I've read about bleeding the cooling system by opening the screw on the thermostat housing. Is the engine supposed to be running or not when I do that and should the thermostat be open or closed (cool/hot engine)? How do I know when the air is out?
Enthusiast
I've read about bleeding the cooling system by opening the screw on the thermostat housing. Is the engine supposed to be running or not when I do that and should the thermostat be open or closed (cool/hot engine)? How do I know when the air is out?
1995 Chevy K-2500 extended cab shortbed, 4L80E, 6.5 Turbo 182,000 miles, 3.73 gear
110K 3" Flowmaster turbo downpipe / 120,000 Heath Diesel PMD relocator kit
122K OPS Relay, New CDR valve, New Lift Pump and OPS / 130K New Harmonic Balancer & Crank Pulley / 173K Pro Comp LT265/75/16 / 181K Mechanica Boost
If you drain the radiator you introduce air into the system. The air gets trapped in the thermostat housing because it is a high spot. Enough air will prevent the thermostat from sensing the water temperature correctly. Refill the system then start the engine and open the bleeder until water starts coming out. Close the bleeder and wait until the thermostat opens (top hose gets hot) then bleed it again. When air stops coming out, the air is out. (Yogi Berra)
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