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Antifreeze leak - 2003 Suburban 4x4 v8 5,3 ls 125000 miles

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by wdc1, Jan 29, 2014.

  1. wdc1

    wdc1 New Member

    Leaks on right side and can't figure from where. Its like trying to find where a roof leak is due to channeling.

    Oil clean, antifreeze clean, weep hole dry on water pump. Add about a quart every 2 weeks. No issues with vehicle otherwise.
  2. Scott_Anderson

    Scott_Anderson Member 2 Years 100 Posts

    Well I know that on my old 2000 5.7L I had an issue with the DexCool not playing nice with the intake manifold gasket material. I had a dealer replace the gaskets 1 time while still under the CPO warranty.
    The 2nd time that it started leaking again I had an independent shop replace them and use regular antifreeze, after that I had no more issues. I looked at the old gaskets that were removed and the rubber material in them were all swelled up and looked like crap.
    When it started leaking it was dripping from the right side at the back of the head.
    This was a big issue back in the day as I read about a recall for the 3.8L V-6 engines for this problem, but only the 6's. The V-8's were also susceptible but nothing was done as far as recall.
  3. okiemudslinger

    okiemudslinger New Member

    In my 01 Yukon XL I have a leak in the rear heater core has been leaking for 5 years it only need antifreeze added during the winter so I just add so any other month or so. but it could be you front heater core and it is coming out your condensate drain from your HVAC box.
  4. RayVoy

    RayVoy Active Member 2 Years 1000 Posts

    You say, it is leaking on the right side, have you notice wet areas?
  5. wdc1

    wdc1 New Member

    Its hard to determine wet area due to snow, wind, water and driving since when it leaks at 30 - 70mph drops spread. I will look at the heater core. I need to flush area with water when above freezing run it in the backyard for a while and see where it drips.
  6. wdc1

    wdc1 New Member

    This was a pain in the but to find. Cleaned engine with warm water first and let dry. For better clarity, I had to remove the 4 x4 splash shield then some brackets that hold some wiring and run the car at idle so the drops would come down by gravity and not capillary action due to driving and spraying all over the place.


    It appears to be a seal on the water pump. I will further confirm by idling it for a long time and then place a rag under it. Thanks
  7. Jamm3r

    Jamm3r Member 1 Year 100 Posts

    My cooling system pressure tester cost me $70 and has paid for itself many times over when chasing these sorts of problems.

    The best mechanics pressure test at every oil change interval to find leaks before they're serious
  8. wdc1

    wdc1 New Member

    Thanks bud. Which one did you buy since the suburbans, oe at least mine, do not have a radiator cap but a reservoir cap and the rented ones do not fit. Thanks.
  9. Jamm3r

    Jamm3r Member 1 Year 100 Posts

    I have a conversion cap made for the purpose. Threads on the bottom, bayonet on the top. Rock auto has them, just look up your vehicle and then look for cooling system tester adapter.

    The tester itself I've had for ages. I think I got it at Napa. They haven't changed much.
  10. wdc1

    wdc1 New Member

    Found out it was the water pump. Replaced pump, thermo, and radiator cap. Thanks for all your help.

    By the way as a tip for anyone who has to replace the pump it is not hard to do even for a nurdy scientist who loves to work on cars. The pump leaked from a seal but is still good but replaced anyways since at 125000 miles.

    Also that tester I found at Oreillys as a rental.

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