Thread: '04 Grand prix GTP problem galore

Hello everyone i am knew to this forum, and after 3 months of GTP problems i finally thought it was time to try out a forum. I own a 2004 Grand Prix GTP v6 supercharged 3800 competition series. It just tacked 150,000 and our battery had fried out, so i bought a new battery and this is when everything went downhill. The car would now start, but whenever i turned the A/C power control to full, it would continuously blow out air even when the car is off key out of ignition. First my mechanic thought it was a ECU Problem, so we found one an switched it out, didnt help anything. We than found out that we needed a new A/C control deck. Switching that out another problem occurs an my ABS unit needed to be replaced because it was currently shut down along with the Traction control, we fixed that next and i was hoping this was the end of my problems. Once again it wasnt, The day i took it out for a test drive, the thing overheats an shuts its self down on the side of the road getting a message saying "A/C shut off for engine protection," which is normal of course for overheating problems. We figured out that i had left over water in the coolant system from the summer which had froze on a 0 degree night, whoops thats all my fault but an easy fix to say the least. We drained the system, re filled it with coolant, bled the air out and gave her an oil change while we were there. Theres no water or coolant leaking into the oil its not frothy or bubbly, clean oil on the dip stick. Next day the car started to overheat again, The heat motor starts to grind when i switch it from A/C to heat, and the car is now having a rough idle along with overheating after 10 mins of driving. I now am starting to think i have a blown intake manifold gasket? Any help would be great.

Where are you in NH? I'm not the world's biggest expert on these things, but I know some stuff and maybe we could meet up somewhere

The A/c motor doesnt grind, only when i switch it to heat an on, it was diluted coolant, and pelham nh, the rough idle started only after we drained coolant/water mix refilled and burped the air out. RPMS dont drop in the idle, just it seems there some wierd shaking occuring

My mechanic said theres several factors, either a leaking intake manifold, junk thermostat an waterpump, or radiator. we just replaced a valve manifold due to leaking oil onto the headers. Would also like to add when the temp guage boosts up all the way to spiked, itll occasionally drop down to the bottom of the red zone, and then jump to the top again

Originally Posted by Jkeighs

pelham nh,

I drive down Rt. 495S every day. I generally pass through the Lowell/Dracut area around 6pm-6:30pm. Let me know if you'd like me to stop in some evening after work.

-Bob C.

I would have to ask my father first sir, as i am just 19 an the owner of this car but i will definitely let you know cause were pretty stumped. The overheating didnt occur until the diluted coolant froze, and was then emptied out and refilled + air burped. the stuttering idle also didnt occur until this happened.

would also like to add that the rough idle only lasts for about 4 seconds after it turns over, Itll have some terrifying knocks for 4 seconds and then it turns into ticking or a noise like a belt is worn out almost.

Here you go man

Fans are running fine, i just took the radiator cap off and it burped out coolant, which either means theres air leak in the cap or somewhere in the system. Or the shop i brought it to that apparently bled the system didnt get all the air out. i will try bleeding it myself and see the results.

Wouldnt a blown head gasket make it so the oil was milky or frothy though?

Well its getting later so ill test that tomorrow, thank you for the advice and ill definetely be back to tell you how it goes.