New head bolts, rebuilt head. That last 1/4 turn always feels like it's going to snap the new OEM head bolt. Torque hits around 98 or so typically. Just wonder at what point they snap.
At what torque will a new head bolt break
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I don't know the answer to your question.
I do know one really, really felt as if it was about to snap at the last turn.
I figure, with no education or information to speak of, that the oem head bolt will not snap or twist up without much more torque than we go to.
i hope
I do know one really, really felt as if it was about to snap at the last turn.
I figure, with no education or information to speak of, that the oem head bolt will not snap or twist up without much more torque than we go to.
i hope
To bad i just got rid of an old block. I have some new oem head bolts i coulda run in till it popped.
I'm always more worried they will strip rather than snap. If they snap off I can put a new one in, if they strip the block threads its a whole new fight.
I've never stripped or snapped one though....
I've never stripped or snapped one though....
I got the same uneasy feeling on several of my head bolts on that last quarter turn. Glad to know I'm not the only one.
My limited experience is that they don't snap off immediately but instead stretch out in a way that causes torque to drop before the bolts break. I've had this happen with a few bolts on the 1FZ including original head bolts that I tried to reuse per the FSM but then replaced after they wouldn't torque up. I also had this happen on the oil cooler bolts. In both cases I was using a torque wrench and at least trying to follow the FSM assembly procedure though I was reusing old bolts that I assumed had never been removed/replaced..
What happened in my cases were that while torquing the bolts the torque/resistance initially ramped up as expected but just before peak resistance the torque either hit a plateau or suddenly fell off and felt much lighter. I then stopped tightening and pulled the bolts and they had a pinched in section where the bolt stretched. The pinched in section was noticeably smaller diameter all the way around the bolt. This was more pronounced for the smaller bolts, perhaps because they are quicker to damage if they are tightened after they fail. If you keep trying to torque the bolt it will keep stretching until it snaps off and then you can typically easily remove the remaining broken off stud if you can get to it but it should be easy to stop torquing and remove the bolt before it breaks.
What happened in my cases were that while torquing the bolts the torque/resistance initially ramped up as expected but just before peak resistance the torque either hit a plateau or suddenly fell off and felt much lighter. I then stopped tightening and pulled the bolts and they had a pinched in section where the bolt stretched. The pinched in section was noticeably smaller diameter all the way around the bolt. This was more pronounced for the smaller bolts, perhaps because they are quicker to damage if they are tightened after they fail. If you keep trying to torque the bolt it will keep stretching until it snaps off and then you can typically easily remove the remaining broken off stud if you can get to it but it should be easy to stop torquing and remove the bolt before it breaks.
Last edited:
mehbohdi
SILVER Star
Having had to helicoil a block in the past, I'm of the opinion that new bolts are just a part of doing any head R&R on any modern vehicle. Bolts are not that expensive and it will give you less to think about. Modern engines are all about using every amount of usable space, the most efficient way possible. Which means they use the smallest most effective material for the application and not much more. Which is commendable, to a engineering stand point. Unlike the good old days when things were bigger is better and materials were not overly stressed, in stock form. Toyota is the exception and did it's very best on a typical 2JZ which is still IMO 1 of the best inline 6 engines available. When a automotive company was run by engineers not bean counters. I'll shut up now....
