What could be wrong with my 2000 Grand Am cooling system? (all possibilites)?

Question

Here's the story:

My car was overheating and come to find out it was due to a bad water pump. Got the water pump changed. That day I drove quite a ways when later in the evening while I was idling my coolant started coming out of the overflow and also thru the cap. The engine temp was reading about 220. I initially thought it was due to a bad head gasket from the overheating, but an employee at Auto Zone declined. He said I would have smoke from tailpipe and anti-freeze mixed in with oil (oil would look like coffee). This weekend I noticed that the only time the temperature goes above 200 is when I am idling. If it starts to rise and I start driving and turn the heat on full blast the temp drops back down to 200. As soon as I idle again it starts back to rise and I repeat the process and it goes back down to 200. What are all the possible things that could be wrong? If I need to bleed the system is it something simple, and if so how?

Could it be that I need a new thermostat? The mechanic that changed the water pump said that he heard the thermostat clicking which means it is working. Also, should anti-freeze be coming thru the pressure cap at 220 degrees? (I don't think that should be happening) I'm looking for any and all possible problems that could be causing the rise of temperature when I am idling.

i looked directly in the oil tank and the oil was dark dark. the attendant at auto zone told me if there were anti freeze in there it would look like creamy coffee.

By the way, I can drive on the freeway with the a/c on with absolutely no problem, it's only when I begin to idle does the temperature begin to rise. At 220 is when the antifreeze begins to blow thru the pressure cap and overflow.

Both of the fans work.

how do you purge air from the cooling system?

Answer 1

i too think its your thermostat. also, what about your fans? are they on when you idol?

when was the last time you had your coolant flushed?

Answer 2

The mechanic heard the THERMOSTAT clicking???
Thermostats don't click. I think he must have meant your fan sensor solenoid clicked when it got too hot and started the fan/fans...
You put a thermostat in a pot of water with one of those food temperature testers, set it on the stove and let the water warm up until the thermostat opens up.
Look at the tester then you know if the thermostat works or not at the right temperature. The temp the thermostat opens up is stamped on the thermostat.

You need to get your cooling system pressure tested somewhere to see if you may have a possible leak in the system. I wouldn't believe an Autozone guy telling me I didn't warp an aluminum head at 220 degrees. It doesn't take much to slightly warp them, creating a gap in a gasket once the engine gets hot.

Answer 3

just because thiers no water in the oil or no steam out the exhaust doesnt mean you dont have a cracked or warped head most of the time on these engines the exhaust will go into yhe cooling system with the engine cold take the radiator cap off then start the car and look to see if exhaust is coming out of the radiator you may be able to smell it also but be carefull putting your face close to the radiator.

Answer 4

check your antifreeze mixture it should be 50/50 . It should not be boiling out the cap at 220. Only reason it would boil out is if the cap is bad and the antifreeze mixture is to lean. overheating conditions 1 . debri in front ot the radiator 2 debri between the condensor and radiator 3 . bad thermostat 4. have radaitor boiled and inspected

Answer 5

normally, if you have water boiling back out the cap, your thermostat is bad. Also, did you purge any air bubbles from the system when you refilled with coolant? My sons Chevy Beretta had a bad problem with that, we really had to work at it to get the air out. Keep checking around the top of the oil dipstick too, look for a whitish color mixed in with the oil, that would indicate that the head gasket really is blown.

Answer 6

You never mentioned if your electric cooling fan can on, this would account for only overheating when ideling, and with the a/c on the cooling fans kick on to keep the condenser cool, I would change the fan switch or the coolant temp sensor, your car has one of these and it is your problem, for sure

Answer 7

You may want to have your radiator cap checked. Sounds like it may not be holding enough pressure on the system. If it is not holding full pressure, or not always holding full pressure, it will allow the coolant to boil. If in doubt, just replace it. They are fairly inexpensive.