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Question About Coolant Loss (1988 Corvette)

What would cause a car to spill coolant from the recovery tank moments after it is started and then turned off? In other words, say you started the car from cold and backed it out the garage – the car ran for a minute or two tops. Then, after a while of sitting, there is coolant underneath. The car engine never really got warm. Then, you receive a coolant low light when you take the car down the road a few miles. The light flickers on and off.

You add water to top off the recovery tank (it is already half full) and proceed to drive for an hour and a half at speeds of 65 to 70 and in bumper-to bumper city traffic. Coolant temps range from 178 to 210 during this trip – higher in city traffic.

You reach your destination and stop the car for 10 minutes. When you return, there is coolant spillage from the recovery tank. You move the car to another parking place, and after exiting the car, you actually see coolant spurting out in short “gulps” from under the coolant recovery tank area – perhaps two or three short gulps. Car has never done anything like this before – seems to have started out of nowhere. Car never overheated and drove fine. Oil stick is clean as new – so is coolant. Called mechanic and said he would pressurize system to check it. Could it be a sticking thermostat? I appreciate your assistance.

Happy Thanksgiving to all!

Replace the radiator cap.

Fluids in an agitated state take up more space. Fluids being pumped are in an agitated state. If you’re topping off your reservoir and your radiator cap is not holding any pressure you could expect some spillage to occur…but ONLY if both of these conditions exist.

Personally, I’d recommend a thorough going over of the entire cooling system and then some including a pressure check, a new radiator cap and T-stat, and a compression leakdown test of the cylinders. Do the leakdown first. It’s also possible that a breech in the headgasket is allowing the combustion chamber to pressurize the cooling system and if that’s the true cause (as I suspect) then you want to know and get it repaired ASAP.