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Heat, coolant issues with 05 Impala

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Nov 16, 2014, 2:33 PM

Post #1 of 2 (2761 views)
Heat, coolant issues with 05 Impala Sign In

2005 Chevy Impala with a 3400 SFI, 110k miles.

I know you guys probably get this all the time, but I have no real knowledge pertaining to cars, so bear with me.

Started about a year ago, right with the dramatic change in seasons here in Wisconsin, where the car will have no cabin heat until the temp gauge slowly climes to the halfway point. When it gets close to overheating you can hear the sound of rushing water in the coolant reservoir, the temp gauge drops substantially and all of a sudden the cabin will have heat. This cycle will continue a couple of times and then it will level out for the rest of the day. Leave it cool overnight though and the process restarts.

The first time this happened I may have impregnated the system with air by forgetting to check coolant levels; I ran it almost dry. My dad and I changed the thermostat not knowing exactly what was causing it, and for the remainder of that winter things were fine.

Come spring and a change in weather it started all over again, but this time I waited until the engine was cool, checked and added coolant directly to the radiator (reservoir was full but radiator pretty low), let it sit and then proceeded to run it for thirty minutes driving and it seemed to go away after a couple of days.

First snow yesterday and we're at it again. I've taken it to proper mechanics but the problem didn't exist either time I took it in. I do hear a kinda rushing or gurgling noise through operating the car on a regular basis and wonder if the supposed air pocket I created the first time I let it get so low never really got out of there?

Slow increase in temp on gauge and no heat, sharp spike in temp once it goes past halfway marker, dramatic drop in temp combined with a noticeable sound of rushing water from reservoir and the appearance of cabin heat, repeat. What is this?

Head gasket was dropped in conversation with a couple of people, but I would almost think that things would just get progressively worse if it were the case, plus I asked the mechanics to look for those signs and they didn't see any. Could this just be a pocket of air that spikes with the change in outside temperature?

Reading tells me the SOP I should follow is probably a proper flush followed by a pressure check of the system to make sure air isn't getting sucked in anywhere else. Funny thing is I DO lose coolant, but from it being pushed out the back of the reservoir, no evidence in the oil. If anyone can lend some insight I'd be much appreciative; I want to have a plan of attack before I take it in to anyone to being work.


Ultimate Carjunky / Moderator
Discretesignals profile image

Nov 16, 2014, 4:30 PM

Post #2 of 2 (2742 views)
Re: Heat, coolant issues with 05 Impala Sign In

I think the idea of pressure testing the system to see if you can locate leaks is a good first step. If the coolant is overflowing the reservoir, make sure your radiator cap is functioning properly. Just because you don't see coolant in the oil doesn't mean you don't have a head gasket issue, but usually a head gasket problem that is allowing combustion gasses to enter the coolant system will also cause the engine to overheat.

Also make sure that you have the proper concentration of antifreeze to water.

Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Nov 16, 2014, 4:34 PM)

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