Coolant probs 2001 century

[Rebel Racing 3]

Ok we have a strange putty in the rad of this car.............The owner did not mix any anti freeze....The putty is like a rusty color and if left out in open air it turns to a powder and looks like rust any ideas guys.....Also he did not put stop leak in it

[BNaylor]

GM used sealant tabs to help with sealing of the intake gaskets. Sounds like a cooling system flush and new coolant may be in order.

[Blue Bowtie]

Absolutely. That sounds very typical of a cooling system which has been neglected. That is exactly why some people have the notion that DexCool is not a good coolant.

The solids you are finding are likely being precipitated out of the coolant mixture because the coolant has exceeded its useful life, or has been contaminated by air, additives, or diluted with water containing high dissolved mineral content. DexCool is rated for a service life of five years or 100,000 miles - Whichever comes FIRST, not last. Unfortunately, that is usually understood by owners to mean that they don't have to do anything for five years (or more). The coolant level needs to be maintained (checked on a 90-day basis), and the solution needs to be tested for concentration, pH, and dissolved solids on an annual basis. If the vehicle was serviced at a factory trained service center and they neglected to do that, shame on them. If the vehicle was serviced somewhere else, we can only presume that they just didn't know any better. And despite the best efforts of the manufacturers, people somehow seem to miss all that information in the Owner's Manual.

You are evidently now at the point of cleaning all that solid and sludge out of the system, then refilling with the proper mixture. Hesitation might only cause more problems, such as hot spots in the heads, clogging of the deck and head passages, clogging the radiator or heater core, and their potential consequences. Since the coolant mixture is acidic, a caustic cleaning agent will likely work best to soften any deposits and residue. Follow that with a vigorous flush and possibly a second cleaning, then a refill of the correct mixture. Monitor the coolant condition for signs of additional sediment and sludge, and be prepared to clean the system again.

Even though many will suggest that the problem is the DexCool itself, and advise that you switch to "regular" PEG antifreeze, it's perhaps a bit ironic that all this "bad" DexCool and the cloned/similar OAT coolants are now being used by nearly ALL manufacturers, including those who sell "good" cars like Honda, Toyota, Nissan, Daimler, and BMW.

[BNaylor]

Originally Posted by Blue Bowtie

DexCool is rated for a service life of five years or 100,000 miles - Whichever comes FIRST, not last.

FYI. The recommended service life mileage for Dexcool stated above was revised to 150K miles. Years as stated is still 5. Even the aftermarket extended life coolants like Prestone and Peak EL advertise 150K miles.

Circa 2001 and up GM used sealant tabs on the 3100 Vin "J" and 3400 Vin "E" V6 engines. Many times Dex-cool sludge is confused with the residue left by the GM sealant tabs that was used at the factory. Basically it will appear as sludge and when dried look powdery with the reddish tint. The sealant tabs have been given a nickname of "Ginseng Root" since it appears herbal in nature.

And there is nothing wrong with Dex-cool. In one of my GM cars I'm going on the sixth year with 68K miles and it looks as good as brand spanking new Dex-cool out of the bottle.

BTW - I run the electrolysis test annually with a DMM and it passes. GM specifies nothing over 0.3 volts.