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Dex-Cool Replacement

8.5K views 28 replies 20 participants last post by  Seann  
#1 ·
I have a 2006 Dura-max with 56,000 mi how do you Flush the old coolant out, seems like a PIA does any one have any tips that has done it in this year of truck, How many Gals of coolant does it take.

Thanks Brad
 
#2 ·
I'd like to know too. How much, what brand and does water wetter work?
 
#3 ·
Unfortunately, I believe that 06 is the first year that they took the petcock (drain) out of the radiator. For the OP with that low of mileage- I would be inclined to just pull the bottom hose, reinstall when done draining, and refill with 50/50 mix of Dexcool and water. You can get Dex from almost any where- parts stores, walmart, etc. I'm thinking most of the time (at least from Wmart) it comes in a gray jug? Just make sure to get the straight and mix it yourself- why pay $XX for them adding water to it for you???? Anyway, refill it making sure to crack the bleeder at the top of the thermostat housing. When most of the air is out when filling it up, tighten (not OVERLY though) it back up, over fill your coolant a little bit more than what it should be, and then replace the cap. Take it out and drive it, check for any leaks, and monitor your coolant level for about a week (I usually just carry a jug of mixed with me for that week). If you need some, just add it (making sure system is NOT HOT when you crack the cap). If it had more miles, etc. on it, then I would be concerned about flushing- but with that few of miles on it, as long as it's not "nasty"- I would just do a drain and fill!
 
#4 ·
I would agree with drain and refill.
I do buy premixed. Because you want distilled water if you mix it. Just takes some of the hassel out of it. The minerals in water will cause the radiator and heater core to plug up quicker, and can also cause corrosion.
 
#5 ·
Is the 50/50 premixed with distilled water That you get at the store ?
 
#6 ·
I get straight coolant and distilled water is 89 cents at the market. I pull the lower hose , just put a kiddie pool under the truck and bail it out when your done. Think it takes 4 gals to drain/ refill ?
 
#7 ·
What I read on a post a while back:

Sorry, I guess I didn't read you post close enough and answer all your questions.
You should get 8-10 quarts or more when you drain the rad.
When you refill the system make sure you bleed the air out when you first start the engine after the thermostat opens bleed it again a few times just to make sure you have all the air out of the system. Make sure the coolant tank is at the proper level after the stat has opened and the system run a while and has had a chance to stabilize.
There is a bleeder on the thermostat housing. I included a pic to show you where it is. The bleeder is #58 in the pic.
 

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#9 ·
i'm going to tackle this too. i guess i'll pull off the lower hose but i really would like to " flush" some clean water threw before i fill it.

I have an '06 as well. i have well water that we don't drink and i certainly will not put into my truck! i'll buy gallons of distilled water i guess.

but i want all my coolant out, out of the heater core, out of every place it might be hiding. i'm not exactly sure how i'm going to get that done.

in the past with other vehicles i have taken off the upper hose and put the garden hose in the rad and ran the engine till clean. but i'm not using the garden hose this time. can i take off the upper hose and just pour in gallons of distilled into the resiviour and let the engine push it out the upper hose?

or what is the best method? i'll search on here, it's prolly in DIY section.
 
#10 ·
^^^^^ Drain, reinstall hose, fill with water, run truck to get warm (for thermostat to open), repeat until water drains clear. Just make sure when you go to fill it back up, you compensate for the water that is left in the block by putting straight coolant in for the first bit. I personally blow some low compressed air in the coolant tank with the lower hose still off and that helps get more out of it.
 
#11 ·
Using the garden hose I think works the best. Flushes the entires system and cleans out the heater core as well.Personally I am not a big fan of dexcool,I wouls rather use green coolant since it is far cheaper.
 
#14 ·
Difference is less than $1 anywhere around here :confused: Water from a hose has a lot of minerals in it that cause corrosion supposedly.
Any reason not to use green coolant after a flush? I have seen too many issues with Dexcool corroding fittings.
If all the dex isn't flushed it has been said it gels with the green. Can you be sure it's all out = no. Dex corrodes when it's been in too long that's all.
 
#15 ·
Before anybody thinks they really need to changeout,they should get a coolant analysis from a reputable lab like Cat,Schaeffer, or Blackstone.I thought for sure that at the very least I would have to add an inhibitor to my 2002 C7500 with a Cat 3126E.Never been changed[bought new] from the factory {Dexcool], only 39K miles--Cat said don't do anything to it,all normal,check back with us in a couple years.So now I'm going to do the same with my LBZ.
 
#16 ·
Unless its discolored or your at 100K I wouldn't change it. I just got 11 gal of distilled water and dropped the lower hoes. Filled it up took 3.5 gal. after a week dropped it again and again. Then drop it one last time and fill it with Dex concentrate.
 
#17 ·
After doing a lot of research, I decided to add a coolant bypass filter to my Dmax. Can be easily done for less than $100 and very important. I was not suprised, but disappointed, to learn how much crap floats around in there.

The Dexcool itself seems to be able to last a decent time, if you can keep it clean and keep the air out of it. Very important to have a functioning degas bottle and cap.
 
#20 ·
After doing a lot of research, I decided to add a coolant bypass filter to my Dmax. Can be easily done for less than $100 and very important. I was not suprised, but disappointed, to learn how much crap floats around in there.
All said and done I had I think ~$61~ in mine. And that's after I had to build and expensive brass "tee" when I couldn't source the poly-glass one in time.
 
#18 ·
I believe the manual says the coolant needs to be changed every 5 years/100K miles (whatever comes first). My 2007 Silverado Classic is 5 years old now based on the manufacturer date. I plan on changing it soon. I'm not sure exactly how much coolant to buy.
 
#19 ·
24 Quarts or 6 Gallons - from the 05 Owner's Manual

LMM/LBZ Cooling System, Initial Fill..........25.0 quarts
LLY Cooling System, Initial Fill..................24.0 quarts
LB7 Cooling System, AT Initial Fill.............20.0 quarts

 
#21 ·
That's cheaper than I thought it could be done.

I bought mine from nasautomotive for $92 shipped to my door.

I tried to build it myself and even using fleetfilter, I still was around $85, and that base is not as good as the aluminum one I got in my kit.
 
#22 ·
I'm gonna do a couple drain/refills on my truck.

Coolant still looks good, but I think it's just good for the system to keep that coolant fresh and remove any garbage.

Question is: That lower radiator hose clip attachment, is that a ***** to get off and will R&R'ing that thing a few times tend to make it "leaky" ???

Any advice is appreciated...
 
#26 ·
In our county, on the 1st Saturday of the month, we have a County Household Haz Waste 'roundup' where they accept all kinds of household haz waste, which would include most everything you have in your truck that might be drained out. Might check with your county or state to see if they have something similar.

It's always better to dispose of auto chems properly, if at all possible.
 
#25 ·
#27 ·
Mine only started leaking when it was left off for a week while we did head gaskets. Now it only seeps. There was a post on Duramax Diesels that has a cross reference # for the o-ring, apparently GM wants quite a few dollars for one.
 
#28 · (Edited)
Here's how I did it:

Bought a case of Amsoil Propylene Glycol Antifreeze and Engine Coolant.

Took case of coolant and one new Baldwin coolant bypass filter cartridge to my local radiator shop. They triple flushed the system, added the Amsoil coolant and changed the filter. Only used three of four gallons for the change, so I diluted the remaining gallon for make up - use a quart a year when I change the coolant filter.

Wrote a $150 check for the work, have a warranty in case anything went wrong. They disposed of the Dexcool so I didn't have to worry about it.

Dexcool and any ethylene glycol-based products are toxic and poisonous, here in California they are considered toxic waste, pouring them out on the ground could result in a major fine and Haz-Mat response. Propylene glycol is non-toxic and biodegradable where most areas don't require special disposal. It won't kill your pets if they walk through it and then lick their feet clean either, or cause liver damage if you get an accidental dose.

Amsoil has test strips to check the fluid, or you can send in a sample for analysis every few of years. The stuff is supposed to last seven years or 250,000 miles in light trucks, so one fill should do it for most of us. I'm coming up on three years so I'll send in a sample, I'd test more often if I was towing. I have had to replace numerous radiators on older trucks due to coolant breakdown where it polymerizes and plugs the tubes. Now I test and flush and refill when in doubt, because radiators plug slowly and always seem to know when you are somewhere like outside Kingman Arizona to completely fail.
 
#29 ·
The book I have says to pull the block heater to drain the coolant...
dont forget to flush the heater core.. pull both lines to it and reverse flush it.. you wont believe the crap that comes out.