I have a 1994 Chevrolet K1500 5.7L Silverado 4X4- Leaving home for work this morning I didn't even have a puff of warm air through the vents...figured I'd drive a little ways and see if it worked itslef out. Then the truck started running hot (Have a Hypertech Thermomaster chip and 160degree thermostat) and it usually runs around 140-150. Anyways, I figured itwas probably an air-lock in the system so I parked it on an up-hill slope and tried purging the system (ran motor with rad cap off, repeatedly squeezed bottom rad hose to work the coolant, and kept the coolant topped off) It's been quite cold here in Montana for a few days now (0-10) and my guage temp has been occasionally climbing to 190 (while driving) then dropping back down. I don't know if the following is normal but as I was purging the system I went to turn the truck off when it got to 190-200 and did not have the rad cap on, coolant shot everywhere. Is that from normal pressurization? Or is there possibly a blockage? Any help would be greatly appreciated! Thanks for taking the time to read this! -Patrick
First off the thermostat is way to low of a temperature you are wasting fuel. That said you either have a p[lugged heater core (very unlikely) or you have a air temperature control blend door problem.
SOURCE: GUAGE SHOWS HOT
is it ever low in coolant? i agree with emissionwiz sounds like your getting airpockets do you have heat when this starts?
SOURCE: no heat 98 gmc pick up just cold air
their is a heat control valve that is by the top of the wheel well it works off vacumme if its not working you wont get heat
SOURCE: 1994 Chevy Silverado temperature guage shows hot
Flushing the radiator, replacing the radiator cap, adding new coolant, replacing the sensors and a new thermostat solved the problem. Probably didn't need to do all of these things - but since we just purchased the truck, and given the fact that is probably hadn't been done in a while, we chose to do all of these things (which really didn't cost a whole lot), it's running like a charm now.
SOURCE: Engine Coolant Hot Message Noticed AC was
I wouldn't think it would be the water pump mostly because they will either start to get noisy, pour coolant out of the seep hole or completely seize all of which you would probably notice. My guess would be that you have air in the system that may be causing the thermostat to remain closed or possibly a bad radiator cap and/or faulty fan clutch (usually when they "fail" they stay engaged all the time but it is worth inspecting. I was taught to ALWAYS drill a small bypass hole in the rim of ANY thermostat I replace. It helps to gradually open the thermostat during warm up and if the thermostat fails to open, there is still a passage for coolant to flow. This is a must for any GM vehicle.
SOURCE: Issue with coolant system: Issue
AFTER REPLACING THERMOSTAT DONT STOP OVERHEATING.CHECK THE COOLANT FAN CLUTCH.WITH HOT ENGINE THE CLUTCH FAN SHOULD HAVE RESISTANCE WHEN TURNING IT WITH HAND.IF NOT FREEWHEEL.FAULTY CLUTCH FAN.HAVE TO REPLACE CLUTCH ON FAN.BAD CLUTCH ON COOLING FAN WILL CAUSE ENGINE OVERHEAT.WHEN CLUTCH FAN FREEWHEELS AT HIGH SPEEDS NOT PULLING ENOUGH AIR THROUGH RADIATOR CORES TO COOL DOWN ANTIFREEZE AND ENGINE.
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