73 K5 Heater Core Replacement Help

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by flynhi, Feb 15, 2003.

  1. flynhi

    flynhi Registered Member

    Jan 29, 2003
    Likes Received:
    Tracy, CA
    I did search both here and on the net, i have not found specific instructions on replacing the heater core in my 73 K5 with air ... i am guessing that it comes out from the engine compartment( What do I know Though ) this is my first experience with a K5 and all of you have been a great Help in the past. An email or a link with Pics would be great .... Other wise i am going to have to take it in to the shop where the quote was almost 300.00 when the core only costs like $40 so any help would be great ... I live in the Tracy Ca area and willing to drive to learn .. /forums/images/graemlins/confused.gif /forums/images/graemlins/1zhelp.gif
  2. BLZN4FN

    BLZN4FN 1/2 ton status

    Dec 19, 2000
    Likes Received:
    Englewood Colorado
    Go to the Technical section ther is a wright up on heater core
    Hope this helps,
  3. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

    Dec 28, 2001
    Likes Received:
    The Rustbelt
    It comes out from the inside. Pretty straighforward. You'll need to remove all the nuts off the studs from the engine compartment, the hoses, one is a bitch to get at btw the fender and firewall you'll find it. After all the nuts are removed, remove the glove box door and anything else in the way there, vaccumm lines to the vent's etc...then the whole box should come out with a little coaxing. If you have cables attached to the air vent adjusters on top, you can remove them, but there is usally enough slack to allow you to set the box on the floor and unbolt the core from it.

  4. the professor

    the professor 1/2 ton status

    Feb 6, 2003
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    Ohhh boy...
    Open the hood..
    CAREFULY cut take the heater hoses off...NEVER TWIST...if you are replacing the core it doesn't matter..but if not the core is EXTREMELY fragile...
    Look at the heater blower box..the black thing...around the edge you wil see 7/16 head bolts and studs with 7/16 nuts you can't see the one under the blower, between it and the fender liner...do by the Braile method...

    REMOVE ALL THE NUTS FROM ANY AND ALL STUDS..feel around..as I remember there are four...
    Open the right door...
    Remove the glove box
    Remove the ash tray and housing...
    Remove courtesy lights if any
    Remove the duct coming out over the tunnel
    Get a light..
    Remove the right kick panel recirculating door cover.(the bulge in the top of the panel)..
    Dissconnect the vaccum line to the actuating diaphram
    Pull on the heater box and see if it comes loose, or if it rocks like you missed a bolt..locate any remaining bolts...
    Once you get it started coming out, disconnect the cool/hot air door actuating cable from the top of the box..there is a spring clip holding the loop end of the cable on, it will proably break when you take it off..don't worry..it will work without it...
    Check the left end of the box throught the ashtray opening..there is a diaphram with a vacuum line..disconnect it..
    Work the box out from under the dash
    Watch for hose, vacume lines, and wires that you may have missed..
    I suggest you put plastic, or a pile of towels under the box on the floor, coolant will probably come out of the core
    When you get the box out, you will see how the core comes out...wash the box in soapy water..or you will smell antifreez for awhile..
    Reverse for installation

    I HATE this job, its not hard, just a pain..... /forums/images/graemlins/mad.gif

    Good luck..and DO NOT twist the NEW heater hoses when you put them on...lube them with WD40 and slip them on...Leave SLACK in the hoses,hook them to the fender-well NEVER string them tight..it will strain the core and it will crack...

    /forums/images/graemlins/cool.gif /forums/images/graemlins/truck.gif
  5. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

    Feb 17, 2000
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    The Search on here defaults to last 30 days and to just the forum you were in when you hit the search button. Best way to use it is to select "all forums" and "1 year" or "all" for the time. I checked and it pulled up plenty of posts about the heater core.
    Here is the tech write up I did a couple years ago. Should let you know what to expect. It was done on a 75 with A/C. Some folks have done the job without pulling the inner fender and usuing a couple univerals to get to the lower retaining nut to do the job. Expect about a day to do the job if your a novice. While this isn't a easy job I think it's well within most peoples ability if you have a good selection of sockets and extensions. Juts a lot of parts to come free and that's the time consuming part. If you have air tools it will save you a lot of time and get the inner fender out of the way in a few minutes.
    Welcome to CK5.

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