Before I even run the Blazer I bought, I would like to know if it would be wise to flush out the DexCool and put in some of the green stuff. DexCool was what killed my dad's '90 LeSabre Custom, and I would like to avoid that on my Blazer because the engine in it is a fairly low mileage engine, and ran like new when it was last driven. LIM gaskets were done at 148k and it has about 149.5k right now. The plan would be to totally flush the radiator and heater core (at least running on water for a week or 2), and then totally flush the block and use the green coolant. I've seen the way DexCool clumps up and clogs coolant passages when mixed with anything.

 

I did it to mine when I first got it, after the heater core plugged up(an issue I had repeatedly on my previous blazer) not only has it not caused an issue, but I haven't had a plugged heater core since!

From my understanding of it, it will be non issue as long as you flush everything very well with clean water.(like you said you were planning)

I have seen people end up with thick goop from mixing the 2 coolants, though.

 

About a month ago I did an experiment with new Dexcool and one of the new green coolants that says it is compatible with Dexcool. I mixed about a half a cup of each into a small pyrex dish and added a about another cup of water (50/50 mix right?) and let it set for a couple days.

Nothing happened. I even put a strip of aluminum in there to see if there would be a chemical reaction with it. Again nothing.

I guess to be thorough I should have also put a piece of iron and then heated it all up to about boiling for a while to see if another reactions occurred.

When I did this I had assumed my "green stuff" was the classic type and I wanted to observe the precipitation of the brown-goop but turned out I found out that it is likely these new green antifreezes can be compatible with the Dexcool.

From what I've read here and elsewhere, the Dexcool is fine IF it is the new version of it and if there is no air is the system. Then again it might have been the older Dexcool that had trouble with the air.

Do the '93's have the same history of the bad LIM gaskets? If so, you might want to do those right away.

 

As for the DexCool conversion, it's already been done. I didn't notice. And as for the LIM gaskets, yes they go bad just as easy

 

my heater core is definitely clogged. very little heat in the truck. apparently muriatic acid (in small amounts) can dissolve it easily.

 

Bad idea. Are you familiar with muriatic acid? It's just an old name for concentrated hydrochloric acid which can instantly take the skin off your body. If you start to add water to muriatic acid, it generates so much heat that it will immediately splatter. With concentrated acids you always add the acid to water to avoid this. You have been duly warned! Better yet - don't put hydrochloric acid in your cooling system - period.

 

Well, I wasn't going to try it. I've just heard that it works. As of yet I don't even have the blazer off the trailer so I can't really do anything with 5he cooling system anyway

 

just trying to save you some grief.

What I don't understand is why both your 1993 Blazer and your Dad's 1990 LeSabre would be using Dexcool. It didn't come out until 1996. Are you aware that Dexcool is not for use in vehicles with copper containing radiators or heater cores? I do not know what the case is for you but my 1990 Pontiac had a copper radiator. The organic acids in Dexcool which serve as protection against corrosion react with the copper and are depleted. Furthermore, organic acids are not compatible with the silicates in old type antifreeze. They react with each other and the result is a coolant with drastically reduced corrosion protection. So it is very important to not mix Dexcool with green (during an incomplete flush). The only advantage to using Dexcool seems to be extended coolant life but only if there is no mixing and the coolant is kept full as air also reacts with organic acids when hot. If you deplete the corrosion protection it doesn't matter which type is used, you end up with brown mud.

 

The reason the LeSabre had DexCool is because it was brought back to a GM dealer in 1998 because of cooling syste.m failure. Somewhere along the lines when they repaired it, it ended up with DexCool. On the blazer, I had assumed that was what was in there because that's what the owner told me.

 

Sounds like your father's Lesabre had cooling system problems before the Dexcool was mistakenly added, probably without flushing. Idiots work in dealerships too! Sounds like you probably have a mix in your Blazer as well.

To me, it seems that Dexcool itself was not the cause of your problems. It was mis-use of Dexcool. Dexcool used properly works just fine (except as we all know the problems on original plastic intake gaskets with original Dexcool). But the need to not mix it with old style antifreeze and to keep air out of the system has given it a very bad rep.

I agree that your 1993 should not have Dexcool in it - but not because Dexcool is inherently bad. Just make sure what is in there now is completely flushed out. That may or may not be possible if it is gunked up too much.