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Thread: antifreeze leak

  1. #1

    Default antifreeze leak

    I have an antifreeze leak in my 1999 chevy silverado. I have looked underneath for a trail and under the hood for one. I checked the oil to see if there was any kind of milky look to it or if any water came out with it and no luck. it has been about a year since it started and just recently has it started to get worse but i still cant find any clues to where it is leaking. Someone suggested a sealant you put in your system and others say that it will just clog pumps and cause more problems. any ideas?

  2. #2


    could be your water pump going out...before they go out they start leaking and it would just burn off on the engine and you wouldn't see a leak when you let the truck sit
    2004 chevy silverado "northwest edition" lifted on 35's

    1990 cherokee lifted on 32's

  3. #3
    Master Mechanic CarpenterGuy's Avatar
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    Jul 2008
    Leeds, Alabama


    I agree with the water pump. If you havent had it replaced within like 60,000 miles i beleive it is, then you'll need to get it replaced. My grandpa (who didn't take care of his van) had a wobbly, old water pump that stopped working one day and it basicly melted the engine. His antifreeze leaked too.
    2006 Silverado Z71 - 97,000 - totaled, RIP
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  4. #4
    Legend unplugged's Avatar
    Join Date
    Sep 2006
    High Deserts of SoCal

    Default How to pinpoint a coolant leak

    You need to isolate the location of the leak. Front, back or top of the engine. For the front of the engine, the water pump is the likely source. Intake or heater hose is common at the rear of the engine.

    Buy or borrow a cooling system pressure tester. With this you can pressurize the system and pinpoint the leak. About $70 from several online sources.

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  5. #5


    depends does it have the 5.7 or the 5.3
    with the 5.7 i would say its 50/50 intake or water pump
    5.3 i would bet on water pump

    2003 Z71 Silverado LS
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