bad87vette

Hi, I have an 87 and when I warm up the car or when I drive and it reach the temp at 180~190 (thermostat opens) low coolant warning light comes on I already replaced the following:
1) new radiator and I also burp the air out 2) new low coolant sensor switch 3) replaced leaking heater control valve 4) tested and passed the cooling system using radiator pressure tester 5) new radiator cap (16PSI)
I burped the radiator out multiple times no luck need your help please. Before warming up the car I checked the coolant level on the radiator and is full I also checked the coolant level on the reservoir no change hot or cold.

kenmohr

Look for leak that lets it suck air back in instead of the fluid from the recovery tank. Try a pressure test. Had a hell of a time on my 89

Whaleman

Either the sensor is bad or you are low on coolant. Since it comes on when the thermostat opens leads me to believe it is low on coolant. Dan

vader86

If you've burped, filled to the top, then I'd suspect the overflow tank.

Otherwise are you seeing any white smoke out the exhaust? Anything in the coolant or oil?

WVZR-1

If the 'Coolant Level Sensor' was a 'LOCAL' purchase I'd consider asking for a replacement. Easy enough to replace!

bad87vette

Thank you all for your helpful responses low coolant warning light came on with the original coolant sensor so I replaced that and still coming on, the radiator cap is also
new 16PSI pressure. I don't see any with smoke and no water or coolant on oil stick I also checked the valve cover cap for water residue ...nothing. I even check the water level on the radiator before starting the engine at all times. As I mention before that I pressure tested the radiator and pressure stayed @15 PSI for 5mins checked for leaks none found. Again thank you all for your help and responses I will update once I figure this thing.

Siveck

Did you elevate the front of the car during coolant fill?

84 4+3

Have you started the car up cold with the cap off to see what it's doing as it warms and opens? I've had to do that on my 84 a couple times to get the system full. Just a thought.

bad87vette

Thanks for your response yes it is elevated I had it on a ramp....I started the car without the cap once it started warming up the coolant would slowly overflow so I had to put the cap on.

kenmohr

"I also checked the coolant level on the reservoir no change hot or cold."

This level should change from cold to hot and then from hot to cold. It is the way the car self burps the final air out and maintains the level. you have water exiting and air entering from somewhere Were there 3 o ring seals on the probe ( sensor on the radiator )

yakmastermax

My 1989 just starting throwing the low coolant light. Radiator and overflow tank are full. Goes off by itself shortly after car is sufficiently warmed up.

Bob89c4

My 89 also just started doing this as well. Reservoir is full, so is the radiator. after taking it on a 20 min drive I come back, the radiator is cool to the touch and can be opened the top radiator hose has no pressure and is els o cool to the touch. The temp was between 186-189. Im wondering if I have some sort of blockage or thermostat is bad/not functioning. The water pump was replaced shortly after buying the car but thats been a while ago. No loss of coolant on ground or in engine compartment.

Bob

car addict

My car is a 96, so apples and potatoes. But my car did something very similar after installing a new (AC Delco) thermostat. New thermostat was defective. Only opened a little bit - not fully. So car ran hotter than usual and didn't overheat. I could put my hand on the radiator.