Dex-Cool Mud issues

1stdeuce · Aug 12, 2010

Ok, I bought an '06 last fall that had brown coolant, with about 120k on it. I had the dealer check it for blown head gasket, but it showed good. I assumed some fool put some green coolant in it, so I drained it out, flushed with fresh water a few times, and put new Prestone Dex in it. I also replaced the expansion cap and thermostats just to be safe. (It would run cold if you came off the throttle before the thermostat replacement, so I believe one was stuck slightly open.)

Now it's been 9 months, and I moved to Colorado. I'm noticing that the truck heats up pretty easily pulling what it should consider light loads. (6000lbs, mostly level, 65mph.) I'm wondering if I have a partially plugged radiator from the notorious Dex-sludge... Anybody know what might take this stuff out if I do?? I just got two bottles of radiator flush, and I'm going to run that for a few days to see what it loosens up, but I'm open to suggestion if there are better products. I've heard it's difficult to remove...

After reading so much bad stuff about Dex, I think I'll be putting the normal Prestone back in after I flush it out. At least then I won't have two kinds of coolant laying around... Everything else I own runs regular coolant with no issues!

dnewton3 · Aug 12, 2010

Simply put, DEX-Cool is known to turn if it get's exposed to consistent sources of air. I'm not a chemist but from what I understand, it has to to with the reaction of the OAT-based chemistry of the Dex-cool with oxygen. The other thing that seems to contribute to the degredation of the product is the time duration of exposure to the oxygen.

I also understand from some of my research that once the DEX-cool starts to go bad, it's kind of hard to reverse the problem. It tends to gum up into little balls and sit in low places and corners of the coolant passages. I'm not sure what brand of flush product you got, but I'd make darn sure to do it multiple times and hope for the best.

This is one project that benefits from a whole day in the driveway, doing it multiple times to assure the result. You might even go so far as to remove your rad and have it cleaned professionally at a shop. As for the engine itself, you can only hope the multi-flush does it's job in the driveway.

Another thing to note is that if you are going to convert back to the traditional ethylene-glycol based green stuff, you must get ALL the dex-cool out! That means pulling the two block plugs (one on the lower part of each side of the engine block) and draining the block completely. I've not done this, but heard it can be a pain.

Several people have posted here, and on other sites, that they have no issues with Dex-cool as long as they change it out every two or three years regardless of mileage. I realize that DEX Cool is supposed to be a 5 year, 100k mile coolant, but I simply don't trust it that far. I am on a routine to do a drain/fill every couple of years, thereby getting all that stuff out on a much more frequent basis. This is one example of where you'll actually get me to agree that changing out a fluid often makes sense, because the downside (if you don't do it frequently) is so terribly problematic.

HOpe that helps.

dinorex44 · Aug 12, 2010

Could also be a result of residual hard water after the flush. You can't get all the flush water out, and if your tap water is hard enough it can cause problems.

lilweeds · Aug 13, 2010

I have found is you drain it, then fill it with distilled water, run it for a few weeks, drain and fill again, and do this many times you'll get enough out to make the switch.

a bear · Aug 13, 2010

If you use distilled water and fill the expansion tank to the prescribed level (it is marked for a good reason) you will not have a problem running dexcool up to the recommended interval. Overfilling the expansion tank will significantly reduce coolant life.

turbo · Aug 13, 2010

I purchased my 2002 new in the fall of 2001. I replaced my Dex after five years and added a coolant filter. I change the filter once a year. I cut the filter apart and examine for debris and muddy coolant. Coolant aways looks great! Next year I will change the Dex again. As was mentioned, use distilled water mixed with Dex. I could not be happier. Great performance with Dex.

dinorex44 · Aug 13, 2010

turbo said:
I purchased my 2002 new in the fall of 2001. I replaced my Dex after five years and added a coolant filter. I change the filter once a year. I cut the filter apart and examine for debris and muddy coolant. Coolant aways looks great! Next year I will change the Dex again. As was mentioned, use distilled water mixed with Dex. I could not be happier. Great performance with Dex.

Turbo,

What coolant filter do you use?

cbiers · Aug 13, 2010

I drain/refill every couple years with dexcool. I just did it the first time on my '08 last month. I also did this on my '98 6.5 and it has 280,000 miles on it now and now troubles whatsoever from dex-cool.

1stdeuce · Aug 13, 2010

Well, I siphoned about four gallons out today, and other than being just a shade dark, it looks ok to me. I didn't find much evidence of mud in the radiator, but you can't see in it anywhere... I'm running mostly water now, and I'll probably drain a bunch of that out tomorrow and then add two bottles of flush and run that for a week or so. See if the coolant muddies up with flush in it or not.

I didn't mean this to be a Dex-Cool bashing, as I've used it with success in past vehicles, I'm still thinking that if I have problems, it's due to whatever happened before I got the truck.

I don't know what else would make it heat up so much, but it's pretty easy to overheat the thing with about 10k behind it on a warm day. Or about 13k on a very cool day for that matter, if the grade is long.

To make matters more interesting, I can't get the lower coolant hose to seal up... Started dripping a few thousand miles ago. When I pulled it apart tonight, the O-ring and little plastic ring thing fell out, so I put them on the radiator neck before I put the hose back on. Plastic ring, then O-ring on the neck, then hose over those... Sound right?

Thanks for the input!
C

dinorex44 · Aug 14, 2010

Thanks Trailwhale

DuramaxEric · Aug 15, 2010

The coolant filter is the best thing I Did Follow abears thread and you can't go wrong. My coolant stays as orange as the day it came from the factory. No issues at all and the first coolant filter change was amazing. The junk in the filter was unreal.

dinorex44 · Aug 16, 2010

Just ordered my base and filters from Fleet. Once it arrives I will start gathering the other parts and get it in. Seems like a great way to go.

1stdeuce · Aug 17, 2010

Well, I did one more fill and drain with water, and the coolant that came out was clearer than the first batch... I dumped in two bottles of Peak radiator flush, and mixed about a half a cup of liquid dishwasher detergent with a gallon of water and dumped that in, and then topped it off with water. (Figured the dishwasher detergent is non-foaming, and might help break down any oily sludge...)
I'll run this for at least the 6 hours recommended on the flush bottle, and then flush it with clean water till it runs out clear before I add any coolant of any kind... The coolant in the bottle is already turning a nasty brown color even with the limited drive time I have on it... I'm betting the radiator was all junked up, even though the coolant looked pretty good after I flushed it last time...

Coolant filter in my future, and probably some diesel antifreeze additive too, since all the HD diesels seem to call for it. ??

turbo · Aug 18, 2010

No aditive required, needed, recommended on the Duramax.

TaterWagon · Aug 18, 2010

Hopefully, all the flushing will take care of your problem, but if not, you might check into the engine oil cooler. Mine leaked oil into the cooling system and turned the coolant into a brown milk shake that took a total of eight flushes, 5 of which were chemical flushes, to clean up. It was quite a mess.

Take this for what it's worth... My truck is an '05, and I don't know whether there were any changes to the engine oil cooler from the LLY to the LBZ.

Dex-Cool Mud issues

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