1. Radiator stop leak for heater box leak?

    I've been smelling hot coolant in the cabin when the heater runs on high temp, and I'm wondering if a radiator stop leak would work in the heater box. Anybody with a specific product recommendation?

  2. #2

    Re: Radiator stop leak for heater box leak?

    It might but it would be a LOT better to replace the heater core! I assume you double checked to make sure the hoses are tight, not leaking.

  3. #3
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    Re: Radiator stop leak for heater box leak?

    ^^Agree^^
    What year and model?
    Many


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  4. #4

    Re: Radiator stop leak for heater box leak?

    Can't believe I forgot to mention...I'm in a '96 XJ

    Not sure about these hoses though. What hoses should I check? Some under the dash somewhere? I would guess the hoses in the engine bay wouldn't make a difference in the cabin, although I could be wrong.

  5. #5
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    Radiator stop leak for heater box leak?

    Sometimes you will smell a boil over into the expansion tank.

    Is there fluid on the passenger side floor? If you leak you will eventually overheat due to letting air in. Do you smell any after shutting the engine off even after NOT using the heater?

    I Would not use stop leak even if temporary.


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    Last edited by JPNinPA; 04-08-2017 at 07:24 PM.
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  6. #6

    Re: Radiator stop leak for heater box leak?

    Only time I get the smell is when I'm running the heater on the highest temp, and then it's more noticeable the higher the fan is turned. Never seen any fluid but I haven't been looking for any either. I'm guessing the leak is fairly smallish. Exactly where should I be looking if it was just a small leak?

  7. #7
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    Re: Radiator stop leak for heater box leak?

    Well if only with the heater on and your model should have a vacuum valve for the heater its after the valve. The heater core or the tubing comming through the firewall part of the heater core.

    High speed is only the fan speed and just enough to get the fluid vaporized.

    Top your radiator off and keep the expansion tank filled properly.

    The only other thing I could think of is the core being blocked enough to restrict flow and blow past the radiator cap.


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    Re: Radiator stop leak for heater box leak?

    If you're not sure if you have a leak or not then do what JPNinPA mentioned and fill the radiator / expansion tank, then watch closely to see if the level drops.
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  9. #9

    Re: Radiator stop leak for heater box leak?

    Quote Originally Posted by JPNinPA View Post
    Well if only with the heater on and your model should have a vacuum valve for the heater its after the valve. The heater core or the tubing comming through the firewall part of the heater core.
    Yes thanks I'll get up under the dash and see what's going on. I think you're referring to that vacuum activated 4 way valve in the engine compartment involving the heater hose. Had to replace the Oreilly's version twice in 10 years as it keeps cracking and losing coolant. Would a leak there show up as a smell in the cabin somehow?


    Quote Originally Posted by JPNinPA View Post
    The only other thing I could think of is the core being blocked enough to restrict flow and blow past the radiator cap.
    Is 'core' the radiator itself? I think that radiator is only a couple years old so I'm guessing it should be ok. I've always kept fresh coolant in it. Or are you referring to if the heater core was blocked? Would that cause it to change how coolant flows at the rad cap?

  10. #10

    Re: Radiator stop leak for heater box leak?

    The heater core is basically a little radiator from which the heat is extracted. Normally placed behind the glove box. You'll see the heater hoses on the outside of the firewall. They connect to the heater core on the other side.

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    Re: Radiator stop leak for heater box leak?

    Quote Originally Posted by bradleyheathhays View Post
    Yes thanks I'll get up under the dash and see what's going on. I think you're referring to that vacuum activated 4 way valve in the engine compartment involving the heater hose. Had to replace the Oreilly's version twice in 10 years as it keeps cracking and losing coolant. Would a leak there show up as a smell in the cabin somehow?




    Is 'core' the radiator itself? I think that radiator is only a couple years old so I'm guessing it should be ok. I've always kept fresh coolant in it. Or are you referring to if the heater core was blocked? Would that cause it to change how coolant flows at the rad cap?
    Heater core blocked. In your jeep there is a vac valve that allows fluid to be pushed through the heater core. When not open the fluid bypasses. When open I believe all the fluid in that hose is passed through. If the heater core restricts or blocks flow less flow is going through the engine. That allows for more heating and more pressure.


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