Pontiac Grand Am Overheats

overheating
coolant
pontiac
grandam

#1

I have a 2004 Grand Am that I was driving once a few months ago and it overheated. I immediately pulled over and shut it off. I got out and looked under the hood but there was no steam and no apparent leaks. After a while I started it up and it was normal temp. I drove it home and the next day had it towed into a shop.

They said I needed a new thermostat and water pump. Reasonable. So I got it back and it was fine for a while but then started overheating after about 10 minutes driving. But a lot of the time, it would cool off after only a few seconds. This went on for a bit and I took it back to the shop. They topped off the coolant and told me the heater core needed to be flushed, but that they didn’t do that.

So after another couple of weeks of this I called around and found a shop to take it to. They said “Oh no, that is not why it is overheating, bring it in for a second opinion.” So I took it in and they did a full flush and refill of coolant.

SAME THING. Also - the heat blows ice cold if I am idling or running at low RPMs. Also it takes at LEAST 20 minutes of driving for it to even try to blow warm air. I am getting really tired of paying mechanics to not fix this! Over $1000.00 so far! :frowning:

HELP please!!

EDIT TO ADD: Full disclosure. A few months ago the security system started to fail so I had the computer core replaced with an exact duplicate that had been code altered to remove the security check. I had to do this because it would randomly decide not to start because it thought I was trying to steal it. I had to do the reset dance with the keys every time I wanted to drive somewhere which took 10 minutes of sitting there looking like a moron in the car.


#2

Have you had the coolant temperature sending unit checked? If the car cools off after “only a few seconds,” then I would think that there might be something faulty with your temperature gauge or the sending unit, or the wiring in between.

(But this might just be on my mind because I’m fixing a temperature gauge problem on my car. It could be something else, and I’m sure some more experienced mechanic will come along with a good answer.)


#3

I’m thinking the cooling system has air in it. An air bubble in the heater core will cause circulation problems and the heater will not warm up. An air bubble will also cause overheating problems as a sizable air bubble will delay the thermostat opening.

As to why an air bubble is in the cooling system may be due to a head gssket issue. I didn’t want to say that, but it needed to be said. A way to check is to remove the radiator cap with the engine cold. Make sure it is full by adding coolant if you must. Then, start the engine and watch the coolant. If air bubbles start to rise, have the coolant checked for HC contamination. HCs in the coolant is a sign of a head gasket problem.


#4

I agree with the air in the cooling system. Hopefully its just trapped from when they flushed the system. Loosen the cap and see if the air works out


#5

I don’t think it has a radiator cap. I think it has air. You can stick

GM Procedure
4 cylinder
Fill the cooling system.
Slowly add a mixture of 50/50 DEX-COOL and clean, drinkable water. Important: It is necessary to maintain the coolant level at the top of the surge tank label to insure all the air has been purged from the cooling system.
Install surge tank cap.
Start the engine.
Run the engine at 2,000 - 2,500 RPM until engine reaches normal operating temperature.
Allow the engine to idle for 3 minutes.
Shut the engine off.
Allow the engine to cool.
Top off the coolant as necessary.

6 Cylinder
Open the cooling system bleeder screws Important: Open the cooling system bleeder screws.
Slowly fill the cooling system with a 50/50 coolant mixture.
Close the cooling system bleeder screws.
Install the coolant pressure cap.
Start the engine.
Run the engine at 2,000 - 2,500 RPM until the engine reaches normal operating temperature.
Allow the engine to idle for 3 minutes.
Shut the engine off.
Allow the engine to cool.
Top off the coolant as necessary.


#6

Could definitely be air remaining in the cooling system, and that could cause this symptom. That’s the first priority I think. If it turns out not to be that, remove the thermostat and test it by placing it in a pot of water which you heat up on the stove, and a thermometer measuring the temp. Check that the thermostat opens fully to the dimension it should (find the spec), and at the correct temperature, and when cold it returns to home fully closed. Also compare it to the original one that came with the car if possible, there are mechanical differences in t-stats and maybe the one installed is not the correct one for your car. Thermostats have to be installed in the correct orientation, front vs reverse, and up and down, that’s another thing to check.


#7

The problem is related to the computer sending a ground signal to the cooling fans. I just fixed my daughter’s 2003 Grand Am GT. The problem is what looks like a relay mounted to the driver’s side fender wall. It’s located directly across from the air filter assembly. Pontiac has located this device there and all your major grounds join here. The mounting plate attached to it becomes corroded which interferes with the grounding signal from the computer to turn on the cooling fans. The bolt that held it in place was actually so rusty that the head of the bolt had broken off as I removed it. I used a circular wire brush attached to my drill to remove the corrosion from the back plate. Used the same brush to create a new bear metal spot on the fender and a self taping screw to reattach it. No more over heating from there on, Fans triggered and varied speed as they should.
Also check the O-ring is still in place on the coolant reservoir cap, it cracks and falls off.


#8

Thanks for the info Richard. But if theOP hasn’t fixed the problem in the last 5 years I doubt the car is even still on the road. Still it just may help some one.:+1:


#9

if you want to help @GooberGrape, click on his avatar. Then you’ll have the opportunity to send him a private message. Otherwise, he probably won’t become aware of your solution