overheating problem

[uspres2020]

I have a 99 Grand Am 3.4L engine with 98,000 miles on it.

A couple days ago it started overheating. I am able to drive the car for about 10 or 15 minutes at normal operating temperature and then the temperature slowly starts to creep up. Only one time was it able to get so hot without me noticing that the temp light came on.

It is not leaking any coolant except through the overflow after it overheats. I replaced the thermostat. I am going to try the air bleeding procedure that xeroinfinity has posted.

Any other suggestions would be great, it seems so odd to me that I am able to operate at normal temp for a while before the overheating starts, and it is consistently like this.

[thephantom1492]

sound like a failing water pump

[youngkia1]

I'm agree, when a my car overheating i will check first the water pump, most of the time this is the problem. Try to check it out. If no changes at all ask advice from the expert or mechanic.

[uspres2020]

I did not get much air out and it did not make any difference. I have no reason to believe that the cooling capacity of the radiator could have diminished due to damage or clog so I also think that a failing water pump could be the problem.

I don't know a lot about these pumps, is it just that the impellers get worn or something. That is what I am suspecting as it seems the cooling capacity has just dropped marginally in this case. I am excited that a new one is like $20. I will most likely pick one up today and install today as it looks very easy to get too, probably easier than the thermostat was.

[skeeter123]

before you replace the water pump, check out:

http://www.automotiveforums.com/vbul....php?t=1012323

See if your system comes up to pressure after 10-20 minutes. No pressure = problem. Check reservoir cap (~$5 to replace); get coolant system pressure tester (some auto parts stores loan them out) and do the pressure leak-down test.

[thephantom1492]

the pump itself isn't hard to replace, provided that you can get to it
However... beware that usually the pump is driven by... the timing belt/chain!

Since you would be messing with it, you might want to also change the belt/chain, specially if it's a belt!

[3100]

replace t-stat, pump & cap.

[uspres2020]

I did a flush with one of those bottles for flushing the coolant system. That made no difference. For now I am just running it with the fans on all the times and it does fine. I just have to turn the A/C on when I first get in the car to turn the fans on and then they stay on and they keep the temp down. I bought the water pump but didn't put it in yet. I think I will put the pump in this weekend just to see if that will make the difference.

Do these pumps get worn down some how or lose pumping capacity slightly at some point?

[thephantom1492]

So you mean the fans do not turn on when the coolant is hot?

The sequence should be: cold -> heat up -> thermostat open -> heat up -> fans turn on -> cool down -> fan off -> heat up -> fan on ... and so on

if the fan do not turn on, then possibly that the "electronic" thermostat has failed.

I first assumed that the fan was running as expected

[uspres2020]

The fans on this car turn on when the car gets to 223 degrees or when the pressure in the A/C lines is above a certain point which basically turns the fans on once you turn the A/C on.

[skeeter123]

So, have you checked to see if it holds pressure?
My take is that water pumps usually fail by leaking, not by losing the ability to pump. Does your heater work? If you run it for 5-10 mins and turn on heater, do you get hot air? If so, your pump is OK.
Nothing should be coming out of the overflow until the pressure is >15psi; unless the reservoir or cap is bad.

Replacing the water pump at 98K miles is a good idea, I'm just concerned that it might not be the cause of your immediate problem.

[uspres2020]

I'll check out the cap. It doesn't screw on very well, feels like it is all cross threaded and you have to turn it a million times to put it on all the way. Maybe I should just buy a new cap.


I think I will do that before I put the water pump in just to see.

[uspres2020]

Cap did not work, car is still overheating. Time to put the water pump in now.

[uspres2020]

Replaced the water pump, that did not fix it.

A close friend who is also a mechanic had been telling me since the beginning that this is a sign of a blown head gasket so we changed that today as well as all other gaskets. Still overheating.

Very unhappy about this.

So far I have replaced thermostat, water pump, expansion tank cap, and all gaskets. I have no ideas. I think I need a new car.

[thephantom1492]

A blown gasket would cause coolant leak and/or exaust in the coolant, causing bubbles. the leak would cause the coolant to leak out, to be burned or to mix with the oil.

I'm starting to wonder if the problem could be... electric...
Like a faulty temperature sensor...