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OT Stainless steel for exhaust studs?

B

bruto

Stainless
Joined
Mar 14, 2008
Location
Benson, Vermont
Quick materials question. I have to replace the crossover pipe on my old Chevy truck. Of course the studs on the manifold were toast, and I've drilled them out, ready to thread, no sweat there. This time I'm not prepared to spring for the 12 dollar apiece Chevy studs I got last time, and plan to use either bolts or threaded rod (3/8 inch coarse). There's insufficient room on the top of the flange for bolt heads, so I expect to thread the studs into the manifold as usual. My simple question is whether there's any material reason not to use some stainless threaded rod I happen to have, rather than the mild steel normally used. Any reason stainless wouldn't be suitable for this application?
 
Many modern diesel engines use really nice bolts and studs on exhaust components. I overhaul B series Cummins engines regularly and find the exhaust manifold bolts and turbo studs come right out with hand tools after 20+ years and lots of miles. They do corrode, but just surface (400 series?) They are very strong too.

If you can tap or helicoil your manifolds to 10mm thread I'm certain you could find a really nice stud and nut combination from a pickup sized diesel engine that would suit your needs.
 
No reason at all that I can think of.
As a matter of fact, stainless exhaust studs are available as an aftermarket upgrade.
Been a while since I worked in an automotive shop but I remember when GM used to use brass studs in their exhaust manifolds.
 
I replaced the studs on my former truck with 316 stainless and and aluminum bronze nuts years later they still came apart easily. The key is to use stainless studs and bronze nuts. The first time I did this I used stainless nuts and they welded themselves solid to the studs after only a couple days of using the truck. Lesson learned . Stainless on stainless with heat is a recipy for trouble. I then had to make new studs and used aluminum bronze nuts and had great success
 
SS

Frederick Harvie said:
I replaced the studs on my former truck with 316 stainless and and aluminum bronze nuts years later they still came apart easily. The key is to use stainless studs and bronze nuts. The first time I did this I used stainless nuts and they welded themselves solid to the studs after only a couple days of using the truck. Lesson learned . Stainless on stainless with heat is a recipy for trouble. I then had to make new studs and used aluminum bronze nuts and had great success
Click to expand...

Ditto, Amen. You could even use plated nuts.
 
bruto said:
Quick materials question. I have to replace the crossover pipe on my old Chevy truck. Of course the studs on the manifold were toast, and I've drilled them out, ready to thread, no sweat there. This time I'm not prepared to spring for the 12 dollar apiece Chevy studs I got last time, and plan to use either bolts or threaded rod (3/8 inch coarse). There's insufficient room on the top of the flange for bolt heads, so I expect to thread the studs into the manifold as usual. My simple question is whether there's any material reason not to use some stainless threaded rod I happen to have, rather than the mild steel normally used. Any reason stainless wouldn't be suitable for this application?
Click to expand...

My Yanmar marine diesel came standard with s/steel manifold studs. The engine is over 20 years old and the studs are in perfect condition.

PDW
 
Most of they high heat stainless bolts are made from 330. It's good for over 1500F before it looses strength. Most of the hardening stainless like 416, 17-4, etc. are only rated to about 1100F before they loose strength.

If you're doing exhaust work, use nickel anti-seize instead of the copper.

We do stainless nuts on stainless studs all the time.
JR
 
The diesel mecanic that works on my VW diesels always uses
bronze nuts for the exhaust manifolds and turbos.
 
You could also do what they do in vacuum systems that are baked out. They coat the bolts with silver plating. Stops them from seizing up.
 
If I silver-plated the bolts on my 88 Chevy truck, it would probably double its value.

Thanks again to all for the interesting observations, even though some seem a bit exotic for getting the headpipes back on my old beater. Since I already had the stainless threaded rod, I've gone with that, cut pieces to size, ground 1/4 inch square ends on to facilitate screwing them in, and bought some brass nuts. Now all I need is for it to stop raining so I can get underneath it and finish the job.
 
For the exhaust studs on the race car I use stainless studs with copper nuts. I have never had a problem and no more snapping studs when you remove them.
 
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