Quote:
Originally Posted by bbaCJ8
At a guess, it's an issue of differing materials with differing coefficients of thermal expansions. Aluminum expands and contracts at different rates than cast iron, which expands and contracts at different rates than high strength steel bolts/studs. Add in some galvanic corrosion and extreme heat cycles and you've got a lot of stress. Maybe even stress corrosion playing a role. Or maybe they just spec'd out the wrong kind of fastener. Something too strong may be too brittle to survive the heat cycles and varying CTEs over time. Something too soft that easily survives the varying CTEs may not have enough ultimate strength to survive.
|
Quote:
Originally Posted by Blue XJ
Now that's an engineering answer if I ever heard one! But I agree 100%. The manifold design plays a role in it too, it's really only common on the trucks, the cars dont see stud failure as often. I assume the truck manifolds might be thicker in the mounting area not allowing them to expand/contract as much as the car manifolds.
|
I agree, but why the issue on the 6.0L and not the 5.3L? I haven't looked into the differences between the manifolds on the 1500 vs 2500 but it is still odd in my mind...especially for how common it is on a 6.0L
