coolant light on/off intermidently

[paxton350]

have recently noticed my coolant light coming on and off intermidently. it usually goes off during nightime when it cools down. i dont believe its a head gasket, i mean i would feel a loss of compression/ power, right? i read in my chiltons manual that there is a low coolant sensor, i wonder if this is faulty? should i flush my radiator? or would the water pump be faulty? i mean when im cruising on the highway at about 2000 rpm in the heat of the day about 90* the coolant temp reaches about 220* but when i get off the highway the temp will shoot down to about 190-200. anyone with a similar expirience please help! thanks,

chris

[Sean 94z28]

Have you confirmed that you are actually losing coolant? Or does it still appear full and now you have a light?

The most common cause of the light is an air bubble in the system, usually after a drain and fill. Are you familiar with the bleeding process using the brass screws on the coolant plumbing/therm housing?

Sean

[paxton350]

yes i have plenty of coolant, no im not too familiar with the bleeding process...

-chris

[Sean 94z28]

Try just opening the bleed screws to see if coolant or air comes out. The procedure calls for coolant to be added to the radiator until no more bubbles come out the open bleed screws, then close them. Then run the engine until the therm opens and and bleed again. This is not the way the service manual says to do it (rad cap off), but I have tried that way 3 times (yes I'm that dumb) and it always is a coolant volcano.

Could just be the sensor. Last time my light came on intermitently, I had a small crack in the radiator right near the level sensor.

Good Luck
sean

[Injuneer]

First check the coolant level and bleed the air, as noted in the posts above.

Beyond that, is is VERY common for the LT1's (I think that's what's in the avatar??) to have a problem with the coolant level switch. Cruds up or just plain fails. Its located on the passenger side radiator end tank, a couple inches below the cap. It can sometimes be cleaned.

Helpful hint - add the year of your car to the "signature". Makes it easier for people to give you a correct answer, without guessing.

[TGregg]

Where would one find the bleed screw(s) on a `96 Firebird 5.7L? Are they on the radiator?

I replaced my overflow tank, but didn't bleed the air out, and my coolant light is lit.

[96Camaro]

My low coolant light just kinda stays on now. Even though I bleed the system and there is plenty of coolant in there. I personaly think on my car it is just a faulty sensor or somthing. Maybe its the same for yours too.

[TGregg]

Since I definately put air in the system when I replaced the overflow tank, I should bleed it anyway. Or so I presume. It doesn't sound like it's hard to replace the sensor, either if that is the problem.

[Injuneer]

How did you put air into the system by replacing the overflow tank? If the engine was cold, the radiator would have already pulled in sufficient coolant from the tank to keep it full. When you heat the radiator up, the expanding coolant will be forced back out into the overflow tank, filling the drain tube.

Make sure the drain tube between the radiator and the reservoir has no leaks in it, or you will have air in the radiator.

[TGregg]

How did you put air into the system by replacing the overflow tank? If the engine was cold, the radiator would have already pulled in sufficient coolant from the tank to keep it full. When you heat the radiator up, the expanding coolant will be forced back out into the overflow tank, filling the drain tube.

Make sure the drain tube between the radiator and the reservoir has no leaks in it, or you will have air in the radiator.

Cuz the tank was well shot before I replaced it . I didn't know any better, and would just pour water in the dipstick tube that just went straight to the overflow tank for a few days until the weekend when I could replace it.

And my low coolent light is on all the time. Kevin posted pics to where the bleeder screws are, so I'll try that. If that doesn't solve my coolent light problem, I might try replacing the sensor.

[shadyphi]

Mine comes on everynow and then... faulty sensor... pretty common.

I just don't feel like spending the $$ on a new sensor or tearing into it right now...

Just do a visual inspection everynow and then, until you get around to fixing it the right way....

my 2 cents

[TGregg]

Thanks Bill. Yeah, I'm not worried about the sensor, that's no big deal. Just wanna make sure I've aired out the system. I can always unplug the sensor to shut off the light. Or so I hope. It looks pretty easy to replace tho.

[Disifer]

Mine comes on intermittently on my '94. Usually after the car's heated up and I stop somewhere for a couple of minutes and restart the car. It used to stay on but now it just flickers a few times then goes out.

[lexington01]

My 2000 V6 comes on for about a minute every time I start the car, then doesn't turn on again. I couldn't see the sensor when looking for it (must be in a different place than the V8s per the photos in the guide). I just I'll just live with it...

[paxton350]

i pressure tested my radiator cap and found it was bad.... got a new one and havnt had too many problems with pressure wise.... the light still comes on an off here an there, i might try replacing the sensor...

-chris