shot at this) pray and unscrew.. dont know if itll work in your tough situation but it has worked for me in easier places.. wanna buy a P79 head?

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Is it safe to use teflon tape on your Z? I could see how it might not be safe on critical elements of the car. Sure, it works on plumbing, but, is it safe to use it on a flywheel bolt or something critical like that? A header might be a different story because it's not moving a hundred miles an hour. But, I'm just wondering about the safety of teflon tape used in these situations...

Any ideas?

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Mike,I don't know about flywheel bolts.The reason I use teflon tape on thermo bolt is that a steel bolt and aluminmum hole cause a chemical reaction that is similiar to welding.This is due to dissimiliar metals.The teflon acts as an insulator.I'm not sure why the thermo housing is the worst,maybe the extra hot and cool of the collant adds to the problem.It seems a Z car right of passage.Everyone fights that demon at least once.Along with vapor lock,dim lights at idle and exhaust smell getting into the car when you let off the gas.All common demons to overcome.

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I would not use Teflon tape on any exhaust studs. I have seen teflon tape degrade to next to nothing on a coolant testing apparatus at 450 degrees F. Exhaust temperatures are much higher. The best thing to do (and what I'm doing now) is to remove all the studs you can, clean up all threads (on the stud and in the head), then put them back using anti-seize.

IMO, this is much better than using teflon tape. Other thing is, if you don't wrap the tape on the threads in the right direction, then they just unwrap as you put the stud or bolt in. Then it does you no good. More hassle than it's worth.


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anti sieze is unreal.. i love it.. teflon tape? seems like im always cursing that stuff.. i guess for plumbings cool but for a car?i never even thought of using that. it makes fixing my compressor a pain too.. i didnt think it responded well to heat.. maybe it does though..i put anti sieze on everyhting! even my hands.. then it gets on everything you touch. my toolbox is almost all silver now.. jk

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