Help Coolant Overflows
Thread Starter
Burning Brakes
Joined: Apr 2004
Posts: 810
Likes: 1
From: Las Vegas NV
Help Coolant Overflows
On the way to work today, I got into the Vette (96 Coupe) started it up everything was normal. Got on the highway and the "Low Coolant" light flashed on and off intermittently. Checked the guages temperatures were normal (200 to 210). I stopped opened the hood looked for a leak and couldn't find one. As I sat there idling the temperatures stayed normal (200 to 210). I got on the highway, "Low Coolant" flashed on and off a couple of times, drove about 20 miles to work. All temps normal. I stopped in the parking lot idled temperatures were 200 to 210. I opened the hood and I noticed that the coolant overflow tank was over full. The only work that was done to the car recently was a free lube, oil and filter change at the dealer this weekend with Mobil 1. Topping off all fluids was part of the service. Any suggestions?
Instructor
Joined: Jun 2002
Posts: 103
Likes: 0
From: Pasco WA
I had an 89 that flashed the same Low Coolant signal for no apparent reason. I had recently disconnected the battery to do some work on my stereo so I think in my case it had something to do with the computer resetting the values from the sensors. After a couple of days of driving it stopped displaying the signal. The coolant was never low, and the car never ran hot.
Good Luck
Good Luck
Thread Starter
Burning Brakes
Joined: Apr 2004
Posts: 810
Likes: 1
From: Las Vegas NV
Thanks! I'm giving the Vette time to cool down in the parking lot and I'm going to check the coolant level again. I was most concerned about the overflow tank being filled to the brim.
Team Owner
Joined: Oct 2000
Posts: 96,443
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From: Fort Knox, KY
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Be sure and open the bleed screws on your thermostat housing after your engine cools. It sounds like you may have trapped an air pocket in the line...
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
It overflowed because it boiled over - that can be a radiator cap no longer holding pressure, a stuck thermostat or a blown head gasket. If the temperatures were normal and it didn't run like crap, I'd suspect the radiator cap first.
Thread Starter
Burning Brakes
Joined: Apr 2004
Posts: 810
Likes: 1
From: Las Vegas NV
I took it out for lunch. I checked under the hood. Overflow tank is back to normal...no leaks....low coolant light stopped flashing. I went to the Post Office on the way back and idled the car for about 30 minutes while I was waiting. Coolant temps were normal (200 to 210). Any ideas?
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Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
I'd guess that the thermostat stuck or only partially opened and with the fans being controlled by the ECT Sensor (mounted on the engine and not the radiator), they didn't come on. The coolant expanded and then spilled over into the overflow. If it is the thermostat, it will probably happen again, so you might want to replace it along with a new cap if it's the original.
Le Mans Master
Joined: Mar 2004
Posts: 8,700
Likes: 298
From: Ft. Lauderdale Fl
I agree.....
Originally Posted by SunCr
It overflowed because it boiled over - that can be a radiator cap no longer holding pressure, a stuck thermostat or a blown head gasket. If the temperatures were normal and it didn't run like crap, I'd suspect the radiator cap first.
Drifting
Joined: Apr 2002
Posts: 1,817
Likes: 1
From: Hartland WI
I had a similar problem yesterday - low coolant light coming on and off. Got home and sure enough, the coolant was low (resivor nearly empty). Added coolant this moring and will watch it for a few days. No evidence of any leaks, so I'm not sure where it went. Checked the oil (which was just changed two weeks ago) and it looks fine.
Will probably get a new cap and thermostat this weekend.
What are the "signs" of a head gasket problem? Runs fine, no smoke, plenty of power, no spray in the engine compartment. Should I be worried about that?
Will probably get a new cap and thermostat this weekend.
What are the "signs" of a head gasket problem? Runs fine, no smoke, plenty of power, no spray in the engine compartment. Should I be worried about that?
Thread Starter
Burning Brakes
Joined: Apr 2004
Posts: 810
Likes: 1
From: Las Vegas NV
Well I drove the Vette all weekend. Covered more than 200 miles, no leaks, temperature still normal, no additional "Low Coolant" light indications, no overflow. I idled the Vette in my driveway watched the temperature rise to 228, the fans kicked on and brought the temperatures right back to 200. I've got 46K on the car, oil looks fine...no further trouble noted. I am going to check the bleed screw, replace the t-stat, coolant and radiator cap, even if I get no further indications of trouble just as PM measure. Thanks for the feedback and help.
