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Thread: Brown Sludge

  1. #1
    Jr. Apprentice
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    Jan 2010
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    Baytown, Texas
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    Default Brown Sludge

    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. #2

    Default

    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
    David
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  3. #3

    Default

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

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  4. #4

    Default

    Quote Originally Posted by stchman View Post
    If you Chevy truck takes Dexcool and someone mixed the green antifreeze, the combination can cause a brown sludge.
    Yup. Mostly likely this. @spud is the radiator OE?
    Clint (TX) 2001 Silverado LS 4.8L auto 2wd ECSB [GARAGE]
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  5. #5
    Jr. Apprentice
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    Jan 2010
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    Baytown, Texas
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    Default

    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. #6

    Default

    Quote Originally Posted by spud View Post
    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.
    You should have a seperate transcooler then (but still check). Could be what @stchman and @McClintoc said.

  7. #7
    Legend

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    Default

    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. #8

    Default

    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.

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  9. #9

    Default

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

  10. #10
    Jr. Apprentice
    Join Date
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    Baytown, Texas
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    Default

    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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