Coolant change in 2004 Impala

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I'm looking for a little advice. 2004 impala 3.4L ~99k miles and the coolant has never been changed. I also notice/hear some gurgling in the dash when making turns and accelerating from a stop, usually only when the car has been running for 10 minutes or less. I am assuming that this is air in the system from other posts I've read.

Anyway, I've read about Dexcool class-action settlements and so-fourth and I have a few questions:

What fluid do I need to use for the change?
Can I change it myself, or do you need someone with an exchange machine?
Anything else I should be concerned with?

Thanks in advance!
 
These engines are known for lower intake gasket failures. It's essentially inevitable that the gaskets will fail and leak coolant into the oil. That would be my first priority. Is the coolant level consistent, or does it drop often?

As far as changing the coolant, you certainly can drain the radiator. That will get about 4/10th of the total system capacity drained, so about 3 drain and refills will replenish most of the coolant. If you decide to get the gaskets replaced, the entire cooling system will be opened up so the coolant will be replaced.

I'd recommend using Peak Global Lifetime coolant. It doesn't have the gasket eating 2-EHA organic acid in it. It's also silicate and phosphate free. It's the most suitable replacement for Dexcool.
 
Thanks for the quick answer!

The coolant level has remained steady and have yet needed to fill it up.

So no-go on a Dexcool-to-Dexcool fluid replacement - even as GM recommends? I'll look into the peak lifetime formula.

Is it unheard of to take your own anti-freeze to a shop to use in their machine?
 
Originally Posted By: Drew99GT
These engines are known for lower intake gasket failures. It's essentially inevitable that the gaskets will fail and leak coolant into the oil. That would be my first priority. Is the coolant level consistent, or does it drop often?

As far as changing the coolant, you certainly can drain the radiator. That will get about 4/10th of the total system capacity drained, so about 3 drain and refills will replenish most of the coolant. If you decide to get the gaskets replaced, the entire cooling system will be opened up so the coolant will be replaced.

I'd recommend using Peak Global Lifetime coolant. It doesn't have the gasket eating 2-EHA organic acid in it. It's also silicate and phosphate free. It's the most suitable replacement for Dexcool.


I'd use something like Peak as well, but you can't mix coolants, or you get a gel like sludge in your cooling system greatly reducing its effectiveness.

If you are going to switch types, get it ALL OUT. If you just want to drain and fill gradually, just replace with the same that is in there.
 
GM redesigned the intake manifold gaskets for the 2004 model year, so your Impala should not be as susceptible to gasket failure as engines made in previous years.

That being said I would definitely drain and refill with fresh Dex-Cool at a bare minimum to prevent any sludge problem. My 2004 Chevy Venture has not had any intake or Dex-Cool problems, and I drain/refill the coolant every 3-years just to be safe.
 
Originally Posted By: BlastChamber
GM redesigned the intake manifold gaskets for the 2004 model year, so your Impala should not be as susceptible to gasket failure as engines made in previous years.

That being said I would definitely drain and refill with fresh Dex-Cool at a bare minimum to prevent any sludge problem. My 2004 Chevy Venture has not had any intake or Dex-Cool problems, and I drain/refill the coolant every 3-years just to be safe.


DITTO. Good to drain ANY coolant every 3 years or so... This happens to be something that so many owners forget to do.
 
Originally Posted By: BlastChamber
GM redesigned the intake manifold gaskets for the 2004 model year


And people are reporting that they still leak!
 
Originally Posted By: Drew99GT
Originally Posted By: BlastChamber
GM redesigned the intake manifold gaskets for the 2004 model year


And people are reporting that they still leak!


+1. The redesigned intake gaskets have metal inserts that prevent crushing the gaskets due to over-torquing. And they changed the seal bead material. But GM didn't address what is IMO the fundamental problem with this gasket design- their plastic frame. The plastic still deteriorates and cracks... and the gaskets still leak. It's not a matter of 'if', but 'when'- even with the new-style GM gaskets.

FelPro makes a re-designed gasket that holds up much better. It's a metal-framed gasket with rubber sealing beads- and it holds up much better than the GM gaskets.

Personally if I had a 2004 Impala with a 3400, I would replace those intake gaskets, flush the cooling system with distilled water, and refill with G05. IMO there's no reason to wait for the intake gaskets to fail- because they WILL fail. And when they do, they can dump coolant into the oil and destroy the rest of the engine.
 
You are probably correct about the 3400 but not everyone has had problems. As most GM cars with issues, it is hit and miss... Not every 3400 or 3800 has had leaks. BUT, here at this site we hear about all the bad gaskets. LOL.
 
Would it be okay to do the dexcool flush/fill myself using the prestone video guide or does the equipment at a lube place do it much better?
 
Last edited:
What prestone video guide? Is it the one where they tell you to drain the radiator, refill with superflush and water, drain radiator, refill with water then drain radiator, so 3 radiator drains? That will get most all of the antifreeze out. It's a little time consuming and I think the Impala's radiator drain is a little hard to access. You can also remove the lower radiator hose but that is probably not any easier. Another option is to install a T-flush in the heater inlet hose. This is probably easiest and most effective way.

As far as antifreeze choice, I agree with most of what onion said. Although I don't think using Dexcool or using another type is going to make much difference one way or the other with the gaskets. But one problem I see with the Impala is it has the cap on the radiator and Dexcool can sometimes gum with that setup, especially aftermarket Dexcool. I'd suggest Havoline Dexcool if you are going to go with Dexcool. It's a slightly different formula and seem to be more resistant to gumming. Other antifreeze suggestions, Peak Global Life from NAPA or Peak Professional from Pep Boys and G-05. And also change the radiator cap to a Stant 10230 or 11230 spring center cap that does a better job of keeping air out of the radiator. These are my standard suggestions with working with this year and make.
 
Thanks for the advice!

Questions:
Where can I find Havoline Dex-cool?
What is the best flush kit (t-adapter) for my application and will I not then need to use the radiator drain bolt?
Do I need to use a chemical flush additive (such as in the prestone vid)?
Any issues with flushing with non-distilled water (garden hose)?
What is the best way to get the air out of the system?
 
Thanks for the advice!

Questions:
Where can I find Havoline Dex-cool?

The only place I know of beside GM dealers is NAPA. they also carry Peak Global and G05. PEP boys carries Peak Professional.
What is the best flush kit (t-adapter) for my application and will I not then need to use the radiator drain bolt?

The Prestone T-flush kit would work fine. You will not need to use the radiator except to drain the excess water out before adding antifreeze. Although as the T-flush directions show you can displace the water by filling through the T-flush or the radietor with the t-flush cap off. I'd recommend draining the water out of the radiator though.

Do I need to use a chemical flush additive (such as in the prestone vid)?

That depends on how gunked up your cooling system is.

Any issues with flushing with non-distilled water (garden hose)?

Normally tap water is not a problem with dexcool as long as it's not really hard water.

What is the best way to get the air out of the system?

There is a bleeder that you open and fill the system until a steady stream of fluid comes out of the bleeder. You'll have to just run the car with the heater on until the thermostat opens.

I don't realize the answer were going to be colored in purple, was aiming for blue.
 
I did my 04 3800 a couple months ago and here is my advice.

You don't need a flushing machine to do it. Also don't need a T-flush kit that you have to cut your heater hoses to use. Here is what I did. Take the splash shield off the bottom of the car, it's like 4 bolts and will let you access the petcock easier. Open the petcock and drain the radiator. I went threw the process of multiply drain and fills using distilled water, something like 90 cents a gallon at walmart. Just fill the system up run till hot, heater on hot with fan off. Then drain and refill. After this I filled with new dexcool, straight dexcool and not the premixed stuff. I knew the total cooling capacity and since there was already some distilled water in the system I added half the capacity of dexcool. I think my system was 12 quarts total so I added 6 quarts straight dexcool, hope this makes sense. There is a bleeder valve on your engine, not sure where it is for the 3.4 but the 3.8 it was above the thermostat. I replaced the radiator cap, it's only a couple bucks and can make sure there is a good seal. I also had to add some coolant a couple times after driving for a while. Nothing major, just a little bit to the radiator, must have had a little air in or something. But after adding a splash 2-3 times it has been fine since and hasn't gone down at all.

Hopefully this helps a little. I was in your shoes a while ago and had lots of questions. Seems like everyone has there own opinion on what's the best way to do a coolant flush. It's easy to do and will only cost you the dexcool and some distilled water.
 
Thanks for the advice!

Scott37300, how many times did you end up filling and draining with distiled water before it drained clear? And when you initially drained the old coolant, were you able to get the fluid from inside the heater core as well?

I'm thinking about making a youtube video for this process to help others out like myself with this generation Impala. I just want to work out all the kinks and know what to expect before jumping all in :)
 
Ok here's my plan:

Not going with the T-flush, but...

I plan on draining and refilling the radiator with distilled water on 3-4 consecutive days, using my commute to work (~30 miles/day) as a way to let the distilled water mix/dilute/clean the inside of the radiator, block and heater core.

I'm hoping just having the distilled water in the cooling system for 3-4 days won't cause any problems before finally filling with the havoline dex-cool.

The nearly empty expansion tank looks pretty cruddy (at the bottom) and the inside of the radiator neck has some brown sediment clung to the sides. I'm wondering if the distilled water will be enough to clean the system out. 2004 impala w/ 107k miles and I think this is the first time the coolant will have been changed (I'm not the original owner).

I'm wondering a little chemical flush or cascade is in order (although I've read that the cascade is really more for oil)

Also, the radiator cap is actually a threaded style cap?! Is it even possible to convert it to a stant type/spring loaded or should I just stick with getting a new threaded cap replacement?

P.S. Any tips on cleaning out the expansion tank or will the distilled water pretty much take care of that too?
 
The distilled water will do some cleaning and will not cause any real corrosion problem over a day or two. The brown you are seeing is what dexcool does in this cap on radiator application. This is why I suggested Peak Global with the cap on radiator system but I think you will be OK with Havoline. The distilled water is probably not going to get it all off. But in this application the crud is usually constrained to the area around the cap and overflow bottle assuming the coolant hasn't been ran low very much and doesn't necessarily mean the rest of cooling system and engine is gummed.

You might consider using a bottle or two of super radiator flush or some other type of cleaner when you add the water.

The Stant 10230 spring-center cap (not spring-loaded)is a direct replacement and the spring center (instead of the original gravity drop-center) helps to keep air out of the system. Air is is the cause of the crud.

I wouldn't worry too much about trying to get the overflow reservoir perfectly clean. Usually you can take it off and flush it out with a garden hose.
 
Well so far so good. I did about 3 distilled water fill/drains since draining the old dex-cool antifreeze. I had a bit of a scare earlier after my first fill with distilled water. After running the engine for about 10 minutes, the thermostat suddenly spiked into the red zone and I had to shut off the car and let it cool. I'm pretty sure I had air in the system and probably not enough water. I had hastily filled the radiator with distilled water and forgot to open the air bleeds while doing so. I also didn't put any water in the expansion tank (was at the very bottom).

Now, I'm, making sure to open the 2 air bleed valves while pouring in distilled water and noticed that it took alot more to fill up the radiator.

The old dexcool which was drained, didn't look too bad. Came out slightly reddish-pink and didn't have any brown. I think I'll skip adding any kind of cleaner/flush chemicals and stick with the distilled water until it drains clear.

One question though, my cooling capacity is 11.3 quarts. The havoline dexcool only comes in 1 gal containers. Would it be unwise just to use 1 gal which would give me about a 35%/65% mixture anti-freeze to H2O, or should I just be safe and pay for the extra gallon of dexcool?
 
Also spent about an hour trying to clean out the sludge at the bottom and sides of the overflow tank to no avail. Tried Krud Kutter, Simple Green, water and coffee grinds, water and sand, boiling water and dishwasher detergent...nothing.
 
Originally Posted By: ljbrandt
One question though, my cooling capacity is 11.3 quarts. The havoline dexcool only comes in 1 gal containers. Would it be unwise just to use 1 gal which would give me about a 35%/65% mixture anti-freeze to H2O, or should I just be safe and pay for the extra gallon of dexcool?


I would get 2 gals and shoot for adding at least 5 quarts of concentrate added on the final fill. 35% antifreeze is a little low for best corrosion protection. You could always use the extra antifreeze for top ups later, maybe mix 1/2 gal of remainder antifreeze half with water in the used jug.
 
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