Another 6.0 headgasket question.
Truck has dreaded Black Onyx gaskets and is knowingly sucking coolant.
WE KNOW THEY ARE BLOWN, THAT IS NOT THE QUESTION.
Truck was idling, died and then wouldn't start.
Next day, it started and ran. We turned it off and it wouldn't start back up.
Classic HPO system issue right? Wrong, pressures check out with the AutoE. FICM is fine. Batts hold 12v+.
It sat for the last 2 days, I cranked on it just now to do more diagnosing and after only a few minutes of cranking every few 20seconds it developed
enough pressure in the system to hiss out the cap at me.
So, that would confirm terribly blown HGs right? And would that keep it from starting?
No white smoke, no nothing. It just cranks away and builds up pressure in the coolant system. It is 50*F and the truck is
still cold, so why would it build PSI when cold and not start????