Question about 2004 Pontiac Grand Prix

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Problem with 2004 Pontiac Grand Prix 2004 pontiac gp, new heads, gaskets, coolant, oil, thermostat. still spikes heat. what next?

Thanks for answers but let me clarify: I have replaced the heads, head gaskets, thermostat, engine oil and the radiator is less than 6 mos. old. It had blown a head gasket, and cracked heads were discovered so I replaced everything. Sad, I know. Now the engine temp is stable except under these two conditions: 1: When coming off a freeway drive and coming to idle at a stop light the temp will spike after a few and then go back down in a few minutes. 2. When driving on the freeway and then slowing down in traffic the temp will rise and then go down gradually. Strangely, turning on the AC seems to quicken the cool down. So, the entire coolant system has been replaced. What now?

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Replace your coolant temperature switch,it's screwed into block by oil filter.Here's a picture of what it look's like.Your water pump working properly.Are your spark plugs burning clean,not oily from bad piston rings?

Posted on Jan 16, 2013


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SOURCE: 3.8 97 pontiac grand prix engine over heats when

The only next logical step is to have the radiator flushed and cleaned. Over time the radiator slowly builds up deposits along the fins and reduces water flow and heat dissapation. Sometimes Iv'e seen radiators get so full of deposits that only half the radiator is actually working. I have also seen this motor in other GM applications have computer problems and the cooling fans won't run when they should, but when this happens you start to see other funny stuff happening that gets hard to explain till a bad cumputer gets diagnosed. I assume everything else on the engine and car is working fine and your not noticing any other strange behavior from the engine, like hard to start sometimes and other times it starts fine, air conditioning fans work and then they quite and then work again for no apperent reason. If these type things are happening you might want to make sure your computer is working fine, and all the relays are working. Also make sure you do not have any abstructions in front of the radiator blocking air flow. there is also a sensor on top of the plennum that tells the fans to kick on, check this also.

Posted on Nov 17, 2010

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2003 pontiac grand prix over-heating. New water pump, new thermostat, radiators been flushed! Still losing water; cant see where. temp gauge says its hot, but if u turn, it goes back down! Help!

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