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exhaust manifold studs

tmaxx411

Proven Member
115
0
Dec 17, 2010
Manasquan, New_Jersey
There's a reason why no OEMs use stainless studs or bolts with aluminum parts.


and why would that be? i see no real disadvantages with using them. and the exhaust manifold is cast iron i believe, not aluminum
 

ramsack

Proven Member
3,286
16
Dec 27, 2007
West Lawn, Pennsylvania
The head is aluminum, and stainless causes aluminum to corrode.
 

ramsack

Proven Member
3,286
16
Dec 27, 2007
West Lawn, Pennsylvania
Yeah, it's so simple, that's why so many auto makers have done this...not.
 

ramsack

Proven Member
3,286
16
Dec 27, 2007
West Lawn, Pennsylvania
Actually, a lot of OEM exhaust pipes are stainless (yes, stainless DOES rust, just slower than plain steel). Manifolds being stainless is the only good example of cost, being a massive part. They don't use stainless hardware in aluminum because of galvanic corrosion.
 

bryanwheat

DSM Wiseman
7,110
177
Aug 16, 2004
Columbia, Missouri
Actually, a lot of OEM exhaust pipes are stainless (yes, stainless DOES rust, just slower than plain steel). Manifolds being stainless is the only good example of cost, being a massive part. They don't use stainless hardware in aluminum because of galvanic corrosion.

Actually some manufacturers DO use stainless steel manifold studs. Ford switched from coated steel, to a stainless steel around 2001-2003 for their 4.6 and 5.4 modular engines. The old ones would rust so bad that they would literally snap and fall out when driving.
 

ramsack

Proven Member
3,286
16
Dec 27, 2007
West Lawn, Pennsylvania
Good for them. They're either complete dumbasses or they went the extra mile and have the holes lined with steel thread inserts. Stainless steel threaded into aluminum is a bad idea.
 

T is for TURBO

Proven Member
2,251
20
Jan 15, 2005
Milwaukee, Wisconsin
Doesn't galvanic corrosion require a conduction solution in order to occur? Like a water, or very salty air (like coastal regions?) Being that it is on the hottest part of the manifold, I would think it stays pretty dry... Maybe I'm wrong though, it's been a long time since I took high school chem.
 

ramsack

Proven Member
3,286
16
Dec 27, 2007
West Lawn, Pennsylvania
Unless it's in a vacuum, it's constantly exposed to something somewhat conductive.
 

bryanwheat

DSM Wiseman
7,110
177
Aug 16, 2004
Columbia, Missouri
Good for them. They're either complete dumbasses or they went the extra mile and have the holes lined with steel thread inserts. Stainless steel threaded into aluminum is a bad idea.

Well it solved the problem with the studs rusting out. If you have ever removed a manifold from a mod motor with the mild steel bolts than you would know that 95 percent of the studs will snap off in the head from being rusted. With the ss studs that doesn't happen.
 

ReYnd

Proven Member
402
4
Dec 8, 2009
Deep Water, West_Virginia
I have been using the SSS all stainless kit for a few years now. Used a small screw extractor to remove an old stud that was broken off below the head's surface. Coated the threads of the new studs that were going into the head with nickel anti-seize, installed them, and I foresee no problem.

Even after those 15 to 20 years, I'd say a couple seized exhaust manifold studs (which are stainless, meaning they're very unlikely to give you trouble anyway, even in terms of heat cycling and embrittlement) are the least of your worries. What's there to lose? Maybe strip the head and have to repair it.

That said, the FFWD/ARP set is probably nicer, but I couldn't justify the price difference for a hex broach; the double nut method works fine. There's still an unused bag of OEM studs/nuts/washers kicking around here somewhere...
 

serviceguy

Proven Member
571
35
May 11, 2002
Clifton, New_Jersey
I just bolted my exhaust manifold back on. Back in 2003 I used a SSStuds kit (I believe back then they shipped SS locking nuts that I stored in my toolbox and used some regular SS nuts instead, but I am not 100% positive on that, other than I have a set of SS locking nuts in my toolbox whose source is not accounted for). Unfortunately back then I over-torqued one of them and stripped the hole in the head, this time I decided to time-sert (regular inserts, not SS) all the threads in the head (with the exclusion of the lower-center one that plugs in the oil galley) and reused the SS studs. I spiced it up with an embossed copper gasket. I'll let you guys know in 25 years how it goes:thumb: jokes aside, i always used nikel anti-seize and did not have any problem removing the studs. Galvanic corrosion is not a matter of opinion, it will happen. How that is going to affect the bond of the stud with the head and over how much time is another story, Ford probably thought it would outlast the life of their rust buckets anyway! J/K!
 
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