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  1. #1
    Sr. Mechanic larryleeUSN's Avatar
    Join Date
    Jun 2009
    Now stationed in Mayport,Florida

    Default Dirty water in exhuast.

    Im sorry if theres already a post with this questioned. i searched it and couldnt find it. Im having an Issue. i just bought a truck. i dont know how often it was used before i go it. it was owned by an older guy who kept great care of his truck. its a 2000 GMC Sierra ext cab Z-71. its got the 5.3 in it. when i bought the truck i found an exhuast leak right where the pipes from the manifold come together at the Y pipe. theres a coupling there that has a leak. there was Black water comming from it. i wiped it and smelt it and it was just water. couldnt smell any kind of oil. the oil was just changed about 1.500 miles ago and was still in great condition. couldnt find a problem anywhere. any kinds of leaks. there was a lil oil by the drain plug where they drained it and a light film on the filter also. other than that nothing. doesn anyone have a clue of where this " BLACK WATER" could be from? i cheacked after i drove it an hour on the highway to take it home and nothing and a few days later and nothing again. Any help is greatly appreciated.
    Lawrence Lee,United States Navy, Engineering.
    2008 Silverado CC. Z71 4x4. leveling kit on with exhaust hopefully putting on soon

  2. #2
    murdog94's Avatar
    Join Date
    Feb 2008
    Cloquet, Minnesota, United States
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    Moisture and carbon mixing in the Exhaust.. Completely normal.


    1997 Chevy S-10 Blazer 4X4 with 330K miles and counting (Hunting rig).

    2009 Saturn Aura XE (wifes car)

    2011 F-150 Crew 4X4

    "Hold it to the floor till you see God.... Then Brake!!!!"

  3. #3


    Quote Originally Posted by murdog94 View Post
    Moisture and carbon mixing in the Exhaust.. Completely normal.
    x2. That is just water mixed with carbon. When you burn a carbon-based fuel such as gasoline, carbon and water vapor are produced, and all you are seeing there is that vapor being condensed. I find on my truck that a lot of that water vapor condenses into liquid when the engine is cold, but once it warms up it is mainly vapor, which is why you wouldn't notice it after driving it. All vehicles have some water production, but I think some more than others, such as these trucks. On mine, there is a small pinhole in the bottom rear of the muffler to drain all of the water that accumulates below the outlet of the muffler.

    2008 FORD F350. My new all-around truck.
    2001 Silverado Reg. Cab Not-So-Base -- SOLD
    2003 Avalanche Z71. No Cladding. Check out my Mod thread. - Crashed. Will be rebuilt soon.
    1974 Triumph Spitfire 1500 - Work in Progress
    2003 Sierra 3500 Duramax. The Newer, Better Work Truck -- FOR SALE

  4. #4
    Sr. Mechanic larryleeUSN's Avatar
    Join Date
    Jun 2009
    Now stationed in Mayport,Florida


    Thanks guys. i appreciate it. i wasnt to worried just wondering.

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