I was removing the head on my mom's 968. Each of the 10 head nuts turned about 1/8 to 1/4 of a turn before actually cracking loose. When they did crack, it was a loud crack! Anyway I thought that the initial turning, before the cracking, was me twisting the studs. Is there a way to find out for sure? Should I replace the studs?

 

That cracking sound is normal. I had the same thing happen on my 944. The studs are stuck with red loctite from the factory and can not be removed without using a map torch. I doubt the stud came loose, but you can check after you get the head off. Those guys at Devek told me it is unnecessary to replace the studs when I had the head reassembled.

 

You could've shot some penetrating fluid in there to help the loosening procedure. It also helps to tap the bolt sharply w/ a hammer before loosening as well.

Just FFR...

 

Those studs are long- it wouldn't surprise me if they did some twisting when breaking the nut loose. Torsional loading within the material's elastic limit is O.K. (that's how our torsion bar rear suspension works). If you are really concerned have them magnafluxed or zygloed to look for cracks.

 

There are a few rules of thumb when working on cars:

1 - When you're removing something that's NOT easy to get to, always replace the gasket, it's good insurance.

2 - ALWAYS replace head bolts or studs when you're removing the cyl head. It's not as crucial on main caps, but it is on the cyl head which goes through many many severe heat cycles. The only bolts or studs that I would feel safe re-using are ARP. It's much better to spend $100 bucks now, than another $500 later.


Todd,
2006 Pontiac Solstice
2004 VW Beetle Convertible (Wife's)
2002 Ford Crown Victoria LX-P74
1987 Pontiac Fiero SE / V6
1984 Porsche 944
1981 Pontiac Trans Am WS6
1973 Volkswagen Type-2 Transporter

 

Several recent threads in the turbo forum had many people saying there is nothing wrong with reusing the stock studs, even multiple times. And these were people doing high-boost situations, like lart.

 

Although I haven't done it, removing the studs does not sound like something for the inexperienced. You apparently have to locally cook the aluinum block where the stud screws in because of the super-loctite used. You don't want to overheat the aluminum.... Although studs do stretch when you torque everything down, they stretch within the elastic limit of the material which means not permanently stretched.

 

I apologize, in the title I meant to say "did I twist my head studs" not "stretch".

I know studs can be reused several times if unabused, but my concern is because the engine is high-mileage (220,000 miles) and the head had never been removed before. While removing the head nuts it felt like the studs twisted 1/8 to 1/4 of a turn before the nuts cracked loose. I was wondering if this amount of twist is beyond the elastic limit of torsion for the studs.

I usually don't mind just dropping the extra dough for the new parts for peace of mind... but I have already done that in quite a few places on this job. I've already dropped about $300 on parts, $200 on 'just-in-case' stuff, and another $200 is about to go into machining services. I'm approaching the shop charge of $1000 for a headgasket job, and I'm scraping my own knuckles.

 

Penetrating fluid? On head nuts, which are always submerged in motor oil? I thought it wouldn't help / do anything.

 

FWIW, removing the head studs on my block was *THE* most labor intensive part of my rebuild.

Heat and more heat, pliers from hell, wedge the block against something solid and use all my strength to get a quarter turn..wow

The amount of loctite that the kind gentlemen from Stuttgart (hehe stud garden) used to hold those studs in the block was a bit over the top - to say the least.

Based on my limited but first hand knowledge, I really doubt you twisted those studs in the block, or enough to damage them.