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flat radiator hose

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by fireinthehole, Nov 14, 2003.

    When my truck is cold, the upper radiator hose is flat, but its fine when its warmed up. Its like there is vacuum in the lines somewhere. I pulled off the radiator cap to see if it would return to normal and it does a little. Everything is new, hoses, coolant, thermostat, etc...
    Anyone notice if theres does the same thing? I have never noticed this with any of my other trucks.
     
  1. Muddytazz

    Muddytazz 1 ton status

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    [ QUOTE ]
    the upper radiator hose is flat

    [/ QUOTE ]

    /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif Never seen that before, never heard of it for that matter. Sure seems like somethings wrong.
     
  2. HarryH3

    HarryH3 1 ton status Author

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    The radiator cap is probably shot. It is supposed to draw coolant from the overflow bottle as the engine cools.
     
  3. justhorsinaround

    justhorsinaround 3/4 ton status

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    I'm with Harry. If your radiator cap doesn't allow the overflow system to work i.e. draw coolant back in then a vacuum is created. Good luck to ya.

    Allan
     
  4. thats sucks, because its a new cap. I will replace it and see if that works.
     
  5. supersize75

    supersize75 1/2 ton status

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    Marv Spingers 454 powered buggy does that when he rev's it. Seems odd to me too /forums/images/graemlins/thinking.gif

    Sounds like a vaccume thing for shure though..just like sucking air fom a bottle /forums/images/graemlins/tongue.gif
     
  6. Smitty

    Smitty 1/2 ton status

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    I guess I could see it happening with the engine running if he has a high flow water pump on it. If you look at the thermostat as a restriction in the system there would be low pressure between the inlet on the water pump and the thermostat. As far as it happening to the hose when it's cold and the engine off, I'd have to agree with the rad cap.

    Smitty
     
  7. You were right about the cap. I replaced it and no more flat hose. It strange though, the one I replaced was new, but one of those lever types and I replaced it with a non-lever type and all is well. Thanks for the tip.
     
  8. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Are you sure it's a Gen-U-Wine Radiator hose?

    I know that at least ONE of the two radiator hoses has a metal spring coiled inside it to prevent it from collapsing (but I thought it was the LOWER one)...

    Just a wild guess from a guy who knows just enough to be dangerous on this topic...... /forums/images/graemlins/thumb.gif
     
  9. HarryH3

    HarryH3 1 ton status Author

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    Cool! /forums/images/graemlins/cool.gif

    Greg, the lower hose has a coil of wire inside, to keep the water pump from pulling it flat and restricting flow. The lower hose is on the suction side of the water pump. /forums/images/graemlins/thumb.gif

    There's a one-way valve on a modern radiator cap that opens under vacuum to pull coolant back from the overflow bottle. As the engine cools, a vacuum is formed in the cooling system. If the valve on the cap is stuck closed, then the upper hose can get sucked flat. /forums/images/graemlins/shocked.gif
     
  10. You know I noticed that when I took off the old hoses. I bought new Gates hoses, upper and lower, and didnt notice springs inside. Its working right now though. The overflow tank was way full before the new cap and now it down to the "full cold" mark as the rest of the coolant was pulled into the radiator.
     
  11. TrcksR4ME

    TrcksR4ME 1/2 ton status

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    I don't think they all come with the spring deal inside them anymore. Mine didn't, but I reused the old one /forums/images/graemlins/grin.gif
     

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