Brown Sludge

Discussion in 'Chevy Truck Talk & GM News' started by spud, Jul 19, 2013.

  1. spud

    spud New Member

    I am getting a brown colored sludge in my radiator reservoir. Does anyone know what this is? The engine has 250,000 miles on it and I had the radiator flushed about 2 yeras ago.
  2. dsfloyd

    dsfloyd Epic Member 5+ Years ROTM Winner 1000 Posts

    Is it foamy. I have seen it turn brown and foamy if tranny fluid gets in there, usually from one of the tranny cooler lines if it goes through the radiator
  3. stchman

    stchman Active Member 2 Years 1000 Posts

    If you Chevy truck takes Dexcool and someone mixed the green antifreeze, the combination can cause a brown sludge.
  4. McClintoc

    McClintoc ɹoʇɐɹǝpoɯ Staff Member 3 Years 1000 Posts

    Yup. Mostly likely this. [MENTION=32531]spud[/MENTION] is the radiator OE?
  5. spud

    spud New Member

    Yes, the radiator is OE

    - - - Updated - - -

    Yes it is a foamy. I will check the tranny cooler lines. The truck is a 2500 HD with a 6 liter in it.
  6. dsfloyd

    dsfloyd Epic Member 5+ Years ROTM Winner 1000 Posts

    You should have a seperate transcooler then (but still check). Could be what [MENTION=57614]stchman[/MENTION] and [MENTION=56140]McClintoc[/MENTION] said.
  7. j cat

    j cat Epic Member 5+ Years 1000 Posts

    dexcool must be used with distilled water. also only GM approved dexcool is dexcool ! compatible is not dexcool GM approved. now if this proper coolant was used with distilled water then you could have oil/tranny fluid entering the radiator. I would expect issues with the transmission and the fluid in the transmission if this is going on.

    in areas of warm not so often freezing temps the coolant systems do not have the proper dexcool added. with a lower percentage of dexcool the brown is rust. living in a warm area freezing protection is not #1 corrosion control is what will get you when the dexcool % is too low. these engines take 4.25 gallons of total coolant. that means 2 gallons of dexcool if the system was flushed , minimum .

    I use a 66% dexcool mix. replacing every 3-4 years.
  8. ChevyFan

    ChevyFan The Sheriff Staff Member 5+ Years 1000 Posts

    Wow, 250k and you've got a brown sludge problems. How long have you owned this truck? I do agree that mixing dexcool and other anti-freezed will cause some color issues. There is also some orange anti-freeze that I've seen people mix and cause some color issues.
  9. McClintoc

    McClintoc ɹoʇɐɹǝpoɯ Staff Member 3 Years 1000 Posts

    Internal corrosion of the radiator should be a concern here. May need to replace it.
  10. spud

    spud New Member

    I bought this truck new in 2002. I am the only owner. The auto repair shop said they think it is a head gasket. I have no water in the oil or transmission. They said it could be a "tiny" leak. They suggest flushing the radiator with detergent to get all the "oil" out and then watch it

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