How can I replace the water pump on a 2004 Grand Prix GTP superchargered?

Mike LaPres

• 757 Answers
• Posted on Feb 27, 2010

SOURCE: replace thermostat on 2003 grand prix gtp with

The thermostat housing is located in the upper radiator hose. You will see a metal elbow secured by two bolts into what I remember is the upper intake manifold...don't quote me on that but you will see it regardless of whatever I call it. Anyways, GM decided it was a good idea to put stainless steel bolts in there but that makes it easy to strip the threads in the bolt hole so I think it's best when you put your wrench on the bolt to just tap on the handle till you vibrate it loose, then turn it.
When you pull off the housing you'll lose a little coolant and it will create an air pocket which we'll address. It's a 50/50 chance that the thermostat housing gasket will either stick to the housing or the engine...it may be torn, cracked or flaking in either case clean both contact surfaces before you replace the gasket. I recommend an oil impregnated poly material gasket.
Note the position of the thermostat in the hole and place the new one in as such.
I recommend a 180 degree thermostat...stock is 195 but the GTP runs better with the 180.
Put on gasket and reinstall the hose/housing assembly, alternate from one bolt to the other so the housing mates flat and cannot cause a leak.
Next, fill the coolant overflow bottle to the "HOT" mark. If the bottle is dirty and hard to see just put a light on top of the bottle...GM didn't mark it very well so if it's not squeaky clean you can hardly see a damn thing.
*IMPORTANT** if your car still has Dexcool in it, DUMP IT. It will eventually destroy the motor.
If not...continue on. Start the car. Go back to the thermostat housing and place a rag on top of, and twist the peacock valve on top of it to let the air out until it starts to get coolant on the rag. Done.

SOURCE: 2004 Grand Prix GTP (supercharged.)

at normal operating temp your car should run around 200 degrees. the thermostat is what maintains the temp of the engine by opening and closing alowing water to circulate and cool the engine or closed allowing the temp to build up. if the thermostat is stuck open then the coolent is never in the engine long enough to heat up and removes the heat faster than the engine is producing it. A new thermostat is around ten dollars and is simple to replace. Allow the engine to cool all the way down. Get a catch can, take the radiatior cap off and on the bottom right of the radiatior there is a valve, open the valve and drain about a gallon of coolent out. Once you have done this follow your top radiator hose from the radiator to the thermostate housing. There are two bolts one on each side 14 mm remove these bolts and the housing comes up. Remove the thermostate and put the new one in making sure the cone part is up, replace the housing and tighten the bolts. Top off the radiatior with coolent and start the engine leave the cap off and allow the engive to come up to operating temp. once it is warmed up you should be able to rev the engine alittle and see the coolent in the radiator being pulled thru by the water pump. top off the radiator and put the cap back on you are ready to go. after you have drove the car for a few days or ten miles or so let the engine cool down and check the coolent level to make sure its full. air bubbles can get trapped in the system.