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I have a heater core leaking in my 1978 F100 and I have no clue how to get at the culprit. Under the hood I can see where the blower motor bolts on and where the heater hoses connect but not much else.
Under the dash I can see the big box and where all the wires and stuff, but no screws or bolts or anything.
If you have no AC there are 3 bolts under the hood to remove that will let you drop the whole plenum box, 2 hoses to disconnect, 2electrical connections, and 2 cables to undo under the dash. Theres a thread on here that was started in the last 2-3 days that shows a schematic of everything. Not a big job really. https://www.ford-trucks.com/forums/1...wer-motor.html
Thanks to Rich and Mike
I did mine a couple of years ago. Not a huge job but it has its moments. A service manual helps - a lot. As posted, remove the coolant lines, disconnect the blower, remove the cables and drop the heater box. The box is a tight fit, especially the heater hose nipples and firewall. A trick I saw after doing mine is to remove the mounting screws for the lower dash so you can pull it out a little to gain clearance.
Once the box is out its pretty easy to pull the core. The core itself has foam like insulating material around it to seal it in the box. Needless to say, mine was in bad shape after 35+ years. Some 1/4" x 1" (or so) self stick foam from ACE hardware took care of that.
As far as the cores, common replacements are aluminum which should be fine as long as anti-freeze is kept up. I spent a few dollars extra at Rock Auto and got a copper core which should be more durable.
Before I wiggled my heater box out, I did have to take a walk around the shop a couple of times. Patience pays off and I got it done in one evening.