GP overheats at idle

[Phoenix69]

Hey guys, i've been having problems with my 97 grand prix GT overheating at idle. The temp seems to swing very quickly, perhaps traveling the entire spectrum in 10 or so seconds while driving/stopping at a stop sign. Just recently, when i am driving the car, the temperature is dead center. When i idle, usually at a redlight, my car will overheat very quickly and the temp warning lights ect will appear. I also have no heat in my car, only cold air comes out. I believe this is due to the previous owner of my car never flushing the coolant in the 8 year time span she had the car for. I have had the thermostat replaced recently and still have the problem. I have flushed the coolant twice at a dealership but im not entirely sure on the quality of a flush they performed. Any ideas? Thanks.

[corning_d3]

That sounds like either air in the system, or a bad waterpump.

[richtazz]

You need to determine if your fans are coming on and coolant is circulating. If yes to both, then you have either air in the system or a blocked radiator. If not, check the fan relay and coolant temp sensor that turn on the engine cooling fans. If the coolant isn't moving through the radiator, then it is either blocked or the water pump impeller may have come off causing no coolant circulation(no external leaks would be present). You may also have an upper plenum leak, very common on these cars, that is causing you to lose coolant, and thus no heat. The heater core is one of the highest points in the cooling system, and is one of the first to get an air pocket trapped in it when the coolant gets low. Get the intake checked immediately, as it can cause the engine to hydrolock (coolant fills the cylinder(s), and can't be compressed like air), causing extensive engine damage like bent connecting rods and broken cranks.

[Phoenix69]

No, my car is not leaking coolant. I hear a sloshing noise though as i accelerate. It is perhaps the most bizarre noise i have ever heard in my life. Still not entirely sure what that is or how to remedy it.

[Phoenix69]

Also, is it very bad for me to continue to drive my car with the condition it is in?

[richtazz]

I would advise against driving it, you could do extensive damage if it overheats.

[BIG-L]

I hear a sloshing noise though as i accelerate. It is perhaps the most bizarre noise i have ever heard in my life.

Sounds as if you may have water in the heater box.

[corning_d3]

Mine makes that sloshing sound when air has gotten into the system.. It's air bubbling thru the heater core..

[kustomkid54]

That's what iot sounds like to me.

Originally Posted by BIG-L

Sounds as if you may have water in the heater box.

[ericn1300]

Back to basic guys. First check to see if the the coolant level is low. If it is you have a leak or bad radiator cap. Leaks can usualy be found by visual inspection, a pressure test may be needed to assist you in finding small leaks.

If the coolant level is correct and your vehicle overheats at speed, you have a coolant flow problem. If your car overheats at idle you have an air flow problem.

Have you checked the coolant level yet? Check it at the radiator cap opening when the engine is cold. It should be no more than an inch below the opening.

[Phoenix69]

I have had my coolant flushed twice. The mechanics said that what came out what horrible. I still have very little heat in my car, an overheating engine problem, and a sloshing noise (assumed it was air pockets). Should i personally flush the system and spend a very long time on it? If not, what would my best options be?

[richtazz]

If you are losing coolant, even slightly, you may have the infamous intake plenum leak. You need to have the cooling system pressure tested, as that will determine if there is a leak that is allowing air into the system. No other diagnosis can be done until we determine if the cooling system will hold pressure.