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Thread: 04 coolant leak

  1. #1

    Default 04 coolant leak

    hey guys
    I've got a 2004 5.3l v8 1500 and heres my problem. last week I had a puddle of coolant under my truck. My surge tank was bone dry but the only leak I could actually see was one of my trans cooler lines was wet with tranny fluid. I needed my truck for something so I just took water and put into my surge tank to keep my truck from overheating. since then my coolant level hasn't moved (no leaks other than the wet trans line). I feel like I'm missing something here. I was going to change my trans and coolant fluids soon, but I'd rather know what I'm getting into as far as the leak. Anybody got any suggestions or opinions as to whats causing my problem?

  2. #2
    murdog94's Avatar
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    I would take a look at the water pump, and all of the hoses. To start with.


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  3. #3


    If you have a small mirror look under the water pump for any weeping of coolant.

  4. #4


    I had the same problem with my exact same truck as yours, my local mechanic told me to pour some stop-leak in there to patch a potential hole up in the lines and over a year now and no problems since. Not sure if your problem is more severe than that but just a little tidbit on what worked for me
    Semper Fi

  5. #5


    I wouldn't use stop-leak except for a emergency, and then I would flush it out. It can do more harm than good. If it plugs holes, than it can plug radiators.

  6. #6


    You should rent a "Coolant System Pressure Tester" from Autozone.. (I don't know about your stores, but mine charges me a $250 deposit, and I get it all back once I return it so it ends up being free). (Most auto parts stores have it, just make sure it has the right connector to screw on to your coolant recovery tank. A lot of places have that connector in a separate kit, so make sure to ask for it!)
    That will allow you to bring the system up to full pressure (which is when 75% of leaks happen), and will cause the leak to occur and you can find out exactly where it's leaking from.

    I had a leak on my 5.3.. came down the front of the block ran along the side of the oil pan, and dripped down from there. Put the pressure tester on it, brought it up to pressure (look at what it says on the recovery tank cap, I can't remember off the top of my head but I want to say 14psi?) and found it leaking from the water pump area.. Turned out to be one of the water pump gaskets.. $5 fix and it was really easy to do myself..
    Last edited by JRD761; 03-28-2011 at 01:12 PM.
    2012 Silverado 1500
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  7. #7


    Just an update. I figured out the problem a while ago (I hope), but I haven't been on here in a while.
    It was the cap on my surge tank. Rented the pressure tester and my system held 15psi with no problems. Since then no leaks.

  8. #8


    Cool, glad it wasn't anything bad.

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