Heater core replacement 72 Chero

Discussion in 'General Ranchero Help' started by GRUMANIA, Sep 23, 2019.

  1. GRUMANIA

    GRUMANIA In Third Gear

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    Has anyone ever changed the heater core in a 72 Chero ? Mine is terribly leaking and every time I want to defrost the windows, steam fills the car.
    As I see, its not impossible to get to the heater core from the engnie bay, there are just the two water hoses , no inspection hatch.
    When I look at the heater box inside the car, there are no visible screws to get the box off.Does anyone know what to do ?
    Thanks
    Ilja
     
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  2. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    The top of the box in the engine compartment should be the lid. '72-'79 is all the same, and I did mine last year. Look for screws around the top's outside edge.
     
  3. andrewok1

    andrewok1 In Maximum Overdrive GOLD MEMBER SILVER MEMBER

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    Handy - the heater core in a 1972 -76 needs removed from under the dash ,inside passenger side ,you start with removing most of your coolant ,
    its a PITA - i had the diagram ,cant find it
     
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  4. aquartlow

    aquartlow In Maximum Overdrive

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    '77-'79 heater cores are a helluva lot easier to get at and change than the '72-'76 models
     
  5. Hillbilly

    Hillbilly In Maximum Overdrive

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    Adding this = On 72 thru 76 I remove the heater hoses from the core and flush out the antifreeze with a garden hose before attempting to remove the core. Plain ol' water will dry up if you spill any on the carpet unlike coolant that stays wet and rots the floor.
     
  6. andrewok1

    andrewok1 In Maximum Overdrive GOLD MEMBER SILVER MEMBER

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    i found this write up on this site
    Ok. In the interest of participating in the forum, here are the procedures as outlined in the 1973 Ford Car Shop Manual for removing the heater core. I'll provide my observations and lessons learned on this job.

    All told, the job could have taken much less time than it actually did. I started at 230 pm and ended at 915 that evening. The extreme length of time was due to two main factors: 1) A plenum screw from hell which was in a crappy position 2) New core had its retaining bracket in the wrong place.

    Here are the procedures per the manual:

    "The heater core can be removed from inside the vehicle by removing the plenum chamber rear case half.
    1. Drain the engine coolant and disconnect the heater hoses from the heater core.
    2. Remove the glove box.
    3. Remove the heater air outlet register from the plenum assembly.
    4. Remove the temperature control cable assembly mounting screw, and disconnect the end of the cable from the blend door crank arm.
    5. Remove the blue and red vacuum hoses from the high/low door vacuum motor; the yellow hose from the panel-defrost door motor, and the brown hose at the inline too connector to the temperature bypass door motor.
    6. Disconnect the wiring connector from the resistor.
    7. Remove ten screws from around the flange of the plenum case and remove the rear case half of the plenum.
    8. Remove the mounting nut from the heater core tube support bracket.
    9. To provide a positive seal between the front and rear case halves, apply body sealer around the case flanges before installation. Make sure that the core mounting gasket is installed properly during installation of the heater core."

    Lessons learned:

    1. A towel laid down on the floor under the plenum is essential to preventing staining and a mess. Do it. Trust me.
    2. Draining engine coolant is not necessary. Just make sure the engine is cold and coolant is not under any pressure. I didn't remove the lines until the last step to prevent making an early mess.
    3. Removing the glove box is self-explanatory.
    4. Dropping heater air outlet register is a snap. Putting it back in can be a little tricky, just mind the big tab on the rear and ensure it seats properly.
    5. Disconnecting the crank arm isn't necessary. I couldn't do it because the retaining spring was seized onto the crank arm. doesn't hurt operation, just can't disconnect it.
    6. Temp control cable mounting screw is easy to get to.
    7. Red and blue vacuum lines must come off. The rest don't and are not necessary unless you don't want to fool with them getting in the way when you reassemble. I had minimal problems with them interfering.
    8. Disconnecting the wiring connector from the resistor is self-explanatory.
    9. Remove the ten plenum screws. Nine of these are easy to get to. The tenth, which is next to the control cable mounting screw is not. I ran threw my list of popular swear words and began inventing new ones during the removal of this screw. This one took up most of my wasted time...both installation and removal. It's situated right next to a post which the dashboard mounts to. The post is unyielding and the room to work is small. I tried every combination of sockets, universals and extensions to get it out and finally did, but it took a long time. Removing the radiom might have helped, but I didn't want to risk breaking anything outside the heater core job itself. Have patience, it will come off.
    10. Remove the rear plenum case. Be ready to play around with it to get it out. The blending door may inhibit removal, just play with it.
    11. Removing heater core mounting nut is self-explanatory.
    12. Remove core and drain, be careful not to spill it (hence the towel).
    13. Install core. But before you do, check the position of the mounting bracket on the new core. Is it too far up (closer to outlet ends) than the old one? If so, desolder it and move it back...or cut it and discard. This cost me time as it took me a while to figure out why I couldn't get the plenum assembly back together. The distance the bracket was off is the exact distance the top of the plenum would not close. Also, I managed to break one of the outlet solder joints in the process of hacksawing the bracket off. This cost me more time as I didn't have a propane torch or solder to fix it. I resoldered both outlet pipe joints just to be safe.
    14. If you cut the bracket off, use the hoses to hold the new core in place.
    15. Practice putting the rear case half back on before you put the body filler on. I actually used some #2 non-hardening sealant (black). It's made for sealing flange halves so I figured it would work. Good thing I practiced putting the flange half on, otherwise I'd have had sealant everywhere.
    16. The blending door will interfere with reassembly, just play with it again. The rear pin of the door fits into a countersunk hole in the middle of the box. It's easy to guide it in with your hand.
    17. If this is the first time you are replacing the core, your weather stripping may be disintegrated. If you have any engine heat permeating the cockpit while driving, even with the heat off, then the stripping may be bad. Take the time now to prep and restripe the blending door and center air distribution box above the plenum case. I did.

    Reinstallation of components is opposite of removal.

    After all the asspain, I have to say the heater works about 75% better than before. I didn't have one of these cars in 1973, so I'd guess it is working at factory specs now. I also noticed the water temp is significantly cooler now. Probably due to no loss of pressure or fluid during operation.

    All in all, not a difficult job but it did have its annoyances. If I had to do it again, I'd not have wasted time trying to install that stupid screw.

    Questions? Hope this helps someone.

    Formerly 1973 Ranchero 500
     
  7. LSChero

    LSChero In Maximum Overdrive PLATINUM MEMBER

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    If you have AC cruck,its a royal PIA.Repair OE core if possible,The repop one I installed wasnt a good fit.Good time to refurbish doors,blower motor,seals.
    AC Interior.jpg
     
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  8. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Wow. I didn't know that. I should consider myself lucky I didn't have to do the core on my '74 Squire.
     
  9. FrenchFan

    FrenchFan In Overdrive SILVER MEMBER

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    I replaced mine about 2 years ago, 11 or 12 screws to remove the housing cover from the housing under the dash (passenger side), 1 screw that hold the heater core.
    Some screws are difficult to put back in place, i remember adding a small amount of grease on the tip of the screwdriver to hold the screws....
     
  10. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Ugh, I hate heater box designs like that.
     
  11. GRUMANIA

    GRUMANIA In Third Gear

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    Location:
    Germany
    Thanks a lot, I will have a look at it.I just wonder why I did not see screws. I expected visible screws around the plenum, or at least some kind of clamps that hold it together.Instead of that, all I saw were round spots that look like rusty pop rivets.
     

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