View Full Version : Dex-Cool Antifreeze Problem

02-17-2005, 12:37 PM
Has anyone had a problem with Dex-cool Antifreeze (the orange stuff). My wife's Chev Blazer has it and there is a paste like crud in the cooling system. A radiator shop has said that can happen if air gets into the system. The problem is cleaning it back out. We are trying flushes with limited success. Next step might be removing the radiator. That, however, won't get the crud out of the heater and engine. Ideas???

02-17-2005, 02:20 PM
No real suggestions but thanks for the heads up. I'll be sure to never use that stuff now.

02-17-2005, 03:17 PM
Cascade dish washing detergent works wonders for such a problem. Its a heck of a mess to dispose of properly though. In a former life I worked at a Chrysler dealership. A number of customers had the same problem with various vehicles (mid 90's) and the Cascade suggestion came right from Chrysler. It worked very well, however, we had to use Saftey-Kleen to dispose of what came out of the engines.

02-17-2005, 04:36 PM
How much Cascade would you put into the system?

02-17-2005, 08:15 PM
Hmm, I've heard that Dexcool works excellent unless some kind of non- Dexcool collant is added to it.

02-18-2005, 12:20 AM
checking the search engines, I find there is a class action law suit against GM regarding problems with dex-cool. In my case I am fairly certain it wasn't contaminated with another type of antifreeze. But more to the point, why would you want any antifreeze in a car that can turn to sludge for any reason. Still my problem remains, how to get rid of the sludge w/o spending an arm and leg by removing the radiator, heater, engine, etc.

02-18-2005, 02:29 PM
My 2000 Buick Century, as all GM's came with Dex-cool. It is warented for 5 years. I have 170,000 km on it now and had it tested when I had the brakes done last month. I was told by the mechanic at GM that the fluid is absolutly fine and could easily go for another year or so, and since I havn't had to change the thermostat yet, I may as well wait.
There is a bit of scum around the overflow, but nothing to worry about.
I will definatly replace it with the same when I do.


02-18-2005, 03:57 PM
Hi Shorn,

Chrysler never did give any specifics about concentration. What we did was drain the system of coolant, mix up a batch, fill the cooling system, and run the vehicle (not drive) up to temp, drain, flush, repeat. Worked like a charm.

02-18-2005, 04:45 PM
Steve99, I will give that a try and see if it cleans things up.
KLUTZ, Obviously, this problem doesn't affect every GM car, although it seems to hit Blazers and s-10 trucks more than passenger cars. After more research it appears the sludge develops quickly if air is allowed in the cooling system. So how does the air get in the cooling system? Some Blazers have developed leaks in the intake manifold gaskets (Is that a design problem or a coolant problem?). Others have had failed radiator caps that allow air to get into the system (Is it a bad cap or does the sludge stop the cap from sealing properly and let in air?). On my car the overflow tank had water/coolant in it and was checked regularly. However, there was a small shortage of coolant in the radiator itself, although the car only registered hot once right when we discovered the problem. Of course, you are not suppose to remove the cap if the car is warm, so perhaps the radiator itself wasn't checked as frequently as the overflow tank. I don't know why the system lost fluid, maybe a bad cap, but it did. In any event the sludge has ruined radiators, heaters, engines, and automatic transmissions (transmission cooling lines run to the radiator and guess what?? get plugged by the sludge). At this point I hope to be able to flush it out and that no real damage has occurred. However, a google search has provided me with enough horror stories that I may want to look for another car. Interestingly, my 2000 S-type Jaguar uses dex-cool antifreeze without any reported problems that I know of. So perhaps this is limited to some GM products due to a varity of causes. From what I hear, GM is stonewalling on the issue (remember the side saddle gas tanks in GM pick ups) especially if the vehicle is out of warranty. There are at least eight class action law suits filed.

02-19-2005, 08:05 PM
Dex-cool is notorious for creating that nasty brown sludge. Happened on my wife's Oldsmobile.

A good radiator flush should get rid of it -- and the worst places are up near the cap.

02-22-2005, 01:27 PM
Various flushes removed some of the sludge, but in the end, I had to pull the radiator and have it rodded out. My radiator shop said it was still about 30% blocked. Anyway, since I pulled the radiator myself, the cost wasn't too bad. I did not refill the system with death-cool (sorry dex-cool), but went to the green stuff instead. Bottom line, if you own a v 6 GM engine, watch the coolant very closely.

Super 7
02-22-2005, 02:17 PM
I have had it in one of my Vanagon's for 2 years next month. No problems yet, but who knows? Its phosphate and Silica free, which is what VW recommends.

Vanagons are notorious for cooling system corrosion.