95 Grand Prix Overheating

I have a 1995 grand prix SE coupe. It just started overheating recently. ive had the car for about 3 months now, when i bought the car it had a bad heater core and i knew that, i replaced that promptly. and its been fine untill about a week ago. I just took it in and had the thermostat replaced, and still no luck :( . ive been told it could be the
head(s) or the head gaskets.its full on fluid with a 50/50 mixture. it also started making a loud scraping metal sound from the engine. sounded like it was comming from the water pump. alot of miles on the 3.1, 214k engine runs very strong car has alot of power to it. i checked for milky oil and there isnt any, i cant smell any antifreeze anywhere, but its getting air in the cooling system from somewhere, there are bubbles comming up into the coolant tank when its running, when i squeeze the coolant hose from the radiator to the thermostat\engine bubbles are blown into my coolant tank. ive bled the coolant system of air, but it keeps getting air in the system. coolant is also quite dirty. ive been told its probably the heads going out, blowing exhaust into the coolant. i just want some input so i can be sure before i take it in to have the heads replaced.

Any advice\help is appreciated, Thanks for reading... CyRiX

Scraping noise sounds like you've got a water pump with issues.

As for the air bubbles, is it possible that you didn't get all the air out of the system when you bled it?

Im going to replace the water pump today and see what i get, and im pretty sure that when i bled the system. i got all or most of the air. if i squeeze the coolant tube comming from radiator to the engine when the car is off, i can hear a air escaping from somewhere.

Thanks

sorry it took so long to get back, replaced the water pump and flushed the anti freeze, filled it back up. and it seems to be doing alright, cant tell untill i drive but i have a flat now :/ anyone wanna trade thier luck with me?, gonna plug the tire tommarow and go for the first drive in 1/2 a month. thnx for the help

Took it for a test drive and it isnt fixed. still over heating. i had the coolant system pressure checked and it held pressure just fine. im really tired of this car, im rather dissapointed in this grand prix. my 89 prix ran 10x better than this one. do they get worse as they get newer?, anyway if anyone has any ideas why my system holds pressure and yet im getting air in the coolant please let me know.

thanks for reading.

it can sometimes take over an hour to bleed the cooling system on these cars. Since there was no problem before you changed the heater core and t-stat, I would bet you still have air in the system. Also check the "quick connect" heater hose fitting on the intake for a leaky o-ring

I bled it for like 1/2 an hour got alot of the air out after i replaced the water pump last night, ive checked all over and there are no leaks, everyone keeps telling me its a head gasket or a head. i cant see it being a head or head gasket when...

-the coolant system holds pressure
-there is no white smoke comming out of my exhaust, nor liquid.
-my oil is fine, there is no coolant in the oil or vise versa

i had the thermostat replaced after it started over heating, and for some reason when i run the engine up to about 2.5 to 3 thousand RPM's the temperature will fall. and when i turn the car off bubbles get into my coolant resevoir and there is alot of pressure in the coolant system, if i take the radiator cap off coolant will shoot out untill the pressure is relieved. i cant figure it out, i would just like to know before i spend
1300$ or more to have the heads and the head gaskets replaced.

Thanks

check the o-ring in the quick connect heater fitting. They will allow air in without letting coolant escape as they start to shrink.

Alright, went outside to mess with it again. this time i let it run untill it got to 210 degrees. i gave it some gas untill it went up to about 3k RPM's, let my foot off and the car idled down quickly and died. i did this again but i let it go to 2k RPM's, idled down fast and died. tried starting it up again and it was resisiting to start. got it to start and there was a bit of white smoke comming out of my exhaust, as well as a little bit of liquid, just very slowly dripping out of the tail pipes. and the smell of anti freeze. now im thinking its the heads or the head gaskets, i cant understand why the system can still hold pressure though.

Thanks for the help guys

Could very well be a head gasket. May not be enough pressure with the coolant system pressure tester to push coolant back into cylinders past the head gasket, but when it's running there is plenty of pressure due to compression and firing to push the exhaust gasses past the head gasket into the coolant. Also telltale sign of bad head gasket is if your antifreeze is turning brown and smells like exhaust. Hope this helps ya.

Wooz

you might check and make sure your catalitic converter isn't clogged or going out

just a check for ya. becuase on my first engine i overheated due to a
clogged cat

it could be a head gasket, or intake gasket. i have personally seen a head gasket leak air into a system before. there is probably a leak in the gasket between one of the cylinders.

short may be on to something, it could be a plugged catalytic converter. This would cause excessive backpressure in the system and cause your stalling problem. I've never known a plugged cat to allow air into the cooling system, but I've seen wierder things happen, and if your intake gasket is getting weak, it could be backfeeding exhaust pressure into the coolant ports through the intake.