Sounds more complicated than your first post. Find a good certified mechanic.

When he fires it up does it smoke white for a bit? More than normal I mean. I had that happen on a cat 6nz engine, it was failed gasket and cracked head. Cost the boss a lot to fix, but it would of meant a new engine if the problem wasn't taken care of right away. Get it into a good mechanic asap.

he probably already checked, but if not check the dipstick. if the oil looks grey or milky it could be the oil cooler. also, need to make sure there is no oil getting in the coolant as well if the coolant is looking funky there may be oil getting in.

If the engine is locked up it is a head gasket or cracked head or both . A bad thermostat wont lock it up nor will a bad water pump.

Thanks, that's what we thought. It's at Cat now and they are looking at it today, looks like a cracked head will most likely do overhaul. Anyone know if that will mean the PDI tune will be gone after they do it?

the tune should stay unless they reflash the puter on it .

They have no reason to flash it no paremeters need to be changed if it buing rebuit to it's same specs. They only put new flash on if you pay for it. So just make sure they not paying for the new flash updated files from Cat v

Detroit will reflash the ECM with a lo NOX program without telling you, he needs to have a talk with Cat and make it clear that they only change hard parts, no touching the ECM. Your the one paying them, get what you want.