Ok so, I sold my Ford Ranger and purchased '99 Astro Cargo van for my business. I got one with no windows on the side nor back so I can display my business name/graphics.

When I was checking it out, I checked just about everything including oil levels and condition, tranny fliud and condition, brakes, shocks, frame...everything I could think of.......well except one thing the radiator. To my horror after I bought it, I pulled out the overflow container and found this brownish colored sludge in it. It was thick and chocolaty.

My first thought was oil in the fluid which would lead me to be a blown head gasket or something. Rechecked the oil and tranny fluids, they still look perfect.

So I began to try and flush it all out and then I noticed red fluid about the color of tranny fluid in the radiator floating to the top. SO now I am thinking that the tranny cooler lines have cracked inside the radiator causing a one-way leak(tranny fluid still perfect).

So THEN, i do some research and find that the '99s had Dex-cool which is red in color. I also found that if someone tries to put the green stuff in it,it will trun it to a sludge like I have seen.

So the advice I need is from people whom have had experience with Dex-Cool and get opinions on if I should try to just flush the system and put Dex-cool back in or should I replace the radiator first then install Dex-Cool? I can't tell if the red fluid I am seeing is old dex-cool or Tranny fluid.

Also, I read that the green stuff is very abrasive and could do some serious damage to the gaskets and such in the motor. Is there a possible "conversion" out there that the previous owner could have done to it?

I got months and months of red slime just from corrosion alone on my 85 when I bought it.

Get the Prestone that is compatible with both, and put that in. That's what I do on my truck that the prev owner put dexcool in.

I'd still want to blast the system out though. Pull the tstat and flush it with a garden hose. Radiators are cheap, but hey if it doesn't overheat, and the water comes out the petcock clear eventually, why spend more than you have to?



Basically dexcool sucks if it gets exposed to air. It's touted as low maintenance coolant, but you have to make damn sure the overflow always is at the proper level.

I think the class action against GM was unsuccessful. Technically they provided a working product, but it was overly sensitive to neglect vs. the green stuff. Probably a poor choice on their part. The engineers should take more into account than lab tests IMO.

I never had to use the stuff but I would assume that a good flush would get things going well again. I would say its your choice of what to put back in there though.

Okay, this is going to be kinda long, but it is my experience with Dex-Cool.
We had a 1998 Pontiac Trans-Port Van a few years ago, had 24K miles on it when I bought it. Due to circumstances having to take my daughter to Knoxville (about 90 miles one-way) two to three times per week, we were putting a lot of miles on this van. At about 85k, I noticed the "low coolant" light coming on intermittently. I kept check on the coolant level, and added when necessary, all the while wondering where it was going......evaporation.....? The van ran just fine thru all of this. At 93k, while on the way to Knoxville one day, the van kinda "shuddered", the check engine light starting flashing, and the motor started missing.....really badly.
I'll bypass the rollback ride and how hard it is to get into the motor in the van. When I took the motor apart, the intake gaskets had disentigrated....literally! The "plastic" part of the gasket that holds the silicone "seal", was "eaten" away. Research let me know that Dex-Cool will mix with motor oil....with dire consequences. The small amounts that had been leaking had allowed the cam bearings to wear out, to the point that the cam broke in half! The block was even ruined....cam bearing bores were junked!
Fast forward again.......I bought a motor with 60k from the junkyard......but before installing it, I decide to at least look at the gaskets.........and sure enough, the intake gaskets were being eaten away around the coolant passages. I of course replaced them, sealed the motor up, flushed the coolant system, and filled it with GREEN GLYCOL COOLANT, and drove the van for another 50k before I traded it. I would never put Dex-Cool in anything I own again, and if you Google Dex-Cool problems, you will find that GM knows it has it's problems in some applications, but will not do anything about it. At one time I had pics of the gasket damage that I sent to GM, but I'm not sure if they still exist on my computer. The "sludge" you found was not the result of mixing Dex-Cool with regular Anti-Freeze.....they will mix just fine, but mixing them destroys their corrosion resistance.......what you found was the result of the Dex-Cool running with air in the system. Once again, Google it and it will back me up.

If I sound bitter over this, I am. If you had been through what I was, at the time it was happening, you would understand. Hope this helps, and I hate to ever sound like I "know it all", but when it comes to this stuff, I lived it.

I'm still using the red stuff (dex-cool) with, so far, no ill effects. Its been almost five years now. Living on borrowed time???

OK guys, thanks for the input.

BUt what I read was that you could not use the green anti-freeze in a system that was built for the Dex-cool. Is that true?

If not, can I just do what you did and totally flush the system and use the green stuff?

Your suppose to put distilled water in to keep the inside of the cooling system cleaned but if your flushing it out with the hose pipe, wouldn't that be defeating the whole purpose? Better to poor 5 gallons of bottled water thru it instead?

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I used "off the shelf" radiator flush (got it at Advance, can't remember the brand), completly flushed the system, and ran the van for 50,000 miles with no ill effects. Now, on top of that, my wife's 2004 Grand Prix now has 75k miles......I flushed it and changed to Green coolant just after the 36k (factory warranty) mark. It's been fine since. I plan to do my Colorado PU the same way once the warranty is gone on it.

One thing I noticed on the van and my wife's car.......it ran a bit cooler once I changed to the green coolant.......not a lot, but few degrees.

My experience says you can flush it and change it, but if someone else knows otherwise, I'll listen, too.

Thanks! I may just do that!

I may still have a tranny leak inside the radiator. I guess I will flush it real good and see if I still see red.

Just run the prestone yellow through it for awhile man! Then in a few years you can start putting the green stuff in exclusively.

You will want to change the radiator cap to a model that has the spring-loaded closed drop down center.

See this link:

http://www.imcool.com/articles/antifr ... lant/dexcool-macs2001.php

I had poor experience with the dexcool in my 2003 monte carlo. The intake gasket went bad at 69,000 miles. Cost me quite a bit to get it all repaired, even with the extended warranty. I did a lot of research after it happened and found thousands of complaints online. Personally I would flush the system very well and put in regular antifreeze. I would never have it any of my cars now.

Matthew

"Regular" antifreeze isn't the best option. I agree with CC that the Prestone that mixes with both is the BEST solution.

DexCool can contaminate a good system even with a good flush. It gets into gasket surfaces and will leach out a bit. However, a thorough flush should mitigate the problems.

Also, Brut, replace the damned overflow tank! It might not be worth fixing. The radiator may be salvagable, take it for an ultrasonic cleaning.

Also, Brut, when you drain, remove the knock sensor(s). They are the block drains. I would consider removing the t-stat and the knock sensors and running a hose into the motor.

Considering the intake gasket issues, I would consider that job, too. I wonder if driving it for a week on plain old water would not be a bad idea... really work the goo loose.

Is there any warrantee on this thing? Or was it a private sale?

NC Kid - when cleaning out a cooling system, you can use tap water. The pressure will force more crap out and when you drain, the majority goes with. The small stuff left behind won't ruin the new coolant mix. You also need more water than 5 gallons, so why waste the good stuff?

Thanks again for the input.

Andy, no this was a "As-IS" sale. The thing has 185K on it! iT has been very well taken care of. The tranny was rebuilt by the car lot. The guy that owned it just traded it in because the tranny went out.

I have never had experience with Dex-Cool, so I am clueless about it. The stuff that has come out of my radiator has an "oily" base as it causes everything to bead up and I can see a rainbow spectrum on my driveway for its residue.

I am still thinking that I have tranny fluid leaking into it somehow.

All coolant I've every messed with had an oil feel to it. It's really slippery on pavement.

it is. It has something to do with the nature of ethylene-glycol.

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Yes, there is absolutely no problem with converting it to ethylene-glycol. Do your flush and refill with the green and distilled water. I also add one pint of Pencool 3000 to a four gallon system. It has additional protective chemicals that prevent interaction between dissimilar metals, neutralizes and prevents corrosion and electrolysis, etc. I've torn down diesel engines with more than a million miles on them that had good cooling system maintenance and which used Pencool as part of that maintenance. The water jackets and wet side of the cylinder liners would not only be corrosion free, but would still have the appearance of freshly cast metal, light gray. I've also torn apart ones that were neglected with only a fraction of that many miles in which the block would be severely damaged and the liners badly pitted, sometimes all the way through. Proper cooling system care is as important as regular oil changes for a reliable, long-lasting engine.
Dexcool and other extended life coolants (which are all the same basic formula with different additive packages spec'd by an engine or vehicle manufacturer) are simply too sensitive to contamination. For example, adding as little as 10% of system capacity of tap water pretty much renders it's additive package ineffective and the damage begins.

the penncool 3000 sounds like neat stuff. never heard of it. generally available?

Great advice!

Update: I bought a flush kit and flushed it out real good.I drove it around for a while and once it cooled, I opened the radiator cap to see if I still saw any red or chocolate milk, and I saw pretty much just water. SO I may try to flush it a couple more times and then do ethylene-glycol with the additives.

If I do need a new radiator, I can get a new one for $99.00. My sister is the manager of a Pep-Boys and she gets a great discount!

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Check with your local part stores. It should be available from any store that carries Penray products, an old established name in automotive chemicals. Make sure and specify Pencool 3000 (not 2000, etc.) It's the most suitable formula for our purposes.