[allenj280]

Hello everyone! My girlfriend has a 2004 Impala. It has about 75,000 miles on it. A couple days ago she noticed that when she had the heat running it would go from warm to cold, never getting hot like it used to (keep in mind it is September). She also notices that when she is stopped and idling, the temp jumps up more that she has seen before. I checked the coolant level and it is fine, no idiot low coolant lights either. I do not see any sort of leak near the water pump or around any hoses. She is taking it to the dealership on Monday and I was wondering if anyone here could give me some guidance as far as what else it could be. Please correct me if I'm wrong here, but, I told her that it could be one or more of the following:

1) cooling system needs to be flushed, could have air in system (She had this done at...LOL...Sears at about 50,000 miles)

2) bad thermostat

3) leaking coolant (cannot locate any leak myself)

4) bad heater core (I think they usually leak if they go bad)

5) bad water pump (cannot see any leaks while engine is running)

Any advice would be greatly appreciated.

Thanks,
James

 

[77Impala]

How low is the gage reading while the car is in motion? If the temp gage drops way down towards or stays on or near the cold mark then I would change the thermostat. Have the flow in the radiator checked if slow but not clogged then your water pump vanes may be worn out. With the engine running and at operating temp see how warm the heater hoses are, if cool then see if you can flush a lot of water through it, if so then again check the water pump.

 

[04DetroitLS]

lower intake manifold & gasket, ecpecially if it's a 3.4, if it's a 3.8 find a 05+ 3.8 LIM/UIM from a junkyard (www.car-parts.com) L26 engine code, try searching 06 buick lucerne, the newer 3.8 uim/lims are alum, not plastic, order the "green" gaskets from intense/zzp

 

[capricewiz]

dorman makes a nice upper plenum kit, with a limited lifetime warranty. I put one on a customer car a couple of weeks ago, I was impressed.

 

[allenj280]

Update: Well, I think I may have figured out the problem. I think it is a bad thermostat. GM did a real nice job of putting the thermostat in a spot that is almost impossible to get to without taking a bunch of stuff off first. What I have done is this. The car had been sitting overnight. I grabbed the hose between the radiator and the thermostat. I squeezed it and I could hear the reservoir gurgle. That tells me that the thermostat was stuck open. I drove it for a bit, maybe a few blocks and the temp rose very slowly, but, when it did it went almost to 250 deg. I parked it, popped the hood and squeezed that hose again and no gurgle. Now, maybe I am wrong, but, that should mean that the thermostat was stuck closed. The hose was also hot, but, cool enough that I could grab it. I let the car sit for a few hours and checked it again. I could then squeeze the hose and hear the gurgle. Now it was back to being open again. Any thoughts would be greatly appreciated.

 

[allenj280]

Update again: Dealership has figured it out.

1) The thermostat is bad and is causing all the overheating and lack of heat

2) The water pump is leaking. I saw this myself but was unsure if it was coming from the water pump, it wasnt very much.

3) The serpintine belt is bad.

Thanks for all the help.