2000 Grand prix coolant light low???

OKay 3.8 Liter, 71k miles. Everytime I start the engine cold the low coolant light is on until driving for about 10-15 minutes. Goes off stays off until engine cools down. I have checked the radiator and verified the coolant is a cup or 2 low. I usually drain the coolant back into the radiator from the overflow bottle which never gets low or anything but will always be at the same mark. So it seems the radiator will expel the coolant back to the overflow bottle when it heats up but doesn't suck enough back in when the engine cools down? thus causing the light to go on and off. So why?

Check and make sure that the tube running to the coolant bottle isn't partially blocked. Sometimes the coolant will deteriorate the tubing and will only let coolant flow one way. Second, your radiator cap may be at fault. If it doesn't hold as the engine cools it will not allow the system to create a vacuum to draw the coolant back into the radiator. Finally, check to make sure that the hose inside the coolant tank is connected and that there no holes in it. This too can cause the system not to draw the coolant back into the radiator.

Thanks for quick reply. I was able to blow throught the hose no problem. 2nd there is no hose inside these bottles. 3rd I will try a new cap. Thanks

I would say your water pump is going out.....what are you temps running at?

Have you bleed the air out of the system???......that could be your problem.Get the car to operating temp with the cap off then top off the radiator put the cap back on then make sure the bottle has colant in it then bleed the system.....~Larry~

Well I let the engine heat up and I have been opening the bleeder on the thermostat. The temperatures on the highway run right on the 1/4 line and a bit higher on the highway. Could my problem be a cracked intake manifold? I don't think a headgasket is a factor as my fluid doesn't lose or no tailpipe smoke. I bought a cap and gonna try that today.

If you have a cracked intake then you would be getting water in the oil....also you would have a vacuum leak and it would not run very good..do you have any leaks under the car from coolant??There is a weep hole under the shaft of the water pump that will leak coolant once the bushing goes out...~Larry~

I have a 99 GT with 98k on it and my reservior loses about a cup of coolant every two weeks. The low coolant light flashes and I add colant and the light goes off. I see NO LEAKS anywhere. Doesn't run hot. I was thinking about changing the thermo, cleaning out the reservior and the line going to the radiator and flushing the system. Do you think this would solve my problem? Thanks.

I have a 99 GT with 98k on it and my reservior loses about a cup of coolant every two weeks. The low coolant light flashes and I add colant and the light goes off. I see NO LEAKS anywhere. Doesn't run hot. I was thinking about changing the thermo, cleaning out the reservior and the line going to the radiator and flushing the system. Do you think this would solve my problem? Thanks.


Hi, I had same problem with My 2000 Grand Prix GTP, The Low Coolant light was coming on every 10 to 15 minutes. I took to the dealer and replaced the Coolant sensor. The sensor was leaking the and causing the problem to light come on the Dash. After replacing the Coolant sensor, everything works fine now. I paid almost $282. Which include diagnostic check,coolant and rediator flush. I have only 42,000 miles on my car. Since then my car is running perfect and the gas milage is about 19.0 MPG in city. Which is very good.

its hard to say what it could be, but I know with the GM 3.1, 3.4, and 3.8L engines one of the most common issues it has is that the intake manifold gasket deteriorates and begins to leak. I have seen them fail on cars with 15,000 miles, but that causes it to leak oil, not coolant.

i have a 1998 Grand Prix GT. After 20 minutes of driving the tempeture climbs to 100 at idle..is this normal?

OKay 3.8 Liter, 71k miles. Everytime I start the engine cold the low coolant light is on until driving for about 10-15 minutes. Goes off stays off until engine cools down. I have checked the radiator and verified the coolant is a cup or 2 low. I usually drain the coolant back into the radiator from the overflow bottle which never gets low or anything but will always be at the same mark. So it seems the radiator will expel the coolant back to the overflow bottle when it heats up but doesn't suck enough back in when the engine cools down? thus causing the light to go on and off. So why?


Are you loosing ant coolant? If you are cheak you oil and manke sure it isn't going in the crankcase. The Plantum on the 3800 engine will melt where the EGR valve tube goes and allow colant to go into the crankcase or the intake. If this has happen to you car replace the intake ASAP, you might want to also replace the crank and rod bearings also. I have replaced several of the plantums and latter had the rod bearing go out.

Hi, I had same problem with My 2000 Grand Prix GTP, The Low Coolant light was coming on every 10 to 15 minutes. I took to the dealer and replaced the Coolant sensor. The sensor was leaking the and causing the problem to light come on the Dash. After replacing the Coolant sensor, everything works fine now. I paid almost $282. Which include diagnostic check,coolant and rediator flush. I have only 42,000 miles on my car. Since then my car is running perfect and the gas milage is about 19.0 MPG in city. Which is very good.


I get about 21.4 MPG city, and that's with me raising hell in my car.