porshapower

Hi, My low coolant message is on and its full of coolant. I have a 1988 and see a sensor on the radiator (passenger side of vehicle) with 1 wire. Is this the sensor for the low coolant message or for the fans to turn on? How does this sensor remove from the radiator..mine just spins and spins. Thanks in advance.

PAINTER MAN

Chances are there is nothing wrong with the sensor. You have to pack the radiator on a 88. Start the car, turn on the heater, and when it reaches operating temperature remove the cap and add coolant.

AGENT 86

When it reaches operating temp(stat open), open rad cap, hold RPM to about 2000(reach over to throttle body or have a helper hold gas peddle) then add coolant until full.
Replace cap then return to idle RPM.

eaglevision993

Don´t remove the cap when hot! Loosen the cap with a cold engine and let it idle until operating temperature. Then, remove the cap, get the RPMs up to 2000.
You can stick something between the throttle lever and its resting point.

The coolant level will be low with the thermostat open and the RPMs at 2k.
Now fill the radiator until full and replace cap BEFORE letting off the throttle.

Having the front on a ramp or jacked up helps.
I just installed a new radiator in my 88 2 days ago and did the procedure exactly as descibed.
Best regards
Benjamin

porshapower

Thanks for all the help! I will try this tomorrow. Thanks again.

pmihaltian

Here is a pretty good write-up on How To burp your early C4 radiator.

robsball

I did this just last night for the same reason....low coolant light came on intermittently. P

Open the rad cap when the engine was cold and put the Lisle funnel in the mouth with the correct fitting. Started the car. When the car's temp got to 215(remember fans don't kick on till about 228) the coolant started to boil up and out of the funnel.

Shut the car off and ended up by passing the temp fan relay with a paperclip that kept the fan on all the time and started the car back up. This time the coolant did not boil and was able to fill the radiator with coolant. Rev'ed the car up to 2000rpm and I could see it burping....air bubbles coming out. Once filled to the brim, let it run until no more bubbles.

Removed paper clips and put everything back.

vetteoz

Way too hot ( and dangerous ) ;
only need hot enough to get the thermostat open

Cliff Harris

Under the category of "mysterious C4 things" is that the low coolant light can sometimes be fixed by replacing the radiator cap.

Theoretically you don't need to burp the cooling system. The air is in the top part of the engine in the thermostat area. When the thermostat opens, the air gets pushed through the upper radiator hose into the radiator and out through the radiator cap. When the engine cools down, water is drawn from the overflow tank and replaces the air. After several heat/cool cycles all the air will be out of the cooling system. Thus the new radiator cap as the fix.

I was wandering around Corvette sites and happened to see a picture of a coolant level sensor, like this:



After you remove the electrical connector, I believe it just unscrews. Been a while since I took mine out and I don't remember.

robsball

I agree about it being dangerous, and it made a big mess.

Bear in mind this was a head gasket replacement several months back, new radiator, new water pump and thermostat. Found the sensor broke with black tape wrapped around it when I got car back. Was a cheap part, so I just bought it and replaced it.

Was driving tonight and unfortunately the low coolant sensor light fired again for about 3 mins then went out. Temp was 202.

Wondering if sensor is failing? I had planned to flush and replace the coolant in the very near future.

porshapower

Light is out! Did what you guys said and held the rpm while filling it and then put the radiator cap back on before letting idle down. As far as the sensor unscrewing? Seems like the one on the radiator of my corvette just spins and spins.. I was playing with the sensor before I asked about the low coolant message here and I stopped when I could not remove it. Thanks again.

robsball

Wanted to post this. I just purchased this book from EBAY

http://www.ebay.com/itm/270891161555...84.m1497.l2649

I was reading and one of the things its said was the C4s(especially 89s) were famous for the low coolant sensor light to come on intermittantely even though the antifreeze level was good. It is caused by contaminated fluid. My 89 still lights on occasion(after burping) even though the level is good, but I do know the fluid is contaminated as it has a brownish green tint and a flush is in order.