My son just bought his first car, a 2006 Buick Lacrosse. Sweet deal. Little old man-driven, 68K miles $800 in maintenance put into it a few months ago, new tires and clean all for....$1500!
Anyway, it has Dex Cool. I have very little experience with GM stuff, quite on purpose. I have only heard horror stories about the stuff. Well, sure enough he drives it Monday and tells me he doesn't' have heat. The temp gauge is only 1/2 way to normal operating temp. So he and I swap in a new t-stat. The coolant in the reservior looks ok I guess, it's hard to see anything down there. Inspecting the inside of the motor below the t-stat looked great. Coolant was orangish, not cloudy, seemed fine. We topped it off with Dex Cool. Temp gauge goes almost to NOT, but he still has just a little heat. The temp at the dash outlet is 80 F. That's 40 degrees lower than I'd expect. I measured temps at the heater hoses going in and out of the heater core. There was about a 40 degree difference between the two.
I guess it's time to flush the heater core. Should we have the entire system flushed to get rid of dex cool and just go with glycol mix? Is Dex Cool really the devil?
flush it and refill with dexcool. We have multiple GM vehicles in the fleets with 200+k miles with no issues. Most dexcool issues happen when people top off with incorrect fluid or they get an air leak.
bobzilla said:
flush it and refill with dexcool. We have multiple GM vehicles in the fleets with 200+k miles with no issues. Most dexcool issues happen when people top off with incorrect fluid or they get an air leak.
What do you mean an air leak? And what happens?
Air gets into the system, weak clamps, weeping pump, any kind of leak. The air mixes and created a chemical reaction that turns it corrosive. If there's no leaks, and it doesnt' need topped off then you're GTG
Yep, what they said..
And a clogged heater core is just going to happen on a little-driven, 15 year old car.. As much as I love to blame GM for stuff, that just kinda happens.
Now's a good time to plug in an OBDII reader an make sure that the thermostat is working properly. On the dash guage, it's probably more of a go/no-go where anything from 120-220 reads "okay" in the middle, but with an OBDII reader and the Torque App, you'll be able to watch what the coolant temp itself is actually saying. If you don't have one, just search your favorite online retailer for ELM327 in bluetooth or wireless, whatever creams your twinkie.
In reply to DrBoost :
I got 371,000 miles on my trouble free pickup with Dex-cool. Original everything. Never a problem.
In reply to frenchyd :
And that just might be your saving grace, those miles. Sounds like a little-old-person-driven car, combined with Dex is a bad thing. In my opinion, that's another thing GM got wrong. If you have a car and driving it 4,500 miles a year causes the cooling system to clog, that's bad news. sounds like I'm going to flush the heater core (it's 7º F degrees outside, yay!) to get him heat, then in the spring give it a Dex-ectomy.
Thanks all for your info. I appreciate it.
The thing is, unless you are in the habit of checking coolant level regularly, it's pretty easy to get air in the system. In the case of my wife's car with just under 60k miles on it, a slowly weeping water pump allowed air in, which causes large quantities of a brown mud to precipitate out of the Deathcool. She first noticed it when the temp gauge was running just a smidge higher than usual. By then, enough passages were blocked that the plastic intake manifold warped. Two grand to fix at the stealership.
I would never run the stuff in anything I owned.
In general, most coolant problems I see (brown mud included) come from one of a few things:
- Ancient coolant that hasn't been changed and is well past its use by date
- Someone topping off the system with a different coolant that's not compatible, causing either brown mud or a jelly-like goo plugging the heater core
1988RedT2 said:
The thing is, unless you are in the habit of checking coolant level regularly, it's pretty easy to get air in the system. In the case of my wife's car with just under 60k miles on it, a slowly weeping water pump allowed air in, which causes large quantities of a brown mud to precipitate out of the Deathcool. She first noticed it when the temp gauge was running just a smidge higher than usual. By then, enough passages were blocked that the plastic intake manifold warped. Two grand to fix at the stealership.
I would never run the stuff in anything I owned.
Disclaimer: Not defending death cool here, but I had to replace the heater core on my 05 Chrysler Town and Country that came from down in Southern VA. It had a lower-than-yearly-average amount of miles on it. My other 05 T&C's heater core was still fine when I sold it @ nearly 90k more miles.
I know, it's anecdata, but still, just sayin.
Peabody
UltimaDork
1/28/21 3:53 p.m.
The vast majority of GM cars with Dex will never have a problem, but there are so many on the road long term, that even a small percentage looks like a big deal
Peabody said:
The vast majority of GM cars with Dex will never have a problem, but there are so many on the road long term, that even a small percentage looks like a big deal
It's important to consider the timeframe we're talking about. The author of this article
https://ricksfreeautorepairadvice.com/is-dexcool-bad/
claims that "The problem was so extensive that it affects just about every 3.1 and 3.4-liter made in the late ‘90’s and early 2000’s." My wife's car was a 3800 that was maybe 3 years old and daily driven. This is not a small percentage and it was kind of a big deal.
Backflush the heater core, flush and refill the cooling system with Dexcool/distilled water, replace any lousy-looking hoses and clamps. The car's 15 years old, and it's possible that it's never been flushed.
I run it in my Silverado, my business partner's Tahoe, and both Colorados, one of which is now in my personal fleet. The Colorados have close to 300k on them. The Silverado has 220k, the Tahoe 180k. No issues with any of them.
I also had a Venture with the 3.4. It sludged up when the lower intake gaskets started weeping at 120k. It was fine until that happened. When I did the gaskets I converted it.
My Suburban had already been converted when I bought it.
I won't go out of my way to get rid of it but I won't keep using it if I have to drain the entire system for a repair.
Something to check if you are losing water is the belt tensioner. Seriously, they route coolant through it and the pipes can get bad and leak. It's not a terrible job to replace it.
BlindPirate said:
Something to check if you are losing water is the belt tensioner. Seriously, they route coolant through it and the pipes can get bad and leak. It's not a terrible job to replace it.
Wait what! They route coolant INSIDE of the belt tensioner!?!? Surely you jest!!
He's not kidding.
If I bought anything that had Dex in it I would flush everything as well as I reasonably could and switch it to classic green stuff and have it over with. "Most of the time it doesn't turn into bubblegum" is accurate but why wait for it to happen? Do it in the spring when it's nice outside. General maitenance.
DrBoost said:
BlindPirate said:
Something to check if you are losing water is the belt tensioner. Seriously, they route coolant through it and the pipes can get bad and leak. It's not a terrible job to replace it.
Wait what! They route coolant INSIDE of the belt tensioner!?!? Surely you jest!!
If its a GM3800 engine, check the coolant elbow near the tensioner. Black plastic is factory, silver metal is the better aftermarket version.
This reminds me the coolant in my 08 Mustang is original. I don't care what is in it now, it needs to get replaced.
What did Ford use?
akylekoz said:
This reminds me the coolant in my 08 Mustang is original. I don't care what is in it now, it needs to get replaced.
What did Ford use?
Should have been the Motorcraft Gold HOAT coolant in those years. It's just re-branded Zerex G-05. Pink Mopar HOAT is the same stuff as well, just dyed differently.
Berkley dexcool. I've seen nothing but problems. I'd flush that E36 M3 day 1.
Does anybody know the upside of using Dexcool over universal type coolants? Just curious if there's a specific reason to stay with it. I flushed mine and replaced with universal when I did the first coolant flush.
WillG80 said:
Does anybody know the upside of using Dexcool over universal type coolants? Just curious if there's a specific reason to stay with it. I flushed mine and replaced with universal when I did the first coolant flush.
Allegedly, the big one was "more environmentally friendly" and less toxic.
The other one I've heard is that it's easier on cooling system components and prolongs water pump life. I'm having trouble reconciling that one with "water pump on vehicle goes bad inside of three years/60,000 miles."
In reply to 1988RedT2 :
Completely agree Red. If there's not a huge cooling efficiency increase, I don't see the risk/reward being worth it.
The problem with dexcool is that it is wonderful coolant until it isn't. I don't want a coolant in my system that turns to death when it touches.... AIR. Seriously. Air?
It's ridiculously delicate stuff. When I hear stories like "300k and no problems," I know from experience that the only word to describe that is "lucky." Not having problems with Dexcool is an anomaly and extremely rare. I strongly urge you to not listen to the 2 dozen people who don't have problems, and DO listen to the multiple millions of people involved in dozens of class-action lawsuits for cars that had severe problems. Dexcool is one of the reasons that Saturn and Saab no longer exist. I worked for GM during those years, and it was a nightmare. Warranty claims quadrupled in a span of two years, and all of those additional claims were coolant related.
Backflush the whole thing. Run it for a while on just water to really get stuff out of the nooks and crannies. I strongly suggest pulling the block drains. My guess is that you'll not like what you find. There is a good chance that the block jackets are half-filled with sediment. Also, don't expect the backflushing of the heater core to be entirely successful. By the time you lose heat, it is usually too late to save the core. I turns into sandy orange jello that you can't really dissolve. If you flush it and don't have full heat on just water, don't refill with green until you replace the core.
The good news is that you can get rid of it with good flushing and a new heater core (if needed). It's also unlikely that it has caused any damage. It's not like it's causing engine explosions, it's just annoying stuff, like losing heat. Refill with 50/50 green and it will be fine. I will never understand why people would want a long-life coolant that isn't long-life and can cause multiple annoying and damaging problems.
My vote is flush with malice, replace with vengeance, and kill it with a blowtorch while videoing it so you can show its Dexcool friends what happens to coolant that sucks.
