Thread: Dex cool questions

Originally Posted by DomHarris

my first question is can I add tap water to the rad, only till I flush it or buy more coolant,

Yes, but distilled water is recommended. With that being said, I've always just used tap water; if it's good enough for me, it's good enough for my vehicles. LOL

and the second question at 180,000 can I completely flush out the dexcool and replace with green coolant?

Yes. I'm not a fan of Dexcool and use regular coolant. You must flush thoroughly so all the Dexcool is out.

how to flush coolant:


remove the t stat, put the t stat housing back on, take the upper hose off the radiator, then push it down to the ground to a bucket or let it fly.


get your garden hose out, put it in the rad turn it on, then fire up the car, let it run till clear water pumps out the top hose.


then turn the hose off, run the car till no more water comes out the upper hose. then turn it off.


put your t stat back in, with new gasket, the upper hose back on.






now take 1 gallon of full strength green antifreeze, not the 50/50 crap. ( parts store cheap green is fine to use) dump the whole gallon in the radiator, fire up the car, fill the rad with hose water till its full. top as needed till its ready to be bled of air. it will burp and take coolant as the water in the block warms up the t stat opens up for a few seconds till cold coolant hits it and it shuts again.


now to bleed the air out, let it idle rad cap off till the fans turn on, (when the fans are on the temp is over 195 deg, the t stat is wide open) then open the bleeder screw on top the t stat housing a few turns till a steady stream of coolant comes out the hole, shut the screw, top off the rad. cap it.

Yup flush that crap out and use green. And I've always used tap water.

FYI, new dexcool does not have the problem of the old dexcool from back when these cars where made.

Just incase you wanted to stay with Orange Dexcool coolant.

Scott you forgot to mention to turn the heater on full blast.

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Originally Posted by Slick2500

Scott you forgot to mention to turn the heater on full blast.

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no need, coolant flow through the core all the time.

some times is worth flushing the core on its own just for the hell of it tho.

Technically you don't have to do that, the coolant flow is constant through the heatercore, the blender doors control when to provide heat based on the HVAC control settings.

On many older vehicles you have to turn the heat on though.

I've always been told to turn the heater on full blast because it is easier to flush out and bleed the system.

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Originally Posted by Slick2500

I've always been told to turn the heater on full blast because it is easier to flush out and bleed the system.

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its not 1975 no more. aka theres no on off valve any more.

Learn something new every day.

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remember before the dial or the short sliders, cars had the long side to side hot/ cold, or a mix of lever, there was a cable off the back that lead to a valve, when cold you were closing the valve, so it blocked off the core, hot opened the valve to let coolant flow through, why back in the day you were told to put the heat on full, the fan never did a thing either, just had to open the valve. aka to hot.

cant tell you how many of them i had to change, they used to fail when they got old and leaked all over the place.

today we get blend doors.