Failure mode - GM 6.0L V8 Gasoline (GM HD, LY6-L96 2008-2019; Express/Savana vans 2008-2020)

Cooling system wear: water pump, fan clutch, thermostat (L96)

Reliability tier: aggregated - verify before ordering, see /disclosure/

Symptoms

coolant seepage at the weep hole, bearing growl on the pump
overheating under tow traced to a locked/loose fan clutch
thermostat housing leaks at high mileage

Compare with the other causes of the same sign on this engine: losing coolant · overheating or temperature creeping up · ticking, knocking, rattle or whine (4 causes)

Root cause

Water pump seals and bearings wear with tow-duty heat cycles, fan clutches lock or slip, and thermostat housings leak at mileage - ordinary wear items that surface under load on high-mileage work trucks.

Diagnosis

pressure-test the system; verify fan-clutch engagement under load
inspect the thermostat housing and radiator seams before replacing the pump

Fixes

replace the failed cooling component; bleed per procedure ()

Prevalence

occasional

Parts for this repair run about $40-$380: see them next to the other repairs on this engine in repair costs.