Head bolts nightmare

[zukgod1]

Metal fatigue, I'd guess.

Dind ding ding!!

We have a winner..

Ya for what they cost it's just not worth it to not replace them. (try to say that 5 tims fast).

[Turbinepowered]

Why can't you reuse the old bolts if they're still in spec?  Nobody has been able to give me evidence why.

In the case of the stock 11mm headbolts, it's because spec sucks. The 11mm headbolts were barely adequate when brand new, which is part of why VW went to 12mm after the debut of the 1.6.

Technically, yes, you can reuse the 11mm stock headbolts. They are not torque-to-yield / stretch-type bolts, designed for a single use before replacement, but age and heat cycles by this point have likely begun to catch up to them, and there is no telling how long they will survive.

[vwt4]

All head bolts for every VW watercooled engine, diesel or otherwise, is a stretch bolt of some type and they should not be re-used.  The only thing I can think of that is happening is that either there is some crap on the threads in the block that is preventing proper torque, or there is oil filled up in the holes and by screwing down the bolt you are trying to compress it.    Either way, they shouldn't break that easily.

Brendan

Head bolts from 70's era engines are not stretch bolts, gas or diesel.

Why can't you reuse the old bolts if they're still in spec?  Nobody has been able to give me evidence why.

Because stretch bolts are one use.

Basically, when you torque them up, they literally stretch (torque to yield iirc)
and then once they are removed years down the line, they are already stretched so you cant get the correct torque on them again.

Higher torque is not always a tighter bolt/fixing....

so basically they are now past their best and need to go in the bin.
Having said that Ive re used them before on other cars and tweaked a little more torque in and they were ok...but those were hard times  :lol: