I finally got around to draining my coolant system to get ready to pull my radiator, intake, heads, and maybe the whole engine, and noticed the dreaded dexcool radiator sludge all over the inside of the radiator. (No wonder the stupid thing ran so hot.)

I've done some searches and I hate that there's 20 different supposed "solutions" on how to get rid of it. Anyone have a sure-fire / GM-recommended way to get rid of dexcool sludge?

-I'm replacing my water pump and radiator, but I'm more worried about the coolant passages inside the block than anything...



Adam

 

Wood Bleach as a Flush (Oxilic Acid) and Baking Soda as a neutralizer afterward. This use to be the ingredients of Prestones Two-Part flush some years ago after it was banned in 05'
The stuff works! Just be patient........and run ONLY Distilled water afterward.
Wood Bleach is available at Home Depot.

Jebby

 

Jebby: Any mix / dosage instructions for each?


Is this ok to use with aluminum heads?

(Many of the flush products say no...)


Adam

 

Sure you can use it with aluminum heads.....just make sure you neutralize it.....it will not damage anything in the time frame of usage we are talking about......the old Prestone Two-Part cans were like 8 ounces of each product.........
You need to drain out any coolant in the motor and refill before using the flush.

Jebby

 

So refill everything with water, a splash of green coolant, mix a bit more water with 8oz of the wood bleach and finish filling the radiator. Then what? Let the motor come up to temp and run for like 20 minutes? An Hour?

Then let it cool down and add the baking soda after thoroughly dissolving it in a bit more water and run it for another 10-15 minutes?

Drain completely. Flush out the residual homemade flush solution with a bit more water and then fill the cooling system as normal?


Adam

 

 

Distilled water is about a buck per gallon at any grocery store. You'll need 5 or 6 gallons to do the flush and then to refill with 50/50 coolant mix (depending on how much of the stuff you can get drained from your radiator & block).

 

For what it is worth:

ALL of the above information is 100% correct...including making sure you use ONLY distilled water when mixing it with your coolant that requires water. Some coolants such as EVANS does not use any water...which is why wrote that.

YES..I have dealt with enough engines with the DEX-COOL coolant in them that turns to literally a mud like sludge...that I wish that those people who use it...understand THAT IT does need to be serviced and changed out...regardless what GM states.

DUB

 

DUB...

I was under the impression that DEX-COOL was intended for 'all-aluminum' engines. I've always used regular ethylene-glycol in my cast iron engine and never had a problem.

Not sure what is best for combination (iron and aluminum) engines.

 

GM put the DEX-COOL in the C4 engines that were still cast iron blocks with aluminum heads.

Like most people...the coolant along with brake fluid are often times ignored. And the cast iron engines with the DEX-COOL in them would turn to this sludge over time....even though I think the 'hype' of it being a coolant that can last for 100K mile is a joke.

I am a fan of the ethylene glycol coolants along with the Evans coolant. I still use the DEX-COOL but only in those cars that have it such as the LS engines I work on. And so far...all of the LS engines I have drained the DEX-COOL out of the coolant was just fine and no signs of sludge.

The only time I see any sign of sludge on a cast iron engine that has the green coolant in it is due to the block drains were never removed. And when I get the coolant to come out...the last 5-10 seconds of draining the crap will come out.

I check the green coolant using my volt meter...often times it fails even though it passes on how well it can protect. I do not know how many people know about this.

DUB

 

Good info Dub.

And this is how DUB does it with a voltmeter.

https://www.google.com/search?q=how+...hrome&ie=UTF-8

 

Dex-Cool needs to be replaced every 5 years. No one does it though thus sludge.

 

The voltmeter is an excellent way to measure any electrolytic corrosion going on! It's what causes an aluminum filler neck to die first on an iron engine. Bi-metalic engines (alum/iron) are more susceptable to this than all-iron or all-aluminum motors.Copper/iron doesn't cause much of a problem but aluminum/iron does. I'm not sure about copper/aluminum but you don't see that much. It's the reason why aluminum radiators, intakes, overflow tanks and heater cores are more fragile on these iron engines. The distilled water mixed with the antifreeze is critical to slowing down or stopping the formation of dissolved ions that conduct the electricity. Tap water has ions in it and conducts electricity! It is also the use of a zinc sacrificial anode added to your radiator cap is a good idea and will protect your aluminum radiator. Not needed as badly with a copper rad. Some Fords used aluminum heater cores (Taurus) and had a electrolytic grounding problem, and would go thru heater cores in a year or two. I wouldn't worry so much about the distilled water on the flushing, because your adding so many ions anyway, but I would neutralize it very well (baking soda), and then flush it very well with tap water. I would use distilled water on the last flush to make sure all the tap water and ions are out.
Here's a detailed way to test the system: http://www.rondavisradiators.com/tech.htm
And if you still have a problem you can always run a ground wire to your expensive aluminum radiator!.