'98 sc2 Low coolant light/Coolant overflow blow

Hi all, Driving my car today, after 15mins the coolant resevoir started to spew coolant from the cap....Now the car never overheated...the coolant temp gauge was between 1/3 and half....and the low coolant/temp lights started to flash......I pulled over, let it cool, filled it with water to the proper level...went on my way....the low coolant light stayed onfor a few more minutes, then went off, then came back on....the coolant stayed the same level....got home, let it cool..level normal....turned it back on and the light came on again.....I guess my biggest question is what caused the over flow to boil over? Is it a sticky thermostat? would that cause it? And second, why is the low coolant light going on and off? Any help would be greatly appreiciated. Thanks All....

Oh, one other thing, I had the oil changed 2 days ago and I believe the top off all the fluids...don't know if this makes a difference. THanks again.


'98 saturn sc2

Hi all, Driving my car today, after 15mins the coolant resevoir started to spew coolant from the cap....Now the car never overheated...the coolant temp gauge was between 1/3 and half....and the low coolant/temp lights started to flash......I pulled over, let it cool, filled it with water to the proper level...went on my way....the low coolant light stayed onfor a few more minutes, then went off, then came back on....the coolant stayed the same level....got home, let it cool..level normal....turned it back on and the light came on again.....I guess my biggest question is what caused the over flow to boil over? Is it a sticky thermostat? would that cause it? And second, why is the low coolant light going on and off? Any help would be greatly appreiciated. Thanks All....

Oh, one other thing, I had the oil changed 2 days ago and I believe the top off all the fluids...don't know if this makes a difference. THanks again.


'98 saturn sc2

I'm betting you have a bad coolant lid. Try replacing it since it's cheap (less than $10) and make sure you have at least a 50/50 blend of antifreeze/water.

Thanks Ruley73, I will try that.....It looks good, but for $10, can't hurt to try.

Thanks Ruley73, I will try that.....It looks good, but for $10, can't hurt to try.

I'm thinking your coolant lid is no longer holding pressure (15 PSI) like its supposed to, causing the coolant to boil at a lower temp than it should. The lid can look perfectly fine but be bad. FWIW I've had to replace the cap on all 3 Saturn S-series cars I've owned. It's one of them little things that go bad, but cause symptoms that appear to be more serious. I think it's because a lot of people don't realize that the coolant lid is more than just a lid.

The low coolant light is blinking because the coolant level sensor uses a float that is integral to the coolant reservoir, and when the coolant is boiling, that float is probably bouncing a bit.

I had this very thing happen.. I was driving home.. got stopped in traffic on the hwy and noticed steam coming from my reservoir.. pulled over looked at it.. the relief valve on my reservoir was venting.. not hugely. .but very noticeable .. I could smell it as well.

So the temp gauge never actually went over half.. and I thought initially it was the reservoir.

My case it was actually overheating and it was the temp sensor that was malfunctioning.. I was lucky I didn't do any damage. It wasn't reporting correctly thus the fan wasn't kicking on when it needed to and causing the coolant to overheat and the pressure relief to let her go.

You may want to have that looked at.. as it was said to me these things almost always fail at some point. they are inexpensively replaced and for peace of mind you may want to consider it while looking for a replacement reservoir.