Safe effective cooling system flush?

[55Test]

My brother's 2004 Grand Prix GT has some Dexcool sludge in the coolant recovery bottle and in the radiator filler neck, so he wants to flush it and put new coolant in. What's a good, safe and effective flush to use? My first thought was to use Prestone super radiator cleaner (the stuff you leave in and drive a few hours) but I read a few comments on other websites that seem to say it might not be all that effective. Is the Prestone stuff good or should he look for something more powerful? Also, how exactly do you use it? Most of the flushes say to drain the radiator, pour the flush in and refill with water. I always thought you would want the cooling system completely free of any coolant before you run the flush. Which way is right?

And one more question. Which coolant should he use to refill with? Should he go with proper Dexcool or one of those universal long-life coolants?

 

[JHZR2]

I've heard rmi-25 (or something along those lines) is good. I've used citric acid flushes in my 30yo Mercedes Benz cars and have entirely original cooling systems.

I've also in the past used the zerex flush products just to clean one area.

 

[MarkStock]

Most flushes are ok since they won't be in there for long.

How do you use it? Follow their instructions!

But what you want to do at the end is rinse it out several times with distilled water before adding coolant.

Once you are satisfied that your system has only got distilled water in it, you want to drain the distilled water, add exactly half the system's capacity of 100% coolant, and then top up with distilled water.

Each drain will not get 100% of the old coolant / flush / flush and distilled water / distilled water out. That's why you need to rinse a few times with distilled water after using a flush and then use the method I mentioned to add coolant. That's the only method that ensures you have only new coolant and distilled water in there.

Which coolant to use is always the manufacturer's recommended because it is formulated for the chemistry of the system.

 

[The Critic]

Maybe try some BG cooling system flush. You can get it on eBay.

 

[crazyoildude]

be careful... Sometimes if you lean them you get leaks get the dex cool ouT

 

[HTSS_TR]

Install Prestone T-flush to the heater hose, flush with garden hose for several minutes with radiator cap and petcock open, and heater at max temp. Close the radiator petcock then add citric acid into radiator and top off with tap water. Drive for several days then flush it out completely. Use several gallons distill water to flush out tap water, close the petcock then add concentrate antifreeze to half capacity and top off with distill water.

I had Prestone T-flush in my LS400 for more than 14 years without any problem. Many people afraid of it because of potential leak around the T-flush.

 

[Drew99GT]

Originally Posted By: MarkStock
Most flushes are ok since they won't be in there for long.

How do you use it? Follow their instructions!

But what you want to do at the end is rinse it out several times with distilled water before adding coolant.

Once you are satisfied that your system has only got distilled water in it, you want to drain the distilled water, add exactly half the system's capacity of 100% coolant, and then top up with distilled water.

Each drain will not get 100% of the old coolant / flush / flush and distilled water / distilled water out. That's why you need to rinse a few times with distilled water after using a flush and then use the method I mentioned to add coolant. That's the only method that ensures you have only new coolant and distilled water in there.

Which coolant to use is always the manufacturer's recommended because it is formulated for the chemistry of the system.


Could not have said it any better!

I'd add that it's easier to get maximum flow through the system by removing the thermostat and reinstalling the thermostat housing, which is super easy to do on a GM 3800.

In fact, I'd say, if there isn't any built up scale in the radiator but just slime in the overflow tank, you can flush the system with the thermostat out with no need to add cleaner. Just rinse out the overflow tank and radiator neck.

Once you get it clean, make sure the cooling system level doesn't go low. Air seems to be the culprit with Dexcool turning to slime, and if it's losing enough coolent, the intake manifold gaskets might need replacing.

 

[yonyon]

You might also want to consider buying a new coolant recovery bottle. If you get a new one it's one less thing to clean. It's been a while since I bought one, but the last time I bought a coolant recovery bottle from the local Pontiac dealer it cost less than buying two chilli dogs at the local hot dog joint. I think it was around $12 and change for the bottle and $8.50 for a chilli dog.

 

[chad8]

http://www.paulstravelpictures.com/GM-Pontiac-Grand-Prix-Engine-Coolant-Antifreeze-Change-Guide/

I would not use a chemical flush . water is enough.

This automotive "how-to" guide was specifically written to assist owners of the 1997 to 2003 Pontiac Grand Prix in draining the engine coolant (antifreeze) from the radiator and re-filling it with fresh fluid.

Owners of other General Motors vehicles equipped with the 3800 Series II L67 or L36 engines such as the Pontiac Bonneville, Firebird, Buick Regal, Park Avenue, Riviera, Le Sabre, Chevrolet Camaro, Impala, Lumina, Monte Carlo, Oldsmobile Eighty-Eight, Regency, Intrigue, LSS and Holden Commodore may also find this guide to be useful.

The tools needed to complete this coolant change procedure include a floor jack, jack stands, a 10mm socket, a funnel and a pair of pliers.

Other items needed are a gallon bottle of Dex-Cool approved antifreeze/coolant and a gallon of distilled water. Optional parts include a new radiator cap, a new thermostat, and new radiator hoses if these things have never been replaced.
GM-Pontiac-Grand-Prix-Engine-Radiator-Coolant-Antifreeze-Change-Guide-004
Push Down & Rotate Cap GM-Pontiac-Grand-Prix-Engine-Radiator-Coolant-Antifreeze-Change-Guide-005
Jack Up Passenger Side GM-Pontiac-Grand-Prix-Engine-Radiator-Coolant-Antifreeze-Change-Guide-006
Lower Engine Cover
The first step is to allow the engine to cool almost completely. (Do not remove the radiator cap when the motor is hot to avoid being sprayed by hot coolant and injuring yourself.) When the engine is cool, remove the radiator cap. Rotate the cap about 1/2 turn counter clockwise. Then push down firmly with the palm of your hand and turn the cap another 1/2 turn counter clockwise to fully release it.

Next raise the hood, lift up the passenger side of the car with a floor jack and securely support it with one or more jack stands.

Gather together a 10mm socket with ratcheting wrench, a pair of pliers (hose clamp pliers are best), and an old coolant catch container such as a bucket. You may also need a small flathead screwdriver to release a wire loom fastener for extra working room below the vehicle.
GM-Pontiac-Grand-Prix-Engine-Radiator-Coolant-Antifreeze-Change-Guide-007
Lower Radiator Hose GM-Pontiac-Grand-Prix-Engine-Radiator-Coolant-Antifreeze-Change-Guide-008
Remove Three 10mm Screws GM-Pontiac-Grand-Prix-Engine-Radiator-Coolant-Antifreeze-Change-Guide-009
Draining out the old coolant from the radiator is best done by removing the lower radiator hose located on the passenger side near the front of the car and just above the black plastic engine bay cover.

The radiator is equipped with a plastic drain bolt, but it is prone to leaking especially if it hasn't been removed in years. A coolant leak is far less likely to occur after removing and replacing the lower radiator hose that is held in place by a very strong metal spring hose clamp.

If any of your radiator hoses look dry, brittle, cracked or deformed, stop now and go buy new hoses to avoid wasting all of your fresh coolant when an old hose bursts or splits.

Some of you may be able to just pull down the lower black plastic engine cover and access the lower radiator hose. I found it easier to access the hose and clamp after removing the three 10mm screws that hold it to the underside of the car.
GM-Pontiac-Grand-Prix-Engine-Radiator-Coolant-Antifreeze-Change-Guide-010
3 Engine Cover Screws GM-Pontiac-Grand-Prix-Engine-Radiator-Coolant-Antifreeze-Change-Guide-011
Release Cable Loom GM-Pontiac-Grand-Prix-Engine-Radiator-Coolant-Antifreeze-Change-Guide-012
Radiator Hose Clamp
If you still don't have enough working room, use a small flathead screwdriver to release the snap fastener holding the large wire loom in place along the sub frame.
GM-Pontiac-Grand-Prix-Engine-Radiator-Coolant-Antifreeze-Change-Guide-013
Bucket Catch Container GM-Pontiac-Grand-Prix-Engine-Radiator-Coolant-Antifreeze-Change-Guide-014 GM-Pontiac-Grand-Prix-Engine-Radiator-Coolant-Antifreeze-Change-Guide-015
Compress Clamp With Pliers
Next grab the pliers and your old coolant catch container. Carefully compress the metal hose clamp on the lower radiator hose with the pliers and slowly wiggle the clamp backwards. Be sure to have your catch container directly below the hose and spread around some newspapers or rags to soak up any old coolant that may spill on to the ground.
GM-Pontiac-Grand-Prix-Engine-Radiator-Coolant-Antifreeze-Change-Guide-016
Slide Back Clamp GM-Pontiac-Grand-Prix-Engine-Radiator-Coolant-Antifreeze-Change-Guide-017
Pull Off Lower Radiator Hose GM-Pontiac-Grand-Prix-Engine-Radiator-Coolant-Antifreeze-Change-Guide-018
Distilled Water For Flushing
Once the hose clamp has been slid back at least 2-3 inches away from the radiator, you can carefully pull the end of the hose off the black plastic spout on the bottom passenger area of the radiator. Point the end of the hose into the bucket.
GM-Pontiac-Grand-Prix-Engine-Radiator-Coolant-Antifreeze-Change-Guide-019
Old Coolant & Flush Water GM-Pontiac-Grand-Prix-Engine-Radiator-Coolant-Antifreeze-Change-Guide-020
Lower Car From Floor Jack GM-Pontiac-Grand-Prix-Engine-Radiator-Coolant-Antifreeze-Change-Guide-021
Replace Radiator Hose
When the old coolant draining out slows to a trickle, remove the catch container and add extra newspaper or rags below the car. Lower the car from the floor jack and jack stands to allow a little more old coolant to flow out from the engine and radiator.

If you are going to "flush" out the radiator, read below. If not, just continue to the pictures below these next few paragraphs. (If your old coolant looks as clean and brightly colored as mine does in the bucket above, you can skip flushing.)

Some people recommend flushing out the radiator with a garden hose to flush out any contaminants. The water in my area is very "hard" and filled with minerals that may be harmful to the cooling system. So I chose to instead flush out the radiator with some distilled water from an old bottle of Peak Battery & Radiator Water that I wanted to throw away.

Flushing out the radiator is not even absolutely necessary as long as you plan on draining and filling the radiator with fresh fluid every few years. Draining the radiator removes about 4-6 quarts of old coolant and the entire cooling system holds almost 12 quarts of fluid. Since the Dex-Cool antifreeze has an approximate life span of 5 years or 150,000 miles, renewing the system with 1/3 to 1/2 of the capacity with fresh coolant every few years is more than enough preventative maintenance.

 

[eljefino]

Citric acid flushes are intended to get lime scale out, from areas with "hard water". This does not sound like your problem. I would do the above ^ but drain, fill with water (if above freezing, nights), drive around for a day, dump, repeat. Then refill with 100% antifreeze to get it all right.

For the overflow tank, those come off easy. Put a tablespoon of automatic dishwasher detergent and some water in, and maybe a couple old nuts and bolts for agitation. Shake the thing.

 

[demarpaint]

I was reading, I wish I knew where that simple green and water work well for removing the Dex Cool slime. I wish I knew that before I flushed out the cooling system in my Buick. I used the Prestone T system and was pleased with the results, although I didn't have much slime. Next time I'm going to give Simple Green a shot. JMO

 

[LeakySeals]

Drain and fill with Peak global lifetime and RMI-25. The RMI-25 will puke out any excess dex into expansion tank. Clean and refill the expansion tank a couple of times. Drain and fill with Peak global lifetime in the spring. Done. Flushes itself.

 

[PhillyJoe]

On my 2007 Grand Prix, I just used the prestone T in the heater hose to give it a good flush, filled with water, ran it and flushed again before refilling. I didn't have any sludge,but with 75,000 miles at the time, I did it as preventive maintenance. This year I did my daughter's 2002 Gran Am (3.4 w/ the gasket issue). Drained, added a 1/4 cup Cascade dishwasher powder dissolved in a gallon of water, topped off with water, and ran that before draining/refilling/draining and refilling with Prestone.
Dishwashing powder in a car? Sure. It scrubs baked on lasagna off of china plates with no damage. It doesn't foam. It's safe for the environment. Who knew?

 

[Bgallagher]

Originally Posted By: PhillyJoe
On my 2007 Grand Prix, I just used the prestone T in the heater hose to give it a good flush, filled with water, ran it and flushed again before refilling. I didn't have any sludge,but with 75,000 miles at the time, I did it as preventive maintenance. This year I did my daughter's 2002 Gran Am (3.4 w/ the gasket issue). Drained, added a 1/4 cup Cascade dishwasher powder dissolved in a gallon of water, topped off with water, and ran that before draining/refilling/draining and refilling with Prestone.
Dishwashing powder in a car? Sure. It scrubs baked on lasagna off of china plates with no damage. It doesn't foam. It's safe for the environment. Who knew?


+1 The best way possible to flush the system.

Cascade has been used by Diesel mechanics for years for this reason. It safely scrubs, degreases and de-gunks and also doesnt foam. Effective and cheap cleaner