I could use some help and direction here
I have a 2006 Isuzu NPR with 6.0L GM gas engine.
The truck overheated on a delivery run, after the engine support crossmember dropped on one on one side, stopping the mechanical cooling fan and clutch, puking water into the overflow can.
Returned to shop, lifted and bolted the cross member back into place. Still overheating...
Replaced in order- thermostat, radiator, fan clutch, upper and lower hoses, water pump, both head gaskets (after negative 8 cylinder leak check and no carbon in cooling system) Found one head gasket installed incorrectly front to back and reinstalled verifying both correct.ee
Lastly installed coolant temperature sender at left front head, no change.
Starts and idles at normal temperature. Temperature increases in relation to speed, approaching 235 degrees at 70mph and triggering knock sensor bank 2 (both sensors replaced as well)
I'm at a loss here. What am missing here?
Was thinking possible timing advanced to far causing detonation. ECM is stock.
Thanks for ANY insight
Regards Jim Herron