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Old 10-29-2005, 09:57 AM   #1
jsup
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Default Dexcool Problems

A guy on another board was having a problem with no heat. One of the participants there is a top knotch ASE mechanic. Here's his comments on DexCool. Just FYI.

GM has ha major issues with Dexcool. It has a propensity to leak slowly past seals and gaskets (basically disappears) and the air gap between the fluid level in the radiator and cap becomes superheated, causing sludge to form. You will see this sludge when you pull the rad cap off, and it ends up in places like the heater core.

Dexcool tends to gain a positive charge faster than its green counterpart, which deteriorates thin metal parts like freeze plugs and water pump backing plate on the 4.3L.

But wait, there's more!

In a multi-million dollar study, GM quietly discovered that Dexcool was incompatible with the Nylon 6/6 that they were using in many parts of the engine and cooling system - gaskets, radiators, heater cores, etc. Rather than risk the tax credits they get from the Gov't for long-life coolant, they are quietly changing the plastics rather than the Dexcool. This is how I understand it.

Every chance we get at the shop, we recommend flushing Dexcool and going back to the tradional green antifreeze. The downside is that you are back on the 2-year flush interval, which is certainly better than letting the Dexcool run its course.

On newer GM vehicles that are still under warranty, it is in your best interest to flush and refill once a year with Dexcool. This will lessen the negative effects of Dexcool and not give GM an "out" providing a warranty situation arises with the engine or cooling system, by having green antifreeze. This is what I'm doing on my 03 Denali, and when the warranty runs out, the Dexcool goes.
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Old 10-29-2005, 10:24 AM   #2
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Default Dexcool Issues

The various issues surrounding continued long-term use of Dexcool has been discussed quite lot on the forum and on the Internet in general. It seems there are several factors at work that can initiate a failure of the coolant and with neglect eventually will cause sludge and plugging in radiators and heater cores. If there is conclusive proof I have not found it yet but there are a lot of suggestions and theories out there about what the actual failure mechanism is. Some have suspected a chemical reaction with the so-called GM cooling system pellets (stop-leak) which GM actually recommended and which were included in the original factory fill at one time but later discontinued. Others have said it is very important to check often and make sure your cooling system is topped off and completely full with no trapped air inside. The findings mostly agree with your comments that the coolant is disappearing somehow and allowing air to enter the system which initiates the failure process. I believe Dexcool is less abrasive than the earlier green Ethylene-Glycol coolants and engineering says waterpump seal life is extended with Dexcool. I have it in my 04 and 96 Corvettes but I will make sure the cooling system is always full and topped off and flush and refill periodically.

Regards, Greg
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Old 10-29-2005, 10:24 AM   #3
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jsup, them's heavy charges re Dex and GM! Wow. Can "they" do that and gety away with it?

I think we've got some more GM peop on this forum; it sure would be nice to get a little corroboration on this matter. Anyone else hear/read about this kind of sucky situation with Dex vs. Green stuff?

Time to go change my antifreeze, or whatever the hell it is...

Thanks for the headsup, jsup, really.
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Old 10-29-2005, 10:40 AM   #4
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Quote:
Originally Posted by LT4CompYell
jsup, them's heavy charges re Dex and GM! Wow. Can "they" do that and gety away with it?

I think we've got some more GM peop on this forum; it sure would be nice to get a little corroboration on this matter. Anyone else hear/read about this kind of sucky situation with Dex vs. Green stuff?

Time to go change my antifreeze, or whatever the hell it is...

Thanks for the headsup, jsup, really.
I have a radiator buddy.....he uses the green stuff, good enough for me...Larry
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Old 10-29-2005, 10:52 AM   #5
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I do not use Dex-Cool but do have a question about the "air space". A cooling system is a closed loop system. As coolant heats it expands pushing the now excess fluid into the reservoir. When the system cools the coolant contracts creating a vacuum which pulls coolant from the reservoir filling the cooling system. How is an air space created that would exist more than single heat-cool cycle? I think I would be more concerned about the effect of a dissimilar electrical charge.
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Old 10-29-2005, 10:53 AM   #6
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My brother has a '96 GMC Jimmy, which has the Dexcool in it from the factory. He has had the sludge, and heater core plugging problems!
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Old 10-29-2005, 12:16 PM   #7
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Default Disappearing Dex-Cool

I recently learned about the disappearing Dexcool problem many are reporting so I checked my 96 car and sure enough the reservoir was empty and the expansion tank low (had air in it). I did the Optispark and waterpump last year and flushed and refilled with new Dexcool so assumed everything was OK until I checked it and discovered I too had disappearing Dexcool for whatever reason. I park in a garage and have not seen any leaks and temps have been normal while driving so did not suspect a problem. I will check more often and top off as needed now, however. It would be nice to understand why this is happening and what the mechanism is behind the disappearing Dexcool. If it's leaking internally, where does it go? The oil stays clean, does it simply vaporize?

Regards, Greg
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Old 10-29-2005, 12:30 PM   #8
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Don't know nuthin about Dexcool, but I did a re-fill of coolant yesterday on a 1968 Chevelle and the coolant container said,
"can be added to any color coolant". Its a Prestone product.

If this coolant works with any color coolant it could replace iether one probably without a problem.

Or a combination of the two would probably work.

It appears to be somewhere in between the Dex and Green.
It is green in color.

Personally I don't trust any new when the product thats beening replaced is a proven product. Better, hmmmmmmm.
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Old 10-29-2005, 04:12 PM   #9
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I've never had any problems with DexCool in either of my 96 Vettes or my 98 Cadillac... Those cooling systems are 7 and 9 years old...
__________________

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Old 10-29-2005, 04:33 PM   #10
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I changed the dexcool in my wife's 2000 Buick. I couldn't believe the amount of sludge in the system. Went green and then had to repeat it to get rid of all the sludge.
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Old 10-29-2005, 04:48 PM   #11
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Quote:
Originally Posted by quantum-theory
I changed the dexcool in my wife's 2000 Buick. I couldn't believe the amount of sludge in the system. Went green and then had to repeat it to get rid of all the sludge.


I got a 01 Pontiac Grand Am that sludge magically appeared with only 40K miles and now by 03 GMC 2500HD as a suspicious ring around the reservoir container at get this, 3000 miles, and it stays in a climate controlled garage it is my 2nd baby, 1st is the Vette.
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Old 10-29-2005, 05:57 PM   #12
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I've never used Dexcool. Just the green Prestone pre-dilluted stuff that lasts two years. I just did a radiator flush-and-fill as part of my 92's "winter stasis" procedure.
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Old 10-29-2005, 06:09 PM   #13
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My wife has a DEXCOOLed Impala and every 6 months I have to remove the reservoir and clean it to remove a sludgey funk so that I can see the coolant level. I have been doing this since the car was about six months old. I have even flushed and refilled the car once, I believe that DEXCOOL sucks and once the 36 month powertrain warranty is gone, so is the orange crap. In fact I spent this morning performing the reservoir cleaning on the wife's car. I am looking forward to getting two years out of coolant.

I brought the car back to the dealer a couple of times about the coolant and they tell me to (remain calm all is well)

Once again IMHO DEXCOOL sucks!

Mike
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Old 10-29-2005, 07:01 PM   #14
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As you said.. decool is crap. I had it in my 97 blazer in which my waterpump crapped out on me 3 times. My radiator just went along with my intake manifold leak. They now have come to their senses that the dexcool has done my truck more harm than good. they got rid of it and used the green coolant now. I am much happier. Just got it back this week. We will see how long it lasts now. On a side note.. I got a new 2005 Xterra and won't be using the blazer as much. That was the whole reason I got it.
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Old 10-29-2005, 07:02 PM   #15
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Default Dexcool- Some love it, Others hate it!

Dexcool will remain a mystery for now I guess. The experience with Dexcool varies as much among us here as it does in reading through the many historical accounts about it both good and bad on the Internet. Some folks are constantly fighting against a persistant sludge attack, always cleaning their radiators, tanks and caps only to see more sludge return again later. Reporting it to their dealer is usually met with indifference by an uncaring patronizing dealer service manager. Others use the stuff for years giving it little or no attention and their cooling systems remain as clean as a whistle and trouble free. Why do some folks have nothing but trouble with Dexcool and others remain trouble free apparently experiencing the long coolant life the stuff was engineered for and promised to deliver?

Regards, Greg
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Old 10-29-2005, 10:15 PM   #16
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I had the disappearing act with the Dex-Cool in my '99 Silverado. It seemed like every month or so, The recovery tank would go dry. Couldn't find out where the coolant was going and there weren't any leaks. Then it stopped. I wound up replacing the water pump too (leaked at the weep hole). Strange.
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Old 10-30-2005, 08:35 AM   #17
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The word around here is it will eat gaskets also
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Old 10-30-2005, 11:32 AM   #18
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get it green again
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Old 10-30-2005, 12:07 PM   #19
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i don't have enough technical knowledge either way.. just common sense. since there are no issues with green, and maybe or maybe not issues with orange, and i really don't see any advantage to orange, why even use it??
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Old 10-30-2005, 02:13 PM   #20
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Quote:
Originally Posted by bdvdvh7
i don't have enough technical knowledge either way.. just common sense. since there are no issues with green, and maybe or maybe not issues with orange, and i really don't see any advantage to orange, why even use it??
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Old 10-30-2005, 02:13 PM
 
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