Overheat

[Paul]

2005 Grand Prix GT 3.8 ltr 6 cyl.
Heater blows cold. Needle climbs to middle of guage or slightly higher at idle . Cools when driving city or highway speeds. Checked and topped off reservoir.
Any help? Anything common with the grand prix? Plastic intake manifold?

Topic

[Daniel]

There have been alot of issues with those intake manifolds cracking. It sounds like you may just have a bad thermostat. I don’t know if your car has one of those valves that controls the coolant flow to the heater core but, if so I would check the connections to that too.

[Mike]

if it stays cool on highway driving, it is usually not a thermo issue. Are you losing coolant? Did you check to see if you have air in the system?

[Jim]

Just did an intake gasket on one of these the other day. Look around were the belt tensioner is. Is there wetness or orange crust? That is a sign of a intake leak or those plastic elbows broken. As for checking the coolant, make sure u open the radiator cap and look at the coolant level in there too. The resivour is only an expansion tank for the excess coolant when the car is warm. Hope this helps. Let me know if you have any questions .

[Daniel]

Well he said when it idles it goes up to half way or a bit higher (which would be normal) but then it goes down when he is highway driving, which could be the thermostat if the thermostat is stuck open.

[Paul]

Thanks, I’ll check first thing in the morning. I was told the intake manifolds have ends that ” melt”.

[Paul]

It has always had the needle below middle for the life of the car. I noticed the transmission temp has been 220-290 which is higher than normal as well.

[Paul]

Had the water pump go out 6 months ago. Replaced by local garage, promised it was an OEM pump not Chinese. I’ll check around the tensioner first thing in the morning,
Thanks

[Paul]

Haven’t checked for air and don’t see any leaks but haven’t done pressure test.

[dreamer2355]

Here is a video Eric made on over heats. It covers some good points.

Let us know what you find.

[Charles]

Check the coolant in the radiator ( check the radiator hoses for pressure first). Your car dosen’t have a pressurized reservoir and depends on vaccum to pull coolant back into the radiator. If you have a coolant (air) leak, the coolant will not be replenished from the reservoir. So, even though the reservoir may be full, the radiator may be low.

[EricTheCarGuy]

I strongly recommend checking for air in the cooling system first thing.

[Author]

Replies