I have a 2004 grand prix, 3.8 in need of a thermostat.The engine is not heating up to operation temperature. Where is it located.

It is not the best but can be done.
Don't remove the whole thermostat only the center part and fit the frame back in the housing.
If you remove the whole thermostat you can end up with cavitation problems and this can cause hot spots in the engine.

Don't think so... I had one 2004 prix that lost it's coolant and it ran until it destroyed itself... Had another that would hit red on temp during the summer in the desert mountains. Never shut down on me though.... replaced the radiator, water pump and thermostat. My fans kick on about 3/4 of the temp gauge. Normal temp is between 1/2 & 3/4.

Check the operation of the heater control valve. It will be conected to one of the smaller hoses leading to the heater core from the engine.

On the 3.8 liter the coolant temp sensor is right below the the thermostat in the intake manifold on the drivers side of the engine.

The thermostat is under the housing that is bolted to the intake plenum that the upper hose is attached to.

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TEMPERATURE GAUGE IS MORE LIKELY BROKEN.

It is possible that your thermostat is stuck open. Normally, the thermostat remains closed when starting cold, confining coolant to the engine block and cylinder head until it heats up. Once the coolant in the block is warm (usually within 10 minutes), the thermostat begins to open and let coolant flow into the radiator to cool it down some. A properly operating thermostat will continue to cycle until the coolant reaches the operating temperature of the thermostat--usually around 180 deg F. Then the thermostat will continue to adjust its opening to maintain that temp.

Thermostats can get stuck in both closed and open positions. When stuck closed, the engine will quickly overheat. When stuck open, the engine will take forever to warm up--especially in cold weather because the coolant is continually pushed into the radiator and cooled off before it ever has a chance to get warm. Changing the inexpensive thermostat may help correct your condition.

If engine temp is warm, then either your heater core is clogged and needs flushed or your warm /cold door motor is not working properly(located under the dash). if you engine si not getting warm you have a bad thermostat.


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I suspect you have a bad fan relay or temperature sensor. Here's a link to a page where you can see what these parts look like. The fan relay is usually located in the engine compartment inside a plastic box with a removable lid. It just plugs in and out. The temperature sensor will screw into your engine block and have a cable connected to it. Your owner's manual may give you their exact locations. http://www.diypartscatalog.com/ShopByVehicle.epc?q=2004-PONTIAC-Grand--Prix-V6--31ci--3.8l--F/i--Vin---Belts/hoses/cooling&yearid=2004%40%402004&makeid=67%40%40PONTIAC%40%40B&modelid=13463%40%40GRAND+PRIX&engineid=30226%40%40V6%2D231ci+3%2E8L+F%2FI+Vin+2%40%4030226&catid=2%40%40Belts%2FHoses%2FCooling&subcatid=36@@Sensors%2C+Switches+and+Relays&mode=PA

You might have a thermostat stuck open this will not allow the coolant to reach correct operating temperature.

i dont think it needs a waterpump. what temperature thermostat did you put in? unless the fan is running all the time maybe. i would try another thermostat, the engine needs to be at least 195 degrees to produce decent heat.