I was wondering if a cracked exhaust manifold could be causing the noise and overheating I was talking about in the previous thread I posted about the whistling and whining noise? I just notices there is a pretty good crack near the back of the manifold, and quite a bit of air is coming out at idle. If this is the culprit, why would this cause overheating?

 

Exhaust flow does drive the turbo impeller. Guess I'm not sure to what degree escaping exhaust psi would effect a overheat condition. Are you experiencing high EGTs for a prolonged period? That would drive coolant temp up. What year truck do you have? Fill out your signature with that info. Restricted radiator fins are a common prob for overheating also.

 

A cracked exhaust manifold will not cause any overheating. High EGT will crack the exhaust manifold. Also, all OEM 5.9 Cummins exhaust manifolds will eventually crack if the engine is worked at all or fueling enhancements are made and then used.

As far as overheating, I missed your other post on this, but what are the particulars on the truck such as engine year, which transmission, and any aftermarket speed/power enhancements?

Does the overheating correlate to high EGT's, or is it coolant overheating? Does it overheat under load, or just over time?

 

The previous thread I posted was "whistling, squealing, whining and overheating".