The BEST exhaust manifold bolts?

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Derick

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Back in wintry 2018 I replaced both exhaust manifolds and all the associated bolts. Well a year and a half later and I have an exhaust leak again. 2 bolts have sheered off again. What is the best option for these damn bolts? Also had anyone use the thick graphite based exhaust gaskets that watchjrgo used on the old ford pickup?
 

iamdub

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If you're talkin to me....it was an exhaust shop that did the work so I can't say for certain.

Ah. Too many variables in that situation. Other than specialty applications (headers on high HP cars, etc.), I've always used the bolt kit from Dorman and never had a problem. I use the copper anti-sieze that I use on spark plugs and I torque to factory spec. I even used them on my 5.3 with the headers I just installed. It's possible that they over-tightened the bolts and the two different metals (aluminum heads and cast iron manifolds) expanding and contracting at different rates exceeded their elasticity. Hardware has engineered torque specs for a reason!
 
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Derick

Derick

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Ah. Too many variables in that situation. Other than specialty applications (headers on high HP cars, etc.), I've always used the bolt kit from Dorman and never had a problem. I use the copper anti-sieze that I use on spark plugs and I torque to factory spec. I even used them on my 5.3 with the headers I just installed. It's possible that they over-tightened the bolts and the two different metals (aluminum heads and cast iron manifolds) expanding and contracting at different rates exceeded their elasticity. Hardware has engineered torque specs for a reason!

Yeah I was figuring the same.

These are the gaskets I was talking about. Since they are soft, I think they only torque to like 25 ft/lb

http://catalog.remflex.com/
 

iamdub

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Yeah I was figuring the same.

These are the gaskets I was talking about. Since they are soft, I think they only torque to like 25 ft/lb

http://catalog.remflex.com/

Factory spec for the manifold bolts is 18 lb/ft. Of course, that's with the cast manifolds, MLS gasket and factory bolts. 18lb/ft isn't much, so it's easy for someone doing it by hand to just crank down on 'em really tight. Tighter isn't always better, especially when you have lots of movement such as the expanding and contracting of dissimilar metals. It's why these engines have MLS head gaskets as well. IMO, if you have all factory stuff- manifolds, gaskets, bolts... then there's no need for fancy gaskets and hardware since the OEM stuff lasts well over 100K miles. I think your quick failure was from over-tightened bolts.
 
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Derick

Derick

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Factory spec for the manifold bolts is 18 lb/ft. Of course, that's with the cast manifolds, MLS gasket and factory bolts. 18lb/ft isn't much, so it's easy for someone doing it by hand to just crank down on 'em really tight. Tighter isn't always better, especially when you have lots of movement such as the expanding and contracting of dissimilar metals. It's why these engines have MLS head gaskets as well. IMO, if you have all factory stuff- manifolds, gaskets, bolts... then there's no need for fancy gaskets and hardware since the OEM stuff lasts well over 100K miles. I think your quick failure was from over-tightened bolts.

Yeah I know... But at the same time I acknowledge that tolerances weakened over the 13 years of its life..... So I figure these allow some 'error'.... I figure 50 bucks for a full set of these gaskets and some proper bolts, I feel like it should be good for quite a long time.
 

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