Exhaust Manifold Stud Installation

[Larry M.]

I'm ready to install new stainless steel studs into the flange of my stock cast iron exhaust manifolds.

Are there any recommendations or pros/cons to using some sort of Loctite on the threads that go into the flange?

Thanks,
Larry

[Jimmy G.]

Re: Exhaust Manifold Stud Installation

Loctite (an organically derived material) will not typically withstand the heat of a manifold Put them in, snug them to the correct torque specs and they should be good. You can also disfigure one thread near the end so the fit will be tight but that is probably not needed

[Timothy B.]

Re: Exhaust Manifold Stud Installation

I would double nut them and install snug, run a 3/8 tap inside first to clean the threads. When I ordered the reproduction stock type nuts they were crimped so tight I ran the tap through them to round them more because the interference fit was so tight.

[Joe L.]

Re: Exhaust Manifold Stud Installation

I'm ready to install new stainless steel studs into the flange of my stock cast iron exhaust manifolds.

Are there any recommendations or pros/cons to using some sort of Loctite on the threads that go into the flange?

Thanks,
Larry

Larry------


A lot of the loosening of these studs/nuts is due to progressive compression of the stock-type packing ("do-nut" gaskets). I don't use the stock-type packing. Instead use the sintered iron variety. They're GM-discontinued but they're available from NAPA and others. The NAPA part numbers are as follows:

2"----------EXH 31416

2-1/2"-----EXH 31508

[Patrick H.]

Re: Exhaust Manifold Stud Installation

I run a thread restorer (like a tap, but it isn't) through the holes ahead of time. You can then install the studs and life will be good.

[Larry M.]

Re: Exhaust Manifold Stud Installation

Jim, Tim, Joe, Pat -


Thanks for your responses. I knew that no sealer was originally used, but wasn't aware if that remained the current preferred method; or whether time had produced a new-and-improved process. I'll install as prescribed.

Joe, thanks for the gasket tip; I'll pick up a pair.

Larry

[Patrick B.]

Re: Exhaust Manifold Stud Installation

I would put anti-seize on them even if they are stainless and use brass nuts too. Retighten the nuts after a few hundred miles.

[Larry M.]

Re: Exhaust Manifold Stud Installation

Pat -

I've got the brass nuts; hadn't thought of the anti-sieze, but will use it. Thanks!

Larry

[Patrick H.]

Re: Exhaust Manifold Stud Installation

I've used anti-seize along with the repro correct shape nuts and had good success. That way you can keep the original appearance and not worry about removing them someday.

http://www.parts123.com/corvettecentral/dyndetail.pta?catalog=0000050g&ukey=22334

[Joe L.]

Re: Exhaust Manifold Stud Installation

Pat -

I've got the brass nuts; hadn't thought of the anti-sieze, but will use it. Thanks!

Larry

Larry-------


I ALWAYS use anti-seize on these studs. ALWAYS. I recommend high temperature, nickel-based anti-seize. In fact, I use this exclusively whenever I use anti-seize.


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[Tom P.]

Re: Exhaust Manifold Stud Installation

Also, I would REALLY discourage using stainless nuts on stainless studs/bolts. If stainless studs are installed, then I would recommend using carbon steel (zinc plated) nuts. The threads of stainless nuts on stainless studs/bolts will very frequently have a tendency to gall and then become seized. When that happens your only option (when trying to remove the nuts) is to turn them with enough torque to break the bolt. Yes, you can use anti-seize on stainless nuts/bolts, but over a period of time, that may not prevent stainless from galling and seizing. Now, if a stainless bolt is used for applications such as intake, exhaust manifolds, bell housings, water pumps, etc, the stainless is going into cast iron (or alum) and I've NEVER seen a stainless bolt seize in alum or iron.

[Dan D.]

Re: Exhaust Manifold Stud Installation

Tom is right. Stainless on stainless is a bad combination. You are inviting galling, and I can tell you when this happens it is all but impossible to remove the nut. The more you turn it the worse it galls, and very quickly to the point where breaking the bolt is the only option. And reversing the direction only makes it worse - not better. Stainless is a very tough metal and it takes a lot of force to break it.

-Dan-

[Joe L.]

Re: Exhaust Manifold Stud Installation

Tom is right. Stainless on stainless is a bad combination. You are inviting galling, and I can tell you when this happens it is all but impossible to remove the nut. The more you turn it the worse it galls, and very quickly to the point where breaking the bolt is the only option. And reversing the direction only makes it worse - not better. Stainless is a very tough metal and it takes a lot of force to break it.

-Dan-

Dan------


I always use brass nuts on the exhaust studs. However, I think the original style, steel locking nuts would work OK. I never use stainless nuts on the exhaust studs.

[Larry M.]

Re: Exhaust Manifold Stud Installation

Larry-------


I ALWAYS use anti-seize on these studs. ALWAYS. I recommend high temperature, nickel-based anti-seize. In fact, I use this exclusively whenever I use anti-seize.


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Joe, thanks; I appreciate the recommendation.

[Larry M.]

Re: Exhaust Manifold Stud Installation

you can keep the original appearance and not worry about removing them someday.

Pat, thanks for the caution, but the car has more noticeable non-original appearing items to keep a potential judge busy.
Larry