Correct Hardware material for exhaust system?

spence88mph · 01-03-2008, 06:34 PM

Again, apologise if this has been covered, just can't find it.

About to mount my stainless headers, turbo etc, should I use stainless nuts on the engine studs? Stainless bolts and nuts on the turbo? It seems the stock ones are mild steel and they may be that way for a reason as they expand and contract at the same rate as the studs?

One more question, as nylock will just cook as soon as it gets hot should I use two nuts or some kind of high temp loctite?

cheers everyone!

les_garten · 01-03-2008, 07:07 PM

Quote:

Originally Posted by spence88mph

Again, apologise if this has been covered, just can't find it.

About to mount my stainless headers, turbo etc, should I use stainless nuts on the engine studs? Stainless bolts and nuts on the turbo? It seems the stock ones are mild steel and they may be that way for a reason as they expand and contract at the same rate as the studs?

One more question, as nylock will just cook as soon as it gets hot should I use two nuts or some kind of high temp loctite?

cheers everyone!

Hi,
I'll tell you what I did. I put stainless studs, nuts, and washers in all those locations. Personally I'd rather have something get a little loose and require tightening, rather than end up with the rusted horror everyone is used to dealing with. When I remove my turbo, I just break the torque and the nut spins off with your finger tip. SS is a little soft though. There will be some folks who will mention that I'm sure. There is also Copper options as well.

You have a good question, I'll be interested in the responses. But I won't be putting anymore Rust Magnets on my motor.

Les

WydRyd · 07:50 PM

Hiya Spence! I believe OEM exhaust nuts are steel with either a copper or zinc coating to resist corrosion/rust and seizure. It's probably zinc as most manufacturers use zinc coatings on their exhaust nuts. BMW use all copper nuts on their M series cars I believe. Zinc or copper coated is best. They never seize up

Use some Anti-Seize on the threads too.

P.S: I'm not sure on using stainless steel on the OEM studs though. Also, s/steel has the undesirable effect of fusing itself to aluminium alloys under extreme temps. I don't think our exhaust studs are of an aluminium alloy... probably just some grade of steel.

spence88mph · 01-03-2008, 07:54 PM

Cheers Merv and Les, would like to just use stainless as they're easy to come by and wont corrode, just dont want them to damage anything.

les_garten · 01-03-2008, 08:50 PM

Quote:

Originally Posted by spence88mph

Cheers Merv and Les, would like to just use stainless as they're easy to come by and wont corrode, just dont want them to damage anything.

By Tomorrow, when everyone wakes up, you'll get a bunch more answers. I don't think the SS would hurt anything. I put it on mine and won't look back. I did the top end on my 250K miles 300TE Benz and looked at the exhaust manifold today and noticed the nuts all rusty again in 4 years and was a little disgusted I had not done SS on it.

Lss

JFairman · 01-04-2008, 09:36 AM

When I installed my K27HFS, I wanted to use new stainless studs on the turbo and the lowest cost way to do it was to buy approx 4" long stainless bolts and nuts and cut the heads off the bolts with a die grinder and death wheel, and slightly clean up or bevel the ends of the threads so they are now very nice studs.

Works great... just be sure to use anti-seize on both ends of the threads so they don't gall and the nuts come off smoothly, and the studs can be removed from the turbo if needed easily in the future.

I'd like to put stainless studs in the heads too but havn't done that.
Some folks say don't do that because of possible galling... so I just used the anti-seize and new 12mm wrench size copper nuts on the stock studs.

Les, I got the stainless metric nuts and bolts at Action bolt and tool in Riviera beach, Fl...

les_garten · 01-04-2008, 10:22 AM

Quote:

Originally Posted by JFairman

When I installed my K27HFS, I wanted to use new stainless studs on the turbo and the lowest cost way to do it was to buy approx 4" long stainless bolts and nuts and cut the heads off the bolts with a die grinder and death wheel, and slightly clean up or bevel the ends of the threads so they are now very nice studs.

Works great... just be sure to use anti-seize on both ends of the threads so they don't gall and the nuts come off smoothly, and the studs can be removed from the turbo if needed easily in the future.

I'd like to put stainless studs in the heads too but havn't done that.
Some folks say don't do that because of possible galling... so I just used the anti-seize and new 12mm wrench size copper nuts on the stock studs.

Les, I got the stainless metric nuts and bolts at Action bolt and tool in Riviera beach, Fl...

Heh, that's where I got mine also! I did the same thing. When I built my motor I bought bags of SS from Fastenal. Everything that can be SS on mine is SS.

Les

David · David's Garage

Austenitic stainless is usually what's available, it's not as strong as OEM and it's prone to gauling so I don't use it. ARP and some others make stainless fasteners which would probably work fine, but I've had good luck with stock fasteners.

JFairman · 01-04-2008, 01:57 PM

I used aluminumized anti-seize from a tube on the threads so I don't think they will ever gaul.
"Coppaslip" anti seize is even better but I used what I have.
The turbo studs are 12mm thick so I'm hoping they will be plenty strong.
They felt real solid when I tightened the nuts down and I have the B&B muffler support strap on there too so we'll see how they work after some time and many heat cycles later...

The origonal exhaust studs seem to work fine, and other people have also talked me out of changing them to stainless so I just coat them with anti seize and hope they don't corrode.