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Impala overheating

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Nov 20, 2012, 2:38 PM

Post #1 of 5 (3879 views)
Impala overheating Sign In

Hey guys. New to the forum here and have an issue. I have a 2004 impala 3.8 with some serious overheating issues.

This past June, it overheated on me due to the plastic heater core elbow rupturing. During the repair of this part, I replaced the thermostat, the water pump, and the elbow. Everything has been working fine up until this week when the car would start to overheat while idling. Also the heater would start blowing cool air until the thermostat would open up and the gauge would go back down (I assume). After a couple days of this it began to get hot while driving as well.

Just this morning I replaced the thermostat which seemed to help for a little while, however after driving for about half an hour the gauge began to creep up again. While looking at the engine while hot I touched the elbow and it split open big time, spraying me in the face with some extremely hot antifreeze. I guess what I'm asking is this, does this sound like it had a small leak at the heater core elbow due to degradation or does it sound like maybe the water pump I bought crapped out on me? Doing the work doesn't scare me I'd just like some opinions or first hand experiences so I don't waste any more time or money than necessary. Thanks in advance.

MarineGrunt profile image

Nov 20, 2012, 4:15 PM

Post #2 of 5 (3852 views)
Re: Impala overheating Sign In

We have a 2002 Chevy Venture with the 3.4L. About 8 months ago it acted almost exactly how you're describing. The heater would blow cold air until the thermostat opened up. It would then blow hot air and the temperature gauge would go back down. At first I figured it was the thermostat so replaced it. It didn't fix anything. After a few days it got hot while driving also.

The 3.1, 3.4 and 3.8 are notoriously known for bad lower intake gaskets. There is an improved design that replaces GM's originally faulty design. The mechanics here told me to look on the back driver's side of the engine with a mirror. I had to take the air duct off to see, but once I did, I could see some slight bubbling from the intake.

Don't go tearing into it until the mechanics on here give you some better advice but I'd put my money on the intake though.

I know I had the 3.4 but I might have some pictures from when I did mine. I'm sure they are somewhat similar. If you need me to post any pics just let me know.

Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 20, 2012, 4:20 PM

Post #3 of 5 (3843 views)
Re: Impala overheating Sign In

You're first step is pressure testing the cooling system to find the leak. The intake problem that MG referred to is quite common mainly in the 3.1, 3.4, 4.3 and the small block V8s. The 3.8s aren't as common.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.


Nov 21, 2012, 11:24 AM

Post #4 of 5 (3811 views)
Re: Impala overheating Sign In

Thanks for the reply guys. Not sure about the pressure yet, but I did replace the heater core intake tubing this morning. It actually didn't help at all even though it was broke inside the belt tensioner housing. I did notice that my radiator didn't want to take coolant so that may be where I nee to look next.

Veteran / Moderator
Sidom profile image

Nov 21, 2012, 9:30 PM

Post #5 of 5 (3791 views)
Re: Impala overheating Sign In

I addition to leak checking the system you want to verify that the cooling fans are coming on..

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