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  1. #1

    Default Crap! heater leaking bad

    So I have to replace my heater core it is an a/c car. Any tips or shortcuts?

    so far every part I didnít replace on rebuild has failed or is failing
    it will get a brand new booster, heater core and transmission as they are the only remaining parts, and they are coming out
    Last edited by toddf; 09-02-2019 at 09:27 PM.

  2. #2


    Heater core replacement on AC cars is an all day job. The dash has to be either removed or at least lowered out of the way to get to the heater box. At that point its a snap. Go ahead and do the evap core too as its in the same spot. Of course vac out the ac system first. Then the dash gets reinstalled. Doable but takes a few hours. I replaced my heater core over a few days while off work. Took my time. Good luck.

  3. #3
    FEP Senior Member liv2roc's Avatar
    Join Date
    Jul 2009
    Cherryville n.c.


    I've done mine 3 time since I owned it over the last 20 something years the last time I did it in less than 2 hrs.

  4. #4


    If you are willing to cut up the box enough to swap the cores it makes the job 10x easier than if you fight with it.

    How necessary this is varies. Its impossible to get the heater core out without dropping the box on my son's 86 ragtop if it wasn't for that trick. On mine you can as my box sits a good 3/4" lower on the firewall. You'll do a small amount of damage to it in doing so. I trimmed my box and put the new heater core in place and sealed it back up.

    On my son's we cut the box, swapped cores, and used a good quality sealant and some ABS to repair the box once done.

  5. #5


    If your AC is not charged, you can disconnect the AC line by the firewall and that will give you better core box access once you get there.

  6. #6
    FEP Supporter webestang's Avatar
    Join Date
    May 2009
    St. Louis, MO.


    I've done mine twice on the 85. Takes me 3 hrs. I even drop the steering column.

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  7. #7

  8. #8


    I cut the front/top off the heater core area. Then seal it up with silicone when finished.
    No need to lose your A/C this way and only 2 corner bolts to remove on the box.

    Lots of FREE F/Z info on my site.

  9. #9


    If you have the luxury of taking your time while doing this job take a good look at replacing the seals in the box and giving everything a good cleaning while apart. Go slow, take your time. I'm a fan of not getting frustrated when doing tedious work by taking breaks away for a few minutes. My preference is to not cut anything that isn't absolutely necessary to. You will end up with a better end result.

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