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Discussion Starter · #1 ·
Okay guys, I have a over heating issue that is driving me crazy.
Let me begin by saying it's an 2002 3.4 impala with just below 100k on it.
Anyway... Ive noticed that I have been losing coolant and its getting more frequent. I dont seem to see any places that are leaking however. The water pump looks dry as does the surrounding area, no smell of coolant inside the cab from the heater core, the only hose that looked bad was the coolant bypass hose on top of the engine which I replaced about a week ago.
I drove it home last night and noticed low heat even at max setting... this morning no heat, then the temp gauge climbed up to the red and I pulled over to top off coolant and let it cool before turning home. by the time I got home it seemed to be doing fine.... Its gotten to the point that Im putting about a gallon of coolant in the thing every two to three weeks.
Ive bled the system repeatedly, bought the bleeding funnel set up that hooks to the radiator and have bled it from both bleeders. I cannot seem to get it to act right and I have NO clue where the hell its leaking from?
Im starting to wonder if the head gasket is going but the car seems to drive and run perfectly fine.
(the car is burning through oil as well, but the oil looks clean and is not contaminated with coolant, nor is the coolant contaminated with oil. its doing roughly a quart a month which makes no sense either to me bc its not smoking etc.)

Any ideas or things to look for would be appreciated because I have to get it fixed, its driving me crazy. im the 2nd owner and the first owner gave me a pile of reciepts for everything she had done to the car in its life... also, not sure if its the original head gasket or if they've been swapped bc I cant find any records on it.
 

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It helps to segregate the 2 problems: coolant disappearance & oil disappearance. I will address the coolant leak....
The coolant must be going somewhere....it doesn't just <PooF> into the ether. the obvious places for the coolant to go include external, oil, or combustion. The external leaks are more obvious....you should be able to see the coolant on the ground or in the engine compartment. Coolant leaking into the oil causes the oil to turn into a sort of chocolate milk shake...you will see it when you change oil. Coolant into the combustion chamber(s) is burned along with the gas and air. In that case you should be able to smell the coolant after the engine has been running. My 2002 S10 had coolant leaking into both the oil and into the combustion. You could smell it when the engine was running. Also the oil would come out of the engine with that foamy milk shake look to it. The problem was deteriorating intake manifold gaskets. Once those were properly replaced, there's been no coolant leak whatsoever.

A gallon of coolant every 2-3 weeks is rather a lot. I would expect that much coolant to present evidence as to where it's going. My 2002 S10 4.3L had plastic OEM gaskets from the factory. They worked fine when new but eventually deteriorate and need replacement. Your 2002 Impala might have the same issue. I don't know if GM used the plastic gaskets in all their 2002 vehicles or just the S10. Replacement gaskets (mine from Fel-Pro) are NOT made of plastic anymore.

So do a bit of detective work and let us know what you find......
 

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Discussion Starter · #3 ·
well thats the problem im having... I cant seem to find any coolant leaking externally. Everything looks dry (lower radiator hose looks a bit oily but I figure thats from the oil filter location when the oils been changed) The oil has been and is currently clean, Im thinking that its burning the coolant as I do sometimes smell coolant after the car has been running for a while. Ive checked the heater core and it also appears to be dry.
 

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Discussion Starter · #4 ·
also, and im not sure this matters but the car is running standard green coolant. Its not the dexcool orange. Not sure but Im assuming it had been switched over by a dealer during some work (because she had EVERYTHING done by a dealer before I purchased the car... even head lights.)
 

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Fasten your seatbelt, partner.
Just mentioning the symptoms, year and Model of your car, to most Service Writer's will have them suggest doing a Cooling System Pressure Test and and Engine Compression Test.
Y2K +/- 4 years was bad news for GM Engines and transmissions.
The engine problems, ... alone ... cost GM a fortune in settlements.
I'm sure Chevy took a beating when Overheating Issues related to early DexCool Antifreeze-coolant's detrimental effect on silicone and silicone based sealants dissolved the Lower Intake Manifold Gaskets on a whole bunch of people's last Chevrolet's.

Similar to others who've been down the path; you look for evidence of a leak.
An Intake Leak is tough to find.
Initially, the leak is internal. The amount small (at first)! The coolant either seeps into the combustion chambers and gets eliminated with exhaust; or drips into the Lube Oil where it gets boiled down and evacuated with the Crankcase gasses.

Here comes the rub.
Replacing the Lower Intake Gaskets is a labor intensive process.
IF, ... you find out that you need Lower Intake Manifold Gaskets, ... it may be wise to find a used Motor.

The labor swapping-out an engine (and transaxle), ... is hours less than tearing-down an engine to replace the Lowers, ... on an engine that overheated once or twice which might have suffered other complicating factors which could become costly.

I'd loan you my Infrared Laser-pointer Thermometer to go on a heat-seeking mission, ... but I dropped the damn thing!
An I.R. Laser thermometer is a great tool for sorting overheats.
Every time you point the laser at some place on your engine and pull the trigger; you'll get an instant temp reading.
They're great.
Until you drop it. Then, ... don't bother picking it up!
 
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