replace head nuts?

nynor · 12-13-2004, 06:04 AM

i read somewhere that if the cylinder head is removed, the nuts have to be replaced... is this true?

adrian jaye · 12-13-2004, 06:37 AM

you dont "have to"

but it's a good suggestion to do so.

A mechanic I know swears by it

nynor · 12-13-2004, 06:39 AM

what kinds of problems am i risking if i don't replace the nuts?

Zero10 · 12-13-2004, 07:40 AM

They may have been fatigued, or stressed on their previous installation, or any time afterwards. I've hardly ever seen them fail, but yet a lot of people swear by replacing them. Worst case, one of the nuts will split or strip, perhaps destroying a stud in the process, and you'll have a head gasket failure.

ae1969 · 12-13-2004, 07:56 AM

The least I replace are the nuts and washers. In an ideal world you are supposed to replace the studs as well.........but if the studs look good (no corrosion) then its fine.

I haven't heard of a nut failing on these cars. More than likely you will pull one of the studs if something were to fail. The studs are actually meant to stretch and are meant to be a single use.........

You want the threads to be nice and clean...........so a nice new nut will give you the most accurate torque reading IMO.

nynor · 12-13-2004, 09:06 AM

ok, thanks. calling the dealership now. if they don't have them, i'll order from pelican

bryanthompson · bryanthompson's Garage

I thought it had to do with stretching of the studs... So when you torque it down, it won't be the correct torque. Not sure, tho.

Granite 944 · 12-13-2004, 02:11 PM

These head studs used on these engines are not considered a one shot, "torque to yeild" bolt, are they? If they were, I would think it would really specify that in the FSM, where I've never seen mention of it, however I may have missed it.
A torque to yeild bolt you truly don't ever want to use more than once. The nuts/washers, I wouldn't think it would be a problem to reuse, providing that they don't have any big burrs or qouges on the mating surfaces that can not be lightly sanded off, since that would affect the ability to torque them properly.
No expert here, just thoughts and questions.

If all of this is being done do to a compete engine rebuild, I'd replace all head studs/nuts, just as part of the process and insurance value of it.

nynor · 12-13-2004, 07:51 PM

well, i read the shop manual, and haynes, and the only thing it said was to make sure that the parts are lightly oiled with motor oil and make sure the washers don't spin with the nut. further, those are some STOUT parts... the nuts are machine grade 10, for crying out loud.

mike944 · 12-14-2004, 05:55 AM

I've never replaced the nuts or the studs. The studs are definitely not torque-to-yield studs. It's never a bad idea to replace things like that, but not really necessary.

Just inspect the threads, washers & nuts to check for any booger'ed up threads (a highly technical term) and gouged up faces of the nut and washer. If things are galled up and such, torque readings will be off, and head torque is pretty important.

Oil them just like the manual specifies, and make sure the faces between the washer and the head casting are clean and not lubricated, the washer is not supposed to turn on the head. (As an Engineer I can't figure out what difference that would really make, but i'm not going to try to second-guess the people who designed this engine)

adrian jaye · 12-14-2004, 06:57 AM

my analyst suggested there was something wrong with my head nuts

but 5 years of therapy and 10,000 bucks later I feel fine !!!!!!!!