Exhaust Manifold Stud Failure
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Senior User
Joined: Dec 2001
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Exhaust Manifold Stud Failure
2002 F250 5.4
Concerning these engines with the manifold mounting studs failing from corrosion .....
I really can't see anything, it appears they are all still there, but ....
if a few did break at the head, and the manifold is starting to warp or whatever ...
might it sound like a faint valve tap or similar? And as the engine gets hot, the sound goes away?
thanks
Concerning these engines with the manifold mounting studs failing from corrosion .....
I really can't see anything, it appears they are all still there, but ....
if a few did break at the head, and the manifold is starting to warp or whatever ...
might it sound like a faint valve tap or similar? And as the engine gets hot, the sound goes away?
thanks
Logistics Pro
Joined: Mar 2002
Posts: 3,881
Likes: 84
From: Wake Forest, NC
Jim, you got it head on.
I would really advise to have the manifolds milled. IIRC, there is not a gasket or it is an MLS gasket, either of which need a good surface to seal. If the studs have broken, either from corrosion or warping, the manifold will be warped. So get it flat! Some may get away with just replacing the studs one at a time, but I wouldn't do the job without milling the manifolds.
I would really advise to have the manifolds milled. IIRC, there is not a gasket or it is an MLS gasket, either of which need a good surface to seal. If the studs have broken, either from corrosion or warping, the manifold will be warped. So get it flat! Some may get away with just replacing the studs one at a time, but I wouldn't do the job without milling the manifolds.
Hotshot
Joined: Mar 2007
Posts: 10,101
Likes: 40
From: Pa
The studs are stainless steel from the factory. The exhaust manifolds are also cast stainless steel. The studs do not break from rusting. The expansion and contraction from the manifolds from many hot and cold cycles stress the tiny M8x1.25 studs and will eventually cause them to shear off. It is a common problem.
I recently put headers on my 04' 6.8l with 27k on it and it had 1 stud broken off level with the head. I kept one of the studs and there is no rust on it whatsoever, (as with the rest of them) I can post pics.
My dad had 6 shear off on his 03' 6.8l as well.
I recently put headers on my 04' 6.8l with 27k on it and it had 1 stud broken off level with the head. I kept one of the studs and there is no rust on it whatsoever, (as with the rest of them) I can post pics.
My dad had 6 shear off on his 03' 6.8l as well.
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Lead Driver
Joined: May 2003
Posts: 9,303
Likes: 48
From: Lyndonville, Vermont
In 03 ford went to SS studs. Earlier are all steel..As are the manifolds regular cast iron 03's included..I replaced manifolds also.
Dick
Dick
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Hotshot
Joined: Mar 2007
Posts: 10,101
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From: Pa
Originally Posted by 99f350sd
In 03 ford went to SS studs. Earlier are all steel..As are the manifolds regular cast iron 03's included..I replaced manifolds also.
Dick
Dick
The 400 series stainless used for the studs and nuts will get a little surface rust as well as the manifolds, but they are still a stainless alloy.
Hotshot
Joined: Mar 2007
Posts: 10,101
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From: Pa
Originally Posted by 99f350sd
Nope................
Lead Driver
Joined: May 2003
Posts: 9,303
Likes: 48
From: Lyndonville, Vermont
There was a tsb in 03 stating that stainless studs were avail...Never heard of stainless manifolds since being on here..5.4 or 6.8..I suppose something could have slipped by me but I doubt it.
Dick
Dick
Hotshot
Joined: Mar 2007
Posts: 10,101
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From: Pa
Originally Posted by 99f350sd
There was a tsb in 03 stating that stainless studs were avail...Never heard of stainless manifolds since being on here..5.4 or 6.8..I suppose something could have slipped by me but I doubt it.
Dick
Dick
Lead Driver
Joined: May 2003
Posts: 9,303
Likes: 48
From: Lyndonville, Vermont
Someone in the past has said that the exhaust was stainless but that was the pipes not the manifold..as many v10 guys were replacing their cracked manifold and rusted one's. A magnet won't stick to the new studs...if they are stainless.
Hotshot
Joined: Mar 2007
Posts: 10,101
Likes: 40
From: Pa
The stud off my 04' is magnetic and it is stainless. (Just checked it) The studs are made out of a mildly magnetic 400 series stainless as are the manifolds and exhaust pipe. 400 series does not have the higher nickel and chromium content of the more expensive 300 series stainless which is truely non-magnetic, will never rust but is also not able to be hardened like the 400 series due to the higher alloy content and low amount of carbon.