Your thoughts on changing antifreeze on 4th gens

[SS_CarGuy]

I just had the antifreeze changed on the SS. I debated on doing it myself but I really have no good way of recycling the old anti-freeze. Besides that I couldn't find the drain plugs on the LS1 block that they tell you to open to drain the block (the shop manual tells you to do this but doesn't even give you an illustration showing you where they are located). I looked high and low for these things and if they are there I am either blind (a definite possibility) or they are just hidden from view. The radiator drain outlet was no problem to locate.

Anyways back to the subject. I watched the technician do the job at my local Chevrolet dealer and I question whether these machines they use really get all the old antifreeze out. If you have never seen one in operation, here is how they do it. They remove the radiator hose from the drivers side of the radiator located half way down the tank.....which automatically drains half the radiator into a tub they place under the car. Then they attach fittings and hoses from their machine to the radiator opening that the hose had been attached to and to the car's radiator hose that's been removed. Then they mix 2 gallons of antifreeze and two gallons of water and placed it into the inlet tank on their machine. (BTW........the cooling sytem capacity is 15.3 quarts or almost equivalent to the 4 gallons they have mixed.) There is also a recovery tank on the machine to collect the old antifreeze. Then they start the car letting the cars water pump do all the work of supposedly sucking in the fresh coolant while the old stuff is alledgedly going out to the recovery tank. As the engine runs the "theory" is that the water pump will pump all the old fluid out replacing it with the new. My theory says that no matter how hard you try you are still mixing the new with some of the old and therefore it doesn't get it all replaced with fresh stuff. I know every shop uses the same basic machine and method to change antifreeze these days but I just don't think it does a good job.

Anyone else have any thoughts on what kind of a job they think these machines do?

BTW......my old DexCool still looked good. I had heard so many horror stories about this stuff, I didn't know what to expect. It has been in the car for over four years now.

[TraceZ]

I know it sounds terrible, but I've always let my old coolant run down the driveway in the storm sewer. I know... I'm a terrible person.

[MN6WS6]

On the LT1 cars, how do you do this? I thought I read something about "reverse cooling" or something, and I figure I'll replace the coolant when I do the electric water pump conversion, Optispark, and new AC compressor.

Heck, while I'm doing that I'll put in a cam, new heads, new rotating assembly, rebuild the tranny, AACKK!!

But seriously, I would like to know the proper 'shadetree' way of doing this.

[Roger in Kensington]

I got rid of . . .

. . . the Dex-Cool years ago and have been using regular antifreeze ever since, changing it every two years (car has less than 27,000 miles on it now).

Don't know about the flush technique that you describe. My concern is that the shop (because I would no longer do this myself), get all the air out of the system to avoid hot spots.

[Al 96 Ram Air T/A]

Off subject, but...

The best way to dispose of old antifreeze is to pour it into your toilet. The sewage treatment plants are designed to handle this waste. Now, letting run into the storm sewer is NOT a good idea. It's actually illegal in most states.

As for Dexcool...my personal feelings are that most of the "horror" stories are a result of the "leak stop" and not the coolant. The leak stop pellets look (for lack of a better description) like black snot! I was blown away by what I found in my recovery tank. Gobs of black boogers. My neighbor is a Pontiac mechanic. He explained exactly what I was looking at. At first, I thought the oily residue I was seeing on my dipstick (coolant) was a result of a blown head gasket. As it turned out, it was simply the leak stop pellets they used. As to why GM still uses these, as he stated, it's GM's fix for everything. Should the system develop a leak, the leak stop will clog it up. At least long enough until the 3 year/ 36,000 mile warranty expires

I continue to use the Dexcool. As long as you change it out every 5 years/50,000 miles, I can't see why it would cause a problem. Heck, it's merely the green stuff with orange coloring added minus the silicates to make it aluminum friendly. True coolant is nearly colorless. Manufacturers have added color to differentiate their products over the years. Toyota "red" is standard antifreeze. GM "orange" is long life. Prestone makes a long life "green" and a standard "green"...just to confuse us more...It's all smoke and mirrors.

[SteveH95Formula]

Originally my car had the old 'Green stuff' but I had my dealer put in the new Dexcool antifreeze a few years back. I've flushed it late last year and it didn't look too bad.
Probably the best thing to do is drain as much as you can and fill with striaght water and drain that again. and fill with new Dexcool.
There is an insteresting article on coolant in Corvette Magzine about the various coolants and they say even the new dexcool should be changed every four years or so to replenish the corision inhibitors that protect brass (freeze plugs) and aluminum (heads, intake, water pump, and block on LS1).
After a while the protective coating that covers aluminum degrade. Quoting from the article "When fresh, the inhibitors in antifreeze and water-wetters (They where comparing water-wetter products) provide protective films that are good enough to stabilize most metals, (Cast iron, aluminum, brass etc.) and their inherent alkalinity helps prevent electrolysis. Both of these characteristics dissapear over time, however, leaving aluminum parts particularly vulnerable to electrolysis."
In effect the inside of the engine is a big wet cell battery eating away at itself.
The article is pretty intersting its the January '05 edition of Corvette magazine.

[Injuneer]

On the LT1 cars, how do you do this? I thought I read something about "reverse cooling" or something, and I figure I'll replace the coolant when I do the electric water pump conversion, Optispark, and new AC compressor.

Heck, while I'm doing that I'll put in a cam, new heads, new rotating assembly, rebuild the tranny, AACKK!!

But seriously, I would like to know the proper 'shadetree' way of doing this.

Best bet on your LT1 is to pull the block drain plugs. On the passenger side of the block, that is the knock sensor. On the drivers side, there's a pipe plug screwed into the drain hole. Both these are difficult to reach, because the motor mounts block access. But pulling the plugs it the best way to insure minimum contamination of the new coolant with the old.

Simply draining the radiator, filling the system with clean water, and running the car 'til the t'stat opens up is not very effective. Draining the radiator only removes 50% of the old mix, the other 50% is still in the engine. Fill the system with water, heat it up, then drain it, and you still have 25% of the old mix in the system. Do it again, and you're down to 12.5%.... and so on.

The LT1 is not an easy system to deal with as far as coolant is concerned. You also have to flush the heater core independantly when you do a coolant change, or there is no guarantee the coolant is even flowing through the heater. Bleeding the system of air is the final difficult, but necessary step.

[bigtow]

hmmmm

i am not trying to hijack the thread but i changed the coolent in my car not to long ago and every now and then after a short run when i switch the car off i get rumbling sort of noise from under the dash area do you think that ther could be air stil in the system i thought i had blead the system fully. also i have got a 160 tstat fitted and now the winter is here and i do most of my driving at night on the motorway(freeway) the temp gauge never goes over the second 0 of 100 can this cause a problem. sorry if i have hijacked the thread but it was going along the same line of thought