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Heater core leaking

Heating / Cooling / AC

  1. Ls1slow

    Ls1slow Member

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    Looking for some help to verify that is my heater core leaking before I take everything apart. But on passenger side it leaks a little bit of radiator fluid it use to be a intermittent problem but towards end of fall last year it was about every time I drove it. It’s doesn’t leak into the interior that I can feel it smell. It only drips along passenger side frame rall.
    I’ve checked the hoses going into the heater core and it’s not leaking there or in the Engine bay. But what else could be leaking fluid in this area besides the heater core. I’ll post a few pictures of where the fluid comes from and how much drips. Worried it’s going to get worse leak into interior or lose all radiator fluid driving.

    B5F03E11-6CB4-4E90-9E10-0DC03596E213.jpeg

    5846546E-79AB-43FD-B647-2F923B56DBA7.jpeg

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  2. moparlee

    moparlee Well-Known Member

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    More than likely it is the heater core. In the mean time if you want to drive the car just disconnect the heater hoses at the water pump and plug them off.
     
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  3. MerlinsMopars

    MerlinsMopars Well-Known Member

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    Could be an outer header or manifold bolt too or just some overflow coming out the tube but if its just leaking straight down, most likely heater core. Atleast if you block it off and the leak stops, then you'll know.
     
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  4. Ls1slow

    Ls1slow Member

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    Ok will since it’s on passenger side and opposite of overflow tube I know it’s not that. And you think out of a manifold bolt like a crack in the head. I haven’t seen any where in engine bay where it leaking even where the heater core tubes stick through the firewall.
     
  5. MerlinsMopars

    MerlinsMopars Well-Known Member

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    The outside manifold bolts go into the water jacket and can leak if you dont use sealer on them. Looks like it is leaking thru the firewall where its sectioned together and more than likely the core. You could also have a pin hole in a freeze plug and squirting there.
     
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  6. Ls1slow

    Ls1slow Member

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    Ok thanks I’ve ran it and looked and haven’t seen anything. I’m pretty sure it’s the core but since can’t physically see it leak from core just like second options before rip the old one out. Thanks for help
     
  7. 413

    413 Well-Known Member

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    More info needed. Do you have factory A/C?
    If so it could be the water valve in the fender well leaking
    If it is leaking inside the car you would know it quickly with a warm engine. That antifreeze steam smells bad and fogs/slimes the glass.
     
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  8. Ls1slow

    Ls1slow Member

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    It’s not a factory AC car and doesn’t have AC.
     
  9. Rich G.

    Rich G. Well-Known Member

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    Get a pressure tester and pump it up. If theres a leak it will show up
     
  10. Ls1slow

    Ls1slow Member

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    That’s a good idea I didn’t think of that but what’s a good way to pressure test it. I couldn’t use a a regular radiator pressure tester. Because of the thermostat will be closed.
     
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  11. Rich G.

    Rich G. Well-Known Member

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    Pressure test will go through the heater core also . Thermostat doesn’t matter.
     
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  12. moparleo

    moparleo Well-Known Member

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    That is what a bypass hose, "bypasses"
     
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  13. rklein71

    rklein71 Well-Known Member

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    I would disconnect the heater hoses and set up a pressure test for only the heater core as a starting point. You could also do a vacuum test on the core as well.
     
  14. Ls1slow

    Ls1slow Member

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    So did a static pressure test like recommended it started to leak on the inside where tubes come through firewall so enough evidence for me to deal with replacing the heater core thanks for help. Probably asking for help if b pulling heater core coming up
     
  15. rklein71

    rklein71 Well-Known Member

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    Good news, summer is coming, not much need for the heater core for a while...
     
  16. Rich G.

    Rich G. Well-Known Member

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    If you’re replacing the heater core you might want to get a heater box restoration kit from Detroit Muscle Tecnologies while you have it out and apart. After 50 years I’m sure all the foam seals turned to dust.
     
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  17. Ls1slow

    Ls1slow Member

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    I know I looked into it sure seals are bad as well car it is a super original car. And only had a basic restoration before I bought it and from what I see still has original date stamps on heater box. And a dump question but would bad seals case it to blow hot air when vents are open.
     
    Last edited: Mar 26, 2020 at 10:28 AM
  18. Rich G.

    Rich G. Well-Known Member

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    Very possible. While it’s apart you can check to see if the doors close properly
     
  19. rklein71

    rklein71 Well-Known Member

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    When I did my heater box, I bought some cheapo 1/4 inch black foam from Walmart. It was in a package for sealing a home air conditioner and cost me a 50 cents because it was on clearance. I used spray glue to recreate the flapper seals and such. Worked great. Rod

    IMG_3717.JPG
     
  20. timdp

    timdp Member

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    Whatever you do, don't buy a heater core from Summit. Zero quality control on those regarding fit. Have bought two of them and neither would fit into the heater box, even with mods. One was badly out of square and the other was 1/8" too big to fit. Still looking for a quality piece.