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  1. #1

    Default Coolant smell questions??

    First before I get blasted about searches...I did. I just couldn't find what I was looking for. I have a 2004 Silverado Z71, 5.3 auto bla bla. The other night I was on my way home (after a good run down the highway) I started to smell coolant and assumed it was the heater core. I parked the truck at home, checked the passenger side for a wet floor. It was dry. I checked under the hood at the coolant bottle and it looked fine, at the full mark. I didnt notice any leaking around the hoses, water pump, t-stat, or intake. Did I miss somthing? Is it time to take it in to the dealership(I hate them by the way)?
    Last edited by bb55hrt; 11-02-2011 at 09:04 PM.
    2004 Silverado Z71, K&N cold air intake, mbrp catback w/dual tailpipes and 3" stainless tips

  2. #2


    I would double-check around your water pump, specifically at the bottom of it (you can't really see the bottom well because the A/C pump is in the way). There is a seal inside that will let coolant leak out of a pinhole drain at the bottom if the seal wears out. I just had to replace the water pump in my 2003 Avalanche at 110,000km - about 65,000 miles, and it seems fairly common for the 2003+ water pumps to fail at lower mileages than the older ones. My 2001 Silverado had 315,000km - almost 200,000 miles on it when I sold it and it was still on its original pump.

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  3. #3


    I might suggest hooking a cooling system pressure tester to it. Some parts stores (like Autozone) will have them as part of a tool lending service. Then you can pressure the sytem up while it's cold, wait a while, and see if there are any places where coolant is dripping.
    '98 K1500 Suburban LS 5.7 L 4L60E NV246 ARB
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  4. #4

    Join Date
    Jun 2006
    River Ridge Louisiana-4 miles W of New Orleans-didn't flood-water stopped 800 yards away.


    If you don't find the leak-just keep checking the coolant level-EVERYDAY!
    Eventually the leaking will increase you you will find a drip spot!
    I smelled coolant for years- find a number of leaks-repaired replaced until I finally sealed it up again- no smell
    Radiator leaked
    Water pump
    Intake gaskets
    Finally a heater hose triple connector- no smell now
    But mine has 217,000 miles- 98 Suburban
    Keep looking checking coolant levels
    1998 suburban-
    1/2 ton

    199500 miles

  5. #5


    I'm going with heater core. Even if the heater core is leaking profusely, it's probably going to drain out the AC evap drain to the outside. But here is what's probably happening....When you are running the truck steady and it's hot, the cooling system is at 15 psi, the coolant going into the heater core is about 200 degrees. Assuming there is a pinhole leak in the core, the coolant is spraying out from that hole into a zero pressure environment. Because the coolant is so hot, combined with the instant, drastic pressure change, the coolant is immediately vaporizing. It's the same principle as the orifice tube in your AC, which makes the whole system work. That vaporized coolant is what you smell. If the leak gets bad enough, enough coolant will be dispelled that it will start condensing on a cold surface like the windshield.

    When I finally got around to replacing my heater core, I had to clean the inside of the windshield every week or so, and add water/coolant. The leak was so small there was a tiny green dot on the core.
    When you hear hoofbeats, look for horses not zebras.

  6. #6


    Thanks for all the fast responses. pmf608, I checked the bottom of the water pump, used a small mirror, I didnt see a thing. Not even any residue.. mr shorty, I will have to look into the pressure tester. phoebeisis, I'll definetly keep an eye on the level i really dont want to blow this truck up. 2cor517, i agree with you I still think its a heater core. I'm no mechanic, but I have driven many junky vehicals, you learn alot when they break down. Your expaination sounds very plausable. I think you are right.
    Thanks again. i'm just going to keep an eye on it for a little while longer. when I get a chance I might just drop it at the stealership and let them at it.

  7. #7

    Join Date
    Jun 2006
    River Ridge Louisiana-4 miles W of New Orleans-didn't flood-water stopped 800 yards away.


    Yeah, if the odor is heavy inside the truck cab-core sounds right.
    On the bright side if the leak is amall there isn't any huge rush-just keep it filled.
    If the leak suddenly increases you can probably bypass it until you get a chance to repair /replace it-apparently it is a pain in the to replace it- hours of work in tight quarters

  8. #8


    I've also heard/read that it is a few hours worth of work to replace the heater core. My advice would be to replace it yourself if you are capable of it, otherwise it could easily cost over $1000 (with the $139 labor rate around here anyway)

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