Update: '05 grand prix getting hot

[volk06]

Well I installed the thermostat and that did no good but have noticed the following. When the temp gauge reaches the red, if I turn the heater on while driving, the heater will blow out HOT air to the point to where you cant hold your hand in front of it. After about a minute of this the temp gauge will drop like a rock to where it should be. However, when I come up to a stop light for more than 30 seconds, my heater air turns luke warm the temp starts going way back up.

So in short driving with heater on = normal temp and hot air. Driving with heater on and sitting still = high temp and cool heater air.

Ideas?

 

[71Chevyguy]

I had an issue like this with a Grand Prix before and it actually ended up being the gauge itself that was way off. If you have access to someone with a computer trouble code scanner than can do real time information then you can see if the car is actually running that hot or not. I had a ton of complaints about that one car and it ended up being the gauge itself. Not saying this is your problem but just be aware that it can happen. Most of those dash gauges are way off or totally useless. Also sounds like you may have some air in the system. If it is a series 2 3800 then you may be having manifold issues. They are known for that and it is not a difficult fix. The series 3 3800 resolved many of those issues by going to an aluminum manifold as opposed to the plastic one. Not sure if it was 05 or 06 that they went to series 3.

 

[volk06]

I have a series 3 engine, I think they went to that in 2004.

I'm also installing a new cap on the system tonight.

 

[Chris142]

Originally Posted By: volk06


So in short driving with heater on = normal temp and hot air. Driving with heater on and sitting still = high temp and cool heater air.

Ideas?
Did you open the bleeder screw when you refilled it? It sounds like it either has air in the system or the WP impellers are rusted off.

 

[mechanicx]

What you describe sounds like there could be an air pocket. I think the heater in these cars is in a high spot so the air could be collecting there at idle. There is a bleeder I believe at the T-stat housing, but if you run the engine at fast idle, with the cap off and heater on max till t-stat opens this should get all the air out. Did you do this? I was going to ask if any work had been done at the waterpump and could it be possible your heater hoses are reversed, but since your heater works so well I doubt that.

 

[ddean]

I know that the gauges on the final Grand Ams and Aleros are not the best as well. Also does the 3800 Series III engine have coolant bleeder screws? This was a problem on the 3100/3400 engines where someone would let the coolant get low and never bleed the air out of the system. Then overheating would occur because of the trapped air bubble.

 

[volk06]

I did not run it with my cap off. I'll do that when I put the new cap on.

Also now when I come to think of it, when i turned my air on i heard a gurgling noise.

 

[mechanicx]

Sounds like you have every symptom of air in the system. Run it with heater on max at a fast idle with the cap off until the T-stat opens. Some coolant will probably spill out the radiator but not too much. Once the top hoses is hot you can put the cap on to the first "click" or even all the way once you see the air pocket escape.

 

[Chris142]

Originally Posted By: volk06


Also now when I come to think of it, when i turned my air on i heard a gurgling noise.
It has an air bubble in it. If you don't open the bleeder you wont ever get it out.

 

[Warstud]

Did you fill the radiator back up after installing the new t-stat?

 

[volk06]

I hardly lost any but yes I did.

 

[volk06]

I was paying close attention while letting it idle for a long time getting the air out of my system.
I put a new cap on and and followed the procedure with my cap off. After it start spurting out and the themostat opened I shut the car off and opened the bleeder screw. Before I opened the bleeder screw I let the car run a bit more and the temp gauge started to rise again. I looked under the hood and the hoses were collapsed! So then I shut it off and cracked the bleeder. There was quite a bit of air in it yet and i could see air bubbles coming out. After I bled it for about 5 mins and nothing more happened I tighted the screw. Took it out and let it idle and the temp gauge never got above half!
I think we have solved the problem, air in the system! Could have been the problem the whole time.

 

[Drew99GT]

If you leave the bleeder screw open as the car cools, it'll simply suck air back in. The way to do it is, open the bleeder before you do anything. When you refill the system, as soon as coolant starts flowing out the bleeder, tighten it and top the system off.

Also, fill the system with the heater on so air will purge from the heater core.

 

[mechanicx]

Glad you got it fixed. As Drew said that bleeder is for just when you are filling the system cold and engine off. You still would've needed to do the procedure of running till t-stat opened. If you'll notice the bleeder is on topof the t-stat housing and just upstream of the thermostat so once the t-stat opens the bleeder is redundant anyway.

 

[volk06]

Originally Posted By: Drew99GT
If you leave the bleeder screw open as the car cools, it'll simply suck air back in. The way to do it is, open the bleeder before you do anything. When you refill the system, as soon as coolant starts flowing out the bleeder, tighten it and top the system off.

Also, fill the system with the heater on so air will purge from the heater core.

I shut the car off to crack the bleeder just so I would reduce the chance of burning myself in case coolant came out. Once I cracked it I let the car run for a while and when I stopped seeing air bubbles and sputtering and had a constant flow I closed the bleeder and refilled. The heater was on blast the whole time.

 

[mechtech2]

The water pump is not circulating coolant at idle very much.
This is normal, to some degree. This kinda explains the situation.
But you may have a bad impeller [loose or corroded] on you WP.
It is a tough diagnosis.

 

[Merkava_4]

On mine, I just bleed the air out through the reservoir tank.
As the coolant is getting sucked into the radiator from the
reservoir tank, big gulps of bubbles will go into the reservoir
tank from the opposite direction. You just gotta be there
standing by with the coolant bottle and add coolant as the
level goes down in the reservoir tank.