1992 Chevy Blazer Running hot, check gauge light comes on

FLOWERGIRL1

MEMBER
1992 CHEVROLET BLAZER
6 CYL
4WD
AUTOMATIC
16,900 MILES

Hi, we had a problem with thermostat leaking so it was replaced, and then it started overheating. Pulled thermostat and ran without if for a while, changed water pump, new thermostat, continued to overheat. Pulled thermostat and ran without, tried 4 different thermostats. Flushed radiator. Found out that autoparts place sold wrong water pump. Replaced with right waterpump. Put in new heavy duty thermostat. Doesn't overheat, but runs about 250 check gauge light comes on and off. We have tried to purge air, got some out, but that doesn't fix problem. Flushed heater core, has more heat and replaced blower motor relay. Doesn't seem to actually be overheating. Water circulating, Idled for over 30 minutes, with check gauge light intermittent, gauge reading between 240-250, never hits 260. Did not overheat. I'm going to try to replace radiator cap and see if that helps. Somehow I think we are overlooking something. I am in a delivery business, and I have to travel several miles sometimes, and am worried about overheating and damaging the vehicle, and getting stranded in middle of nowhere. Runs great without the thermostat by the way. Please help.

3 Replies

LEGITIMATE007

MECHANIC
5,121 POSTS

Yes, do the radiator cap, make sure your coolant is 50/50, and if that doesnt work, check the engine coolant temperature sensor, its probably faulty, also you must have the correct thermostat in around 195, otherwise it will let it run hotter, I think the problem is probably the temp sensor, but make sure that coolant is correct too.

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Monday, December 29th, 2008 AT 10:22 PM

FLOWERGIRL1

MEMBER
2 POSTS

Put the new radiator cap in, but before that I had to run a few errands and had it running for about 25 mins, it ran about 240 but the check gauges light did not come back on. I took the old cap off and let it run for about 10 mins and it stayed right around 210, it burped a small amt of air out during this time, and I put the new cap on. I let it continue to idle about 10 more mins it ran about 240, but no check gauges light. I noticed a "drip" or more like water going down a drain sound, but not gurgling. When I cut the engine. My son drove it about 20 miles and he said it stayed around 240 but no check gauges light, but it is running sluggish now. I also noticed that the gas gauge is dipping about 1/4 tank then goes back up, but when it dipped the temp gauge also dipped? Would the sensor do that or do I need to look at pricing gauges?

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Monday, December 29th, 2008 AT 10:38 PM

LEGITIMATE007

MECHANIC
5,121 POSTS

No I dont believe the engine coolant temp gauge will cause that, but make sure you've bled the system really good, like take the coolant cap off, turn the engine on and turn heat on high, and let it bubble its way out, after about 20 minutes it should be good, and yes you should test those gauges and possibly replace it, just to rule that out or possibly even solve the problem. You also said that you've ruled out a clogged radiator?

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Tuesday, December 30th, 2008 AT 9:47 AM