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  1. #1
    Sr. Apprentice
    Join Date
    Jun 2010
    new england

    Angry help with unfindable coolant leak

    I can not find where leak is coming from its dripping onto to rock gaurd. got under there and its wet along a wire harness runs along front of oil pan ? pass side of that harness is tied to the trans cool lines to radiator which one is also got coolant covering it (the lower line to radiator ) but that cant be leak cause its trany fluid going through that right??. thats only place i can see any coolant on, front of engine dry, nothing on water pump or from weep hole under it, but im loseing coolant slowly have to put about a quart in every 3-4 weeks any ideas anyone?? its driving me nuts. also all the regular places (radiator/hoses/waterpump/thermostat ) all dry.

  2. #2


    Put some dye in the rad that reacts to black light, run it, then hit it with the blacklight to find where its coming from.

  3. #3
    Master Mechanic
    Dirty Dog's Avatar
    Join Date
    Mar 2012
    Regina Saskatchewan Canada
    Blog Entries


    Yeps 07Xcsb has it right,,, just give a good wash down first, then let it dry, run till normal operating temp and you shall win.....
    you can get the dye almost any auto supply shop....

  4. #4


    Just rent a pressure tester from autozone and pressurize your system. You might find the leak pretty quickly. My water pump had a slow leak that I could not find. I pressurized it and it pours out. It could just be a bad hose clamp.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors,
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  5. #5
    Sr. Apprentice
    Join Date
    Nov 2008
    Endicott, NY


    If you can get your hand behind the water pump pulley find out if it feels sticky in that area. I had a pump leak on one car that would only occur after the car sat for several hours. The dealer and I could not find the leak and I felt all around the water pump and noticed that it felt sticky behind the pulley. One day I had the car in the air working on it and went in the house to eat lunch. A half hour later I came out and there was a drop of coolant on the floor where there hadn't been any before. I looked up and the otherwise dry pulley was wet. The engine hadn't been run in a day and it took close to 24 hours for the leak to start.


  6. #6


    As long as you don't get it on your finish, you can mix a bucket of hot water and Tri Sodium Phosphate (get it in paint supply stores or paint section of hardware store) with some dish soap, and brush it on all areas wet with coolant or oil in suspected area. Let it dry after rinsing thoroughly. Run truck for a day and then examine area in question. This should narrow down the area. Might take a few days or a week of driving.

    I would find your drain plug and make darn sure the o ring is still intact in there. I had a similar confounding coolant leak, and it looked like it was not the drain plug but eventually I took the plug all the way out and sure enough, the o ring was bad.
    1994 Chevy K2500 Silverado, 454 (modified), original owner.
    And other vehicles and toys.

    "...If you can meet with triumph and disaster
    And treat those two imposters just the same;'ll be a Man, my son!" Rudyard Kipling

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