Radiator/Dex-Cool Flush

DEV1ST8R · August 20, 2005

I'm about due to flush out and change my Dex-Cool coolant. . .but I've never done it before. I'm assuming there's a drain plug on the bottom of the radiator? Just drain it out and hook a garden hose to the radiator and run it for a while? My repair book isn't helping me out much - I'm also wondering how many bottles of Prestone Dex-Cool I'm going to need to fill 'er up. And one last thing. . .I remember reading somewhere that it's not a good idea to use regular tap water with the 50/50 mixture - is that true?

Appreciate any help - THANKS!

(novice here)

tlocus · August 20, 2005

Hi BlacK1500,

I'm about to change mine as well.

...been looking at the haynes manual, looks like a lengthy process:

-Draining

Talks about draining radiator with drain plug and tube (it's on the right side of radiator).

Remove the 2 engine block drain plugs.

Remove the bottom radiator hose.

Reattach the bottom rad. hose and engine block drain plugs(says use permatex #2), etc...

-Flushing

*You might want to get a thermostat(or use your old thermostat) and a new gasket beforehand*

Says to remove thermostat but reattach the hose.

Remove the top radiator hose and insert a garden hose in the radiator opening.

Run water through system with heater on high. Water will flow out of the top radiator hose (that was removed from the radiator).

-Filling

Reinstall thermostat.

Reinstall any rad. hoses.

Add dexcool to purge tank run engine a little (says run rpm to 3000).

Keep adding coolant to purge tank until stays 1/2" above cold mark.

I also checked at the auto store and they had a 50/50 premixed version of Prestone Dexcool and also the reg. one.

I might go with the pre mix and not worry about the mixing and distilled water etc..

Someone else may want to add or correct me here

If in doubt get a manual (haynes or similar) it takes you through it step by step.

t

DEV1ST8R · August 20, 2005

Thanks man - I have a Chilton repair book and couldn't find the section on it for the life of me, but I found it today! I also found the table with the capacities. . .looks like mine takes about 13.5 quarts of coolant. I looked for the pre-mixed Dex-Cool, but didn't see any - that's the way to go.

Bish · August 20, 2005

The thermostat is a reverse poppet so it will open in reverse flow. The manual suggests Potable water for the cooling system. I have good water in my town so I don't mind using it. If you are really anal, you should drain the block, blow out the heater lines and use only demineralized water. Or get a flush but I don't like 17yr old kids working on my vehicles.

Having said that, this is what I do.

Disconnect upper radiator hose.

Connect garden hose sprayer to a hose fitting, piece of pvc, and a length of hose that fits on the radiator. I use clear hose so I can see the flow. You can't just blast away as 60psi of a garden hose can blow our seals. I run until the fluid shows clear.

Button it up and run her up to temp with the front and rear heat on high for a few minutes.

Repeat the flushing until clear.

Open radiator drain and make sure resevoir drains.

Pour in 1/2 cooling system capacity Dexcool (yes, I love Dexcool in a properly maintained vehicle).

Top off with water and run up to temp to bleed and recheck levels.

I even capture the first 8 gallons of coolant mix for proper disposal

mcreyaufmiller · August 20, 2005

When last I checked distilled water was about $.49 a gallon. It may have gone up, but the grocery stores normally keep it pretty cheap. This is good stuff to use when mixing.

asepgrad98 · August 20, 2005

Try to find "Havoline Dexcool". Its the real deal that GM uses

They sell it at NAPA

Bish · August 20, 2005

When last I checked distilled water was about $.49 a gallon. It may have gone up, but the grocery stores normally keep it pretty cheap. This is good stuff to use when mixing.

<{POST_SNAPBACK}>

It's not a cost issue to me. I'm just too lazy and I don't want to pull the block drains every time I do it

DEV1ST8R · August 21, 2005

Great! Thanks guys. Is there any difference between Prestone and Havoline Dex-cool? I'd assume if GM authorizes them both, they should be pretty similar huh?

Valsport · October 26, 2005

Anyone know where the block drain plugs are on a 5.3L?

Mr. Smith · October 27, 2005

Why would anyone pay the same price or more for one half the product That pre mix is marketing plain and simple to sucker in stupid people.

Havoline Dexcool at Wally World 9.88

Distilled water .57

I'm sure the premix is about the same price and a gall of dex. Anyone know what the premix crap goes for?

az'03Silverado · October 27, 2005

The pre-mix stuff is really only for topping off if your system gets low. If you fill your system up after a flush (unless you completely dry out every nook and cranny of your cooling system) you will have some residual water already in there. This gives you less than a 50/50 mix. Best to do like Bish said and fill half the system capacity with straight coolant and top off with agua.

jhm · October 27, 2005

Why would anyone pay the same price or more for one half the product That pre mix is marketing plain and simple to sucker in stupid people.

Havoline Dexcool at Wally World 9.88

Distilled water .57

I'm sure the premix is about the same price and a gall of dex. Anyone know what the premix crap goes for?

<{POST_SNAPBACK}>

Where I live, the pre mix is about $1.00 cheaper than full strength.

TonyMazz · October 27, 2005

In case no one has mentioned this......Do not mix DexCool wtih conventional anti-freeze !!! You will have a disaster on your hands as the dex will gel out and cause real problems.

If money is no object spend the money and have the dealer use there machine to reverse flush the system and install a fresh load of dexcool.

Cost should be around $100 bucks complete and then it's done for several years / miles...no fuss no muss...

They will remove your thermostat to flush properly and then have a new thermostat installed and volia you are done.

They really get the system clean...have been doing this on all my vehicles and now have two new vehicles.....

Just a thought....

AirForceAngler · October 28, 2005

Since I have to add anywhere between 1/2 and 1 gallon of coolant to mine about every 4000 miles, I guess I wouldn't really have to flush it out.

I keep a gallon of Dex and a gallon of distilled water in the garage, I just have to remember what I added last time.

I would strongly recommend the distilled water. Regular water can react and corrode areas where two dissimilar metals meet, i. e. aluminum and iron. I've seen heads that corroded so bad they had to be welded and resurfaced.

Bish · October 28, 2005

Since I have to add anywhere between 1/2 and 1 gallon of coolant to mine about every 4000 miles, I guess I wouldn't really have to flush it out.

I keep a gallon of Dex and a gallon of distilled water in the garage, I just have to remember what I added last time.

I would strongly recommend the distilled water. Regular water can react and corrode areas where two dissimilar metals meet, i. e. aluminum and iron. I've seen heads that corroded so bad they had to be welded and resurfaced.

<{POST_SNAPBACK}>

IMO the distilled depends more on your local water. The dealer and Helms manual say potable water which is drinking water. If your locale has very hard water, I would agree with the suggestion of distilled water. I have been using tap water on my Hoe for 135K and have yet to have any cooling issues. I replaced the water pump when I replaced all hoses last spring but I only replaced it because I knew I would eventually need to and since I was doing all the hoses, it made sense. My water pump was not leaking at all when I replaced it.