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How to flush radiator of 1999 Malibu?

ilovemymalibu's Avatar
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December 3rd, 2008, 4:56 PM   #1  
How to flush radiator of 1999 Malibu?

Hey all. I've been searching the net for several hours now and haven't been able to locate a proper guide on how to do this. The best I could find is how to drain it and refill but I don't think that is the same as flushing the radiator. My other question is that is it necessary to buy a radiator flush kit for this vehicle?

I apologize for asking such a basic question but I want to know for sure before starting. Thanks in advance.

EDIT: Spelling

wildman's Avatar
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December 21st, 2008, 1:38 PM   #2  
RE: How to flush radiator of 1999 Malibu?

I need to do this is well, so a start would be for me to put down what I have learned. These procedures are for a 97-2000 Malibu (Alero, Grand Am, and Cutlas?)
-=-=- Materials =-==
i) 2 (?) gallons of Dex-cool antifreeze (cooling system capacity listed at 3.2 gal)
ii) 2 gal of distilled water
iii) Permatex #2 thread sealant
iv) 1/4 and/or 3/8 tubing (4 ft. each)
v) Catch container at least 3 gal.
vi) thermostat gasket and o-ring (flush only)

=-=- Preliminary =-=-
a) Antifreeze warnings: Sweet taste attracts kids and animals, is deadly. Harmful to paint and skin. Flamable.
aa) Always dispose of antifreeze at a hazardous waste facility. Dumping antifreeze on the ground, garbage, or down the drain poisons the earth and is stupid. You and I or our kids will end up eating it in our fish or drinking it in our water.
b) Some of the coolant circulates through the interior heating system when turned to "heat", so you probably want to turn the heater on when replacing the coolant or flushing.
c). The radiator fill cap is apparently located under the radiator cover (4 cylinder only). If not there for a V6, see the bleed procedure in the =-Fill=- section.
d). Some people slam Dex-cool but it sounds to me like it is good stuff. I think I read where it helps lubricate the system so you should always use it, but that may not be true. Many warnings about mixing Dex-cool with something else, and I wouldn't do it. Prestone Long Life label says it will mix with any coolant, and can be used in any car, so it may be OK to use instead of Dex-coo. I plan on using 100% Dex-cool.
e) Radiator drain plugs are usually a wingnut type of screw that is hollow with a tube coming out that the coolant drains through.
f) Always mix antifreeze with the appropriate amount of (distilled) water to reach the mix % recommended on the antifreeze bottle. Usually this is 50/50. Some antifreeze is pre-mixed.
g) Use distilled water in the cooling system to avoid minerals in tap water that can cause scale buildup in the cooling system.

=-=- Drain =-=-=-
100. A cooling system cleaner / descaler can be added, and the engine run a while. This step is not needed if the cooling system has been serviced regularly. It is supposed to loosen deposits (scale) and rust, etc.
200. Use a large container to catch the coolant.
250. Make sure engine is cool before draining the radiator or opening the surge tank lid.
300. Radiator drain is on the lower right side of the radiator. You may want to attach a 3/8" hose to the drain pipe and deflect to a large catch container. You can use the square end of a 1/4 socket extension to open the drain plug. Manual says something about it drains out of the radiators rubber mount (then why the hose?).
400. Remove the surge tank cap to facilitate draining
500. When radiator is drained, move the container and remove the engine block drain plugs. There's one on each side of the block, and the manual shows it about half way down the side. It looks like it is an allen head screw or something.

=-=- Fill =-=-=-
100 Close the radiator plug (hand tight)
200. Replace the drain plugs, putting Permatex #2 thread sealant on them.
300. Do this bleed system (V6 only?): a) Use a 4 foot long piece of 1/4 inch tubing (I thought they said 3/8?) and run from the rad drain plug to an empty container. Open the drain plug.
400. Add new coolant (correct solution - see F above) to the surge tank until coolant runs bubble free out of the drain plug. Squeeze the upper hose a few times to help purge air from the system.
500. Close and tighten the drain plug and fill surge tank to the full-cold level.

=-=-=- Flush =-=-=-
100. The chemical clean, drain, and fill procedure will so some cleaning. If you want to do a more thorough cleaning, do a flush
200. Remove the thermostat and replace the housing without it (you may need a repair manual for this). My local garage wanted $200 in labor for this, but it does not look like it would be that hard to do.
300. Detach the upper rad hose from the radiator, and put a garden hose in the opening.
400. Turn on the hose and run until the water runs clear from the upper radiator hose you detached.
500. Put the thermostat back in, reattach the rad hose, and follow the =-=Fill=-= procedures.

Holy crap, this seems like a lot of work!

wildman's Avatar
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December 28th, 2008, 1:16 PM   #3  
RE: How to flush radiator of 1999 Malibu?

I completed this job yesterday and replacing the thermostat is kind of a pain. I would flush the cooling system without replacing it if possible. The thermostat is hard to reach, due to an exhaust pipe that crosses in front of it. Now I know why the garage wanted $200 to replace the thermostat! I was able to replace it, however, by loosening the coolant pipe and the exhaust pipe heat shield and working the thermostat cover until it slips out of there.

Some other notes:

I couldn't find the radiator drain plug to save my life [edit: I finally saw it by looking from underneath the car positioned at the front bumper and looking back. It is in the front of the radiator, at the bottom, on the R side of the car. Looks like you would need a square driver to open and close it], and ended up just taking off the lower radiator hose to drain it. This seemed to work pretty well. So no need for tubing, etc. I didn't remove the engine block drains and just relied on the flush. There is no thermostat housing gasket, just the o-ring, which is in effect the gasket (I used RTV silicone gasket maker on the flange just to make sure). My metric wrenches fit the bolts on this car better than my inch-scale tools. Do yourself a favor and buy a tool to remove those OEM hose clamps before you start. It is a continual struggle to deal with them, and my standard pliers are not up to the job. At least try to find a large plier that can open wide enough to pinch down the clamps. For some of the larger ones, I was able to use my vice grips to clamp them down, then screwed the adjuster bolt in to further close the jaws and loosen the clamp. I gave up on one and used a stainless hose clamp.

The only thing that I wish I had more input on is how to fill up the engine cooling passages when refilling. When I ran the car to op temperature, it sucked a lot of coolant from the surge tank, so there must have been some voids in there. This is a concern because the engine can develop hot spots near the air voids in the cooling passages before the thermostat opens up. Anyone have any insight in this?

wildman's Avatar
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December 29th, 2008, 12:35 AM   #4  
RE: How to flush radiator of 1999 Malibu?

Got it all back together but I thought I saw fresh orange coolant squeezing from around the corner of the intake manifold.

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