2006 Cobalt 2.2L -Gunk in overflow tank

Messages
233
Location
Pittsburgh,Pa.
I am seeing some crud, a tan color, in the top of the plastic overflow tank on my son's Cobalt. Has 34,000mi and has never had the coolant system serviced. Is this normal or is this the dreaded Dex Cool sludge-ing starting. The coolant in the reservoir is still to the full cold mark and red. Have never added any fluid. Anyone see this before?
 
Messages
23
Location
Houston, TX
You might want to have the coolant checked for combustion gases - the only time I've seen gunk in an overflow was oil from a head gasket starting to go. But I've only owned one dex-cool car and it never sludged, maybe I was just lucky.
 
Messages
528
Location
Kansas
Possilble, but could be just scale buildup. Dex-cool does better with aluminum head/block engines like the Ecotec. Even though, I always flush my GMs every 3 years or 30-40k. Have it flushed and have the cap pressure checked.
 
Messages
3,130
Location
Phila,PA
 Originally Posted By: Jason2007
Sounds like it could be Dex-sludge. Id flush it out and replace with some Peak Global Lifetime.
+1 I would even be tempted to remove the little plastic tank and clean that out by hand. Yes it will not help whats in the radiator, lines ,and block. But I would still want to remove as mush as I can. I'd change out the fluid with just water. Run that for a day as a mild flush. Then replace again with Peak.
 

pbm

Messages
8,748
Location
New York
GM used to use 'sealing pellets' from the factory which appeared like Dex-sludge in the overflow tank.. I don't know when they stopped but I would be very surprised if you have Dex-sludge in an ecco-tec at such low mileage.
 
Messages
2,097
Location
kansastan
Dexcool only fails due to a lack of maintenance, I'm told... so this is YOUR fault. See, GM clearly states that Dexcool is good for 5 years/100,000 miles, so OBVIOUSLY you did something wrong.
 

scudpilot

Thread starter
Messages
233
Location
Pittsburgh,Pa.
Thanks All. Although the problem is not severe,YET, I cleaned out the plastic tank and it was kind of slimy. I also made an appt. at a local radiator shop to completely flush and refill the cooling system. They say they use a flush machine, probably like the GM dealers do. Gonna see if they can completely change the fluid to Peak Global also.
 
Messages
18,261
Location
Michigan
 Originally Posted By: scudpilot
Thanks All. Although the problem is not severe,YET, I cleaned out the plastic tank and it was kind of slimy. I also made an appt. at a local radiator shop to completely flush and refill the cooling system. They say they use a flush machine, probably like the GM dealers do. Gonna see if they can completely change the fluid to Peak Global also.
Mine looks fine...I still plan to flush it next year anyways...
 
Messages
520
Location
FL
 Originally Posted By: pbm
GM used to use 'sealing pellets' from the factory which appeared like Dex-sludge in the overflow tank.. I don't know when they stopped but I would be very surprised if you have Dex-sludge in an ecco-tec at such low mileage.
They still do. That is likely what the residue is in this case.
 
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