Exhaust Manifold Leak

[bigbrother44]

I also have a minor crack in my left exhaust manifold. I never worried about it because what kind of problem could it cause? Let a little exhaust out ahead of the catalytic converter? If anything, this should be good...a little less effort to get the exhaust out = less HP wasted on pushing the exhaust through the catalytic converter, right?

Then somebody told me something I'd never heard before. A leaky exhaust manifold can damage your heads??? Something about the cold air being sucked into the hot exhaust manifold then into the head? But doesn't the exhaust cycle by it's very nature only let exhaust out, not cold air in? I still don't follow the logic, but maybe someone could help me out here. I think the guy may not know what he's talking about. But then it could be me that doesn't know...

[Pontiac1976]

Well this can open up a few can's of warms. All so a lot of views.

Well short term not to bad. but can lead to bad head valves seals guides Just name a few. If the leak on the top near the valve cover it can dry out the gasket make them leak oil.
That cylinder will be hotter then the ones not leaking because it suck air makeing a leaner run cylinder.
the noise can make you miss when the other parts are getting bad.

[bigbrother44]

Maybe I'll be scrounging the $109 (plus tax of course, this is CA) that Kragen wants for the lifetime warranty exhaust manifold...