seeking advice,all the used heads i have looked at have cracks.do they all have to be welded? is there any other options.the cracks run between valves. is this a common problem whith the 6.5 thanks in advance.

This is a common problem with the 6.5 heads. The passanger side with the turbo usually goes first. I went through this last year and learned allot. The fix is a crossover tube between the valves coolant passage and a cosmetic weld for the crack. My former employer worked for the Air Force as a mechanic and confirmed this same problem with the hummers. I put the better fel-pro gasket on when I replaced my heads. Make sure you tell them them if the engine has a turbo or not, the pre-chambers are different.

I've read diesel automotive services site where they describe what it takes to weld the heads. They slowly bring the head to welding temp(just cooler than white hot) to work it.


The hummer should be less prone to the cracks with a more balanced exhaust system.

I agree the hummer is less prone to the cracks, but still eventually happens. And yes, they do heat them up to welding temp before welding. I personally replaced my radiator and upgraded to the bigger water pump when I replaced my heads. Just have to upgrade to the dual thermostat unit now. Hoping she runs cooler on those pulls up the hills pulling my TT.