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Discussion Starter · #1 ·
Can anyone explain to me why this could have possibly happened or what the problem might be?

The other day I found these two bolts on the concrete where the truck had just been...



Today I looked under the hood and saw where they were supposed to be...
 

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I ran into the same thing on a 3rd gen I worked on. The problem was the exh. manifold warped causing the bolts to break
 

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exhaust manifold studs go through alot of abuse. exhaust gets very hot. metal expands and weakens. hopfully u have egt gauge. maybe ur running too hot.
 

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Expansion and contraction caused fatigue.

IIRC they used to have problems with the exhaust manifold cracking, my guess would be they beefed it up but did not address the root issue. When you remove the manifold to extract the old studs, I would suggest opening up the bolt holes in the manifold some to allow room to expand and contract without pushing and pulling on the studs.
 

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Discussion Starter · #7 ·
Just got all the gauges, just need to hook up the pyrometer sending unit yet... This might just be the perfect time if I would have to remove all that stuff.
 

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you dont need to fix it if you dont mind an exhuast leak. but to fix it you will need to pull the manifold off. if your luck part of the bolt is sticking out if not get a good easy out
 

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Does anyone make a higher grade manifold bolt, like ARP?
 

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there's nothing wrong with the manifold bolts... what happens is when the manifold shrinks so much, it will shear the bolts off... this is why they make multi-piece manifolds.

on a 12v, in severe cases, it will actually crack the ears on the HEAD
 
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