My 1988 turbo 114k recently started having boiling coolant in the overflow tank when letting the car run for about 15 minutes. Temp gauge shows normal range. After letting the boiling settle down (apx 5-6 min), I use a turkey baster to return the coolant to the radiator. Thus returning the overflow tank level to "cold level." Next morning after 15 min run time it's the same thing. I have checked for coolant in the oil, white exhaust, no air bubbles in the radiator neck, and today I'm going to pickup a hydrocarbon testing kit. However, I don't believe the problem is a blown head gasket just yet. The car runs good and has not overheated after a 100 mile drive in 95+ temps. Any ideas?
coolant reservoir boiling
- Thread starter rbzbozzy
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why isnt the coolant being automatically returned to the radiator when it cools down? Check if you have the correct radiator cap and rent a pressure tester with an adapter to check the cap to see if it is holding pressure at it's rated psi.
92 Sunbird LE
Well-known member
Cooling fan coming on? If yes , pull out the thermostat out of the engine cooling cap neck with pliers and try it without it.( It may not be opening all the way)
Doug in P.R.
Doug in P.R.
Haven't had the time lately to run down some ideas about the boiling coolant. i did order a hydrocarbon test kit to check for head gasket failure. Just went through that with my 03 Honda Odyssey. The symptoms on the ody were white smoke in exhaust, multiple misfire codes, bubbles in the radiator neck, and stumbling at startup. But no boiling water in the overflow reservoir as I now have with the Sunbird. The car runs in the middle on the temp gauge and does not seem to be overly hot. Starts and idles well. I'm onto checking the radiator fan because after running for about 20 minutes (air temp 92%) the fan motor never started up like I would think it should.
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92 Sunbird LE
Well-known member
Hopefully it's just the relay ( on the drivers side fender) or the fan motor itself. My fan motor has stopped twice and I took it apart both times , cleaned it out and it started working. It sometimes builds up with road debris oil and and/or engine oil and stops working.
If it is a computer signal problem like mine had originally, you might have to wire up a switch or aftermarket fan controller.
Doug in P.R.
If it is a computer signal problem like mine had originally, you might have to wire up a switch or aftermarket fan controller.
Doug in P.R.
Bill the Engineer
New member
Head gasket? A defective thermostat can blow the head gasket and cause this. make sure you aren't flooding the oil pan with coolant!