Coeficient of linerar expansion.

[Plowman]

If the bolts snap off flush with the head the engine has to what...

[jannes_z-28]

I had that problem on an Opel with the 2.0 Ecotec engine. The explanation was that the manifolds bolt hole were a little to tight and when hot expanded and pinched the bolt and pulled it. Eventually the bolt would snap at the head. As mine did, the mechanic were able to repair it without pulling the engine. Small engine, big car = lots of room to work.

GM was aware of the problem and on later models they made the hole in the manifold slightly larger so that the bolt would not stuck in the hole.

Jan

[Plowman]

So GM was aware of the problem later so they fixed it for you under Warranty.

[jannes_z-28]

Warranty had run out when I got my problem.

Jan

[300deluxeL79]

very common (broken ex bolts) on the truck LS engines. probably due to using too small a bolt dia. 8mm/5/16".
my '03 K1500 5.3 has the rear bolt snapped off on both sides when i bought it. they don't leak.

[Plowman]

The problem is to get the broken bolts out.