LShoning

I have a 2005 Chevy Impala 3.4L that keeps over heating. It started last summer, when we changed the water pump and the themostat. everything was good after that until more recently, the overheating is back. I have had the radiator, intake gasket fixed. I also replaced the thermostat again. everytime it has been in to get fixed, my car will come back and be great for a few days until the overheating starts up again. I'm completely lost on what to do next!! Before the overheating starts I watch my temperature gauge start to spike up, and it will go down, it continues to do that until I have to pull over for a few minutes to let it cool down. PLEASE HELP ME! I can't afford to keep up with this car anymore.

Impala-Blue-2.

Have you checked to see if the electric cooling fans are turning on when they are supposed to ? Has the system been properly flushed out to make sure there is no debris in it ? Is it actually overheating or a bad temp sensor giving bad readings ?

LShoning

The fans are working properly, and I had 2 different people bleed the system as well. I also had a flush done during my last oil change.

sledge.impy

Does your car still overheat if you turn your inside cabin heater on HIGH?

sledge.impy

And is it overheating when driving or when idling at a red light or parked for an extended period of time?

Is it really fast ? or takes 15-20 minutes as you slowly watch the gauge creep higher?

Are you running your AC when it happens?

LShoning

Heater and the air stay off. It takes about 15 minutes for it to actually overheat. It does mostly occur when at a red light, however has happened just while driving.

Yes it does still overheat when heater is on high.

sledge.impy

This is hard to diagnose from afar.

If your fans are bad - it would overheat only when stopped, and turning the heat on high should help prevent this.

There still might be air in the cooling system causing a blockage and lack of coolant flow. Bleed again?

Unless - your water pump is bad again and not circulating the coolant - which would be rare.

We can only assume you put the correct rated degree thermostat in the right way, and not backwards?? Sometimes you can forget orientation when removing it or if it falls out and you never see which way it was. Or the guy before you put it in backwards and you just followed his lead.

LShoning

I will try to bleed it again and see where that gets me.
The water pump is less than a year old, I really don't think it's that. I hear my fans going when I open the hood, and turning the heat on high does not help, I've tried. I had a mechanic put in the thermostat, so I trust that it was put in correctly.

sledge.impy

Do you feel heat being blown off the fans or is it cold? I guess the gauge/sensor could be bad... but those usually wouldn't show a general overheat condition where it is climbing.

Kind of hard to tell I guess... just don't get your hands whacked by the fan or get a neck tie sucked up in the fans or you will die.

Can you post the steps you take for when you bleed the system... just so we know you are doing it properly.

LShoning

I don't think it's a bad sensor, my car will begin to shut itself down if I take too long to pull over. Also, I didn't bleed it myself, I have a family member that did it once also our mechanic did it another time. We will try again tonight, can you post the correct way of doing it so we don't miss anything.