Constant coolant loss

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by mstr33t, Apr 12, 2012.

  1. mstr33t

    mstr33t New Member

    I have an '04 Silverado with the 4.8 liter V8. I don't see any external leaks but my coolant keeps going low. I have to keep topping off my coolant or my engine will run too hot. Do any of you know what the issue could be? I have heard of cracked cylinder heads if they are from Castech. I can't find a whole lot when searching for Technical Service Bulletins.

  2. paracutin

    paracutin Rockstar 100 Posts

    If you can't find a leak I would guess you are burning it. Cracked head, bad head gasket, something.
    How many miles are on it? How much coolant are you using?
  3. osgprometheus

    osgprometheus Rockstar 100 Posts

    Have you looked at your motor oil to check for moisture in it? Any moisture in the passange floor board?
  4. Revredneck

    Revredneck Rockstar 100 Posts

    Have you done a pressure test on the cooling system? Does it drip on the driveway when you park it? Hopefully, it's just a weeping water pump or a seeping hose.
    Good Luck and God Bless
  5. mstr33t

    mstr33t New Member

    I have checked my oil several times and have not seen it turn milky. I had a radiator flush done on it and they said no leaks were detected. I am quite certain it is being burned or it is evaporating in the heads or something like that. My exhaust isn't smokey. I have not seen any liquids on my floorboard. My truck has around 97,925 miles. I have had to top it off with about half a gallon of coolant once a month. It gets low pretty quickly.
  6. paracutin

    paracutin Rockstar 100 Posts

    Try some coolant dye. If there is a leak anywhere you will see it. It's cheap and easy.
    You can also look at the plugs. If one or more is whiter than the others it is possible that cylinder is burning coolant. You can also give the exhaust a good sniff. A sweet smell would indicate coolant.
  7. mstr33t

    mstr33t New Member

    OK I'll give those things a shot. Hopefully it narrows the possibilities down. Thanks!
  8. billnorman

    billnorman Rockstar 100 Posts

    Are these motors susceptable to intake manifold coolant leaks?
  9. paracutin

    paracutin Rockstar 100 Posts

    Yes. Dexcool, as it gets old, has been known to degrade the rubber seals around the intake ports.
    It is supposed to be good for 100,000 miles but I wouldn't recommend running it that long.
  10. Jimmeh

    Jimmeh Epic Member 5+ Years 500 Posts

    Good info. I have had this same problem with no leaks to be found and no moisture in my oil either. Will be switching from Dexcool ASAP.

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