Engine Overheating('99 3100)

I have a 1999 Grand prix with the 3.1.I changed the thermostat and put new gm coolant in(the orange stuff)it still overheats.when you start the car it will overheat and eventually it'll cool down and blow hot air but then eventually it'll get hot again and blow cold air.I was just wondering if anyone has had this problem before or know of what it could be?I'm thinking i need to do a radiator flush or i have a leak somewhere but if you think it could be something else please help.Thanks

ok, lets back up here, did you bleed the air from the system after you put the new t-stat it?

In addition to tblake's question, was it doing this prior to the t-stat replacement or only afterward? Have you been losing coolant with no external leaks?

Yes it was doing it before i replaced the thermostat.I bleed out all the air.If im losing coolant its not much at a time(i'm driving my other car till i figure this out so i dont ruin the engine)also i can smell coolant when it starts to get hot im not sure if its from the blower or the engine bay.Thanks for your help its confusing me lol

The GM 3.1 is known for intake gasket issues. It will start out as a slow drop in coolant level and will cause your symptoms. Check your oil and see if it is overfull, or looks cloudy/murky. If so, then it's time for an intake gasket replacement. They will often seep externally along the seam between the intake and the block/heads as well, so take a look and see if you see anything. If this is your issue, get it taken care of ASAP, as the diluted oil will cause cam/lifter/main/rod bearing failure, as well as running it hot can/will blow a head gasket.

The GM 3.1 is known for intake gasket issues. It will start out as a slow drop in coolant level and will cause your symptoms. Check your oil and see if it is overfull, or looks cloudy/murky. If so, then it's time for an intake gasket replacement. They will often seep externally along the seam between the intake and the block/heads as well, so take a look and see if you see anything. If this is your issue, get it taken care of ASAP, as the diluted oil will cause cam/lifter/main/rod bearing failure, as well as running it hot can/will blow a head gasket.

i would have to say a head gasket....just my :2cents:

we all know 3.1's are known for them

i would have to say a head gasket....just my :2cents:

we all know 3.1's are known for them

Yes, thats what I initially thought too, but got to rule out the basics before he dives into a head gasket.

Plus the 3100's usually only have head gasket problems because of overheating caused by lower intake gasket leaks.

:werd: Tim. If you catch them early, you can just do the intake gaskets and you're done. If you've ever overheated one to the point where the car stalls, the head gaskets are done as grandprixgtx00 mentioned.