Thread: Heater Problems 2004 Grand Prix

I have a 2004 grand prix 3.8l. I have always had the problem of air in the coolant where you can hear it sloshing around in the heater core under the dash. I have never been able to bleed the system right or ot just doesnt fix the problem. But anyways, my heater has jusr started giving me problems. It took a half hour for it to start blowing hot air,and now it only blows cold air constantly. I tried bleeding the coolant but now all it does is blow out hot steam or air, no coolant will come out now. So i changed the thermostat since my coolant isnt circulating but that didnt fix it and now my cat overheats. So now im thinkimg my heater core is clogged or radiator. Also my top radiator hose gets hot and bottom hose is barely even warm. Oh and also, yes i have had the engine at operating temp when bleeding it and the radiator and overflow tank are full of 50 50. I am guessing my heater core has clogged up from having air in the system for so long. Has anyone else had this problem? Are the heater cores on these cars very difficult to change. Any help would be greatly appreciated! Thanks so much.

take the heater core lines off the engine by the alt, then put a garden hose to one hose, turn it on till water flows out the other hose, then switch hoses, aka back flush the care, then put the hoses back on the engine. try to keep the hoses full of water when putting them back on.

I had the same issue when I got my car originally. back flushed the heater core 3x's and had dime size chunks of debris flying out. made a huge difference I agree with Scotty... backflush before spending more money

But you will want a 2 liter bottle or milk jug that way you don't spray sh*t all over

they just flush the engine and rad, chances are they wont touch the heater core.

heres how i flush coolant. its rather easy to do can be done in less then a hour if taking your time. and using a flush agent.( you would be flushing 2 times.





remove the t stat, put the t stat housing back on, take the upper hose off the radiator, then push it down to the ground to a bucket or let it fly.


get your garden hose out, put it in the rad turn it on, then fire up the car, let it run till clear water pumps out the top hose.


then turn the hose off, run the car till no more water comes out the upper hose. then turn it off.


put your t stat back in, with new gasket, the upper hose back on.


now take 1 gallon of full strength green antifreeze, not the 50/50 crap. ( parts store cheap green is fine to use) dump the whole gallon in the radiator, fire up the car, fill the rad with hose water till its full. top as needed till its ready to be bled of air. it will burp and take coolant as the water in the block warms up the t stat opens up for a few seconds till cold coolant hits it and it shuts again.


now to bleed the air out, let it idle rad cap off till the fans turn on, (when the fans are on the temp is over 195 deg, the t stat is wide open) then open the bleeder screw on top the t stat housing a few turns till a steady stream of coolant comes out the hole, shut the screw, top off the rad. cap it.


done.

Are they flushing it for you as well? If they are then you have them put in whatever coolant you want (I like green) if they aren't flushing it and your going to do that yourself have them just throw in Dexcool. Then do it yourself and flush with green.

water pump and tensioner are less then 60 in parts and a hour of your time. ouch. i hate shops.

green coolant is fine to use. your car came with the orage crap thats causing your sludge like boogers in the t stat and the rad cap, and everywhere else. this is why we change to the green coolant.

your cooling system holds roughly 3 gallons, so one gallon of full strenth coolant will keep your safe down to -20 iirc.

i buy the full strength vs the pre mixed, why pay for 3 jugs at 14 bucks a gallon when you can buy one gallon for 12 bucks,(store brand cheap stuff)

I would just do the labor yourself. Will take you a hour tops.

me too. big time. pay them for the diagnosis, and do it your self. then your have a 120 bucks more to spend on x mass lol


water pups run 40 bucks, it comes with a gasket if you want some pics and a how to just ask, water pump is super easy.

the tensioner runs around 20 to 40 depending on which one went bad. super charger one is like 20 ish the other one by the alt costs a bit more.

the new t stat gasket is 2 bucks the new coolant is 14 bucks tops.

you could do the pump then flush it. you know the shop wants another 50 or 60 to do the flush.

Just about everything besides the trans is very easy to do and requires little work and only basic tools.

i just put this new exhaust pipe on in the rain, outside on a sheet of ply wood lol. life goes on........i was quoted last year 350 for a new cat back, its all changed now, didnt cost anywhere near that quote. granted it was done piece by piece over the last year, but its all new now.