I have a strange low coolant problem. This just started. When Cold from sitting overnight the low coolant light comes on first thing in the morning. When i drive to work (4 Miles) it goes off on the way. Then after working all day i get in the car and its still fine. It seems to be after sitting all night. Now I replaced the rad hoses, hose from rad to overflow bottle, new clamps even new rad. I burped that rad and filled the overfill to the cool line. When the light does come on i can take the exact amount in the bottle and refill the rad. I can see no leeks. Car runs cool. dont over heats. no water in oil or oil in water.
Also has new rad cap.
And like i said only does it after sitting at night.
I dont have a pressure tester.

Any Ideas..

Donnie

 

Year Vette would help...

If you're having to constantly refill the radiator and the overflow tank, your engine could have a Head Gasket leak.

A head gasket leak will suck in coolant and get burned in the combustion chamber along with the air and fuel. The engine won't show any external coolant leaks.

 

Looks like he has an 86.

A coolant loss thru a head gasket could result in white smoke (steam) from the exhaust and some amount of condensation each morning. Do you see anything like that?

Chain parts stores like AutoZone "rents" tools like a cooling system pressure tester at no cost. Go to the store, ask for a pressure tester and you pay a deposit. When you bring the tool back in good condition, you get your deposit back.

It's possible that burping the system didn't work well. When the engine is cold (in the morning), where is the coolant level in the radiator? Remove the cap before starting the engine.

Try the burping process again. With a cold (or cool) engine, raise the front of the car at least 12". Remove the cap and start the engine and let it idle. Watch the coolant level when the thermostat begins to open. The level should drop. Raise the engine RPM to around 1100-1200 and start adding coolant to the radiator and fill to the base of the neck. Replace the cap, shut the engine off, and lower the car. Add coolant to the HOT line of the coolant recovery bottle.

Drive around during the day and the next morning, check the coolant level again. Let us know what you found.

 

Looks like he has an 86.

Yep its an 86.

A coolant loss thru a head gasket could result in white smoke (steam) from the exhaust and some amount of condensation each morning. Do you see anything like that?

No smoke cold or hot.

Chain parts stores like AutoZone "rents" tools like a cooling system pressure tester at no cost. Go to the store, ask for a pressure tester and you pay a deposit. When you bring the tool back in good condition, you get your deposit back.

It's possible that burping the system didn't work well. When the engine is cold (in the morning), where is the coolant level in the radiator? Remove the cap before starting the engine.

Try the burping process again. With a cold (or cool) engine, raise the front of the car at least 12". Remove the cap and start the engine and let it idle. Watch the coolant level when the thermostat begins to open. The level should drop. Raise the engine RPM to around 1100-1200 and start adding coolant to the radiator and fill to the base of the neck. Replace the cap, shut the engine off, and lower the car. Add coolant to the HOT line of the coolant recovery bottle.

Ok will try that. The coolant level drops a little when the thermostat opens. When it was cold it just touched the sensor when it wasnt running. no bubbles in the coolant when the car was running. just dont think it is lossing it. Will also look at the oil cooler to see if maybe a bad hose..


Thanks,
Donnie

Drive around during the day and the next morning, check the coolant level again. Let us know what you found.[/QUOTE]

 

If the cold coolant level is just at the sensor, the Low Coolant light will come on once the 'stat begins to open. Fill the radiator to the bottom of the filler neck and see what happens. Hopefully it's just an air pocket that burping can get rid of.

If the cooling system is working properly, the coolant level will always be right at the filler neck.

 

I fill it before i go to work. It sits all day and when i get home its sill good. what is strage its only after sitting all night, but good when sitting all day. i use a turkey baster to take it out the overflow to put in the rad. takes the same amount everyday. I ust jacked it up and run it till the thermostat open. ran it up to 2000 rmp and filled it to the top. put the new cap on then rop the car to 650 rpm and lowered the car. Will check it in the morning and see if its low.

 

it sounds as though you never got it full. however as it cools off it should suck coolant from the overflow bottle into the radiator. it will not do this if you have a leak anywhere in the system, even a small pin hole will allow it to suck air in to fill the void created by the cooling water. check all of your clamps again to ensure that they are water and air tight if you still have issues.

 

Will try that. I just jacked the front of the car up and did it again. Will see in the morning. Its driving me nuts.

 

Try this,

Each, morning top off the radiator coolant with water from a bottle, not from the coolant reservoir.

If you find you have to top off the radiator each day, the engine probably has a Head Gasket leak.

 

Well i Burped it yesterday afternoon and this morning it seemed fine. The coolant level was still on COLD mark. Drove it for a few miles and no light come on. Iam hoping this fixed it. Will know better in the next few days. Will keep ya posted.

 

You can have this problem if the radiator cap is the wrong one for your car.

The water from the overflow tank should get sucked back into the radiator when the system cools off. A bad/wrong radiator cap will prevent this from happening.

 

Well its been 6 days and no more low coolant light on. Another new rad cap (Number 3) and reburped it seem to have fixed it..