Exhaust question

can a cracked exaust manifold (aka headers) lead to the failure of the head gasket?

Nope.

Headgaskets fail either because of warpage of the heads (typically due to overheating, in some cases due to bad design) causing apots in the gasket to be not properly compressed to withstand combustion forces.

In short, blown headgaskets are the resuult of overheating or bad design.

The exhaust manifold is external to the combustion chambers and to the water jacket and headgasket. It’s totally irrelevant to the headgasket.

thanks we just replaced the head gasket on a 1986 toyota corolla gt-s and the owner before us (who just happens to be my uncle) said not to drive it because the cracked headers caused it to fail. i just think that it was a cheap gasket on there like the rest weve had to replace

Headers on a Corolla?? Why?

or exaust manifold what ever theyre called on 4 cylinder cars lol

Hmmm, a crack in the exhaust manifold will cause hot exhaust gas to be applied to places it dont belong. Depending on where the crack is, it could cut through the exhaust manifold gasket. That gasket faces between the head and the exhaust manifold, maybe that was what yer uncle was indicating?