They are pretty easily reached. All except the one between the box and the passenger fender. You will have to feel for that one, but it's still easily gotten to.

 

I -may- have found the problem. I'm no interior expert (then again, I'm not an expert at anything), but should there be a thick rubber mat covering the entire interior firewall? I've always wondered if my floor was aftermarket, and I think it might be. I cannot see anything that could be construed as a nut, bolt, or screw to get the heater box out, just a one-inch-thick rubber mat going all the way up the firewall, even behind the glovebox. If pictures are necessary to explain it, I may put them up, but I'm sort of lazy and my camera is a POS. I'm going to do some more research on this, let me know if you guys know anything about this.

 

Only on trucks with the sound deadening package. It's sound proofing.

Yep, sound proofing, it's stock. It's rubber coated and the interior is made of a fiberous material. About 1 inch thick.

The two nuts, that hold the phlenum assymbly, (heater ducts) to the inside firewall, also hold the heater box to the firewall as well. The carriage headed bolts (2) go through the heater box from the outside, through the firewall, through the two holes holding on the interior phlenum (heater ducting) and attach all together with two nuts.

The rest of the screw bolts that hold on the heater box are outside, under the hood.

 

Ohhhhh! Crap, I think I finally got it now. I was confused because somewhere else had said that there were eight bolts on the -inside- of the firewall, and I could only see two. Now I get it. Thanks for all the help again, hopefully I have enough information now to figure it out myself

 

Alright, I promise, I really am changing the heater core out (I only have about an hour or so every other day, and since it's my first time I'm moving like molasses), but I've run into another "problem," or I guess more of an inconvenience. How/Where do you disconnect the temperature/blower motor control cables? Not the electrical ones, but the control cables. Thanks again, hopefully by Friday or Saturday I can finally stop bugging you guys with my questions... hehe.

 

The cable controlling the temp runs from the dash, through the firewall and to
a lever under the hood on top of the box. This controls the amount of air that
travels around/through the heater core. If it's all stock, there'll be a small
press-on retainer keeping the cable on the lever, I've always used
needle-nosed pliers and a screwdriver to remove it. Save it for re-use.

The other cable connects to what I think is referred to as a 'blend door' and is
located just behind the glove box. This is the Off/Heat/Defrost controller.
Here again, I've always used needle-nosed pliers and/or a screwdriver to pry
the cable out of the ears of the clip that hold it in place on the lever.

You'll likely also need a 1/4" (or so) wrench to remove small bolts affixing the
cable to the surfaces near where they connect to the levers.

Experiment around on reassembly; for example, move the dash control lever all
the way to one end, then move the related control lever all the way to its
end of travel, *then* install 'em to be locked down with the 1/4" bolts. Make
sure the levers operate through their full range of motion (or a range that you
are comfortable with) as you move the controls on the dash before locking
'em down. You'll understand more when you go to reassemble it, everything
will present itself to you and it'll be more obvious. Things can also be changed
and adjusted later, it's not like things are set in stone upon initial assembly.

I removed my dash pad, it made accessing everything much easier. ;-)

-ct

 

Wow.

4 pages and 50 responses on how to change a heater core.

 

Yeah, and unfortunately for everyone involved (especially myself), looks like there's more coming. This is my first time doing anything involved with repairing any vehicle, and I'm still just a kid, so sorry if this thread is getting out of control. At least I'm literate, as opposed to most people of a similar age to myself on the internet

A. The top left nut on the exterior that holds the case to the firewall: Is there a nut behind that? If so a) how is it accessed, b) who would put a nut in such a dumb place? If not, a) how come my nut just spins and spins and spins, and b) how can I get it out?

B. The "blend door" cable has been successfully disconnected. I'm still scratching my head for the temperature cable removal, though. I know exactly where it is, but I can't figure out how to actually disconnect the cable. It's wrapped around that spinny-type thing on top of the box (that controls air flow), and rusted on. I unscrewed that bolt, and that didn't really change anything.

 

Yup Makes it much easier to read your posts, and I'm more inclined to
help if I can understand what you're saying.

By jove, I think you've figured out what I figured out on my truck!

Look at this pic (posted much earlier):


You can't see where the original pic says somethin' like "nut" but there's an
arrow pointing to it, originating near the "M" in ".COM" above it. This, to me,
looks entirely factory although I haven't looked in my service manual in a
while now. I rebuilt my engine over the summer and had tried to remove the
heater box while the engine was removed, and I ran into the exact same
thing you just did. I seem to recall seeing in some manual someplace that
you access that nut from underneath the windshield cowl(!). I decided that
was more trouble to me than it was worth so I abandoned the effort at
that point. I've removed that cowl before, while replacing the wiper motor
around 2 years ago. It's not that hard but it's a PITA of sufficient
magnitude such that I didn't feel like going there. As I remember it, you
need to remove the lower chrome windshield strip, the wiper arms, there
are some Phillips screws between the slots of the grille, and some more
screws along the front that also hold on that rubber seal. You might be able
to get away with merely removing the pass side screws and removing the
thing only enough to stick your hand/arm + tool into there. I dunno, give it
a shot and let us know how ya make out.

Somebody had earlier asked what month/year my truck was assembled, I
don't know as I'm in Chicago a the moment, I'll be back home to the Denver
area on Monday, I can look then.

Well, all I can say without seeing it is, if it's a stock config, there'll be a
small retainer on top of that skinny-type thing on top of the spring-wound
cable (the cable is wound around that skinny thing). Just pry that thing off
but, again, keep it for re-installation later. I've never seen a rusted assembly
before but I'd guess the same course of action would still apply.


-ct

 

Alright, it's all come together now! Thanks, although I now have my doubts about ever finishing this... why would Ford put a nut -there-? I'll see if I can't figure out how to get in there, but at least now I'm confident I can at least get this job done from start to finish. Thanks everybody (again), hopefully that's it for my questions.

 

Hey, Caleb, I was serious when I asked you to try half-removing the thing only
enough to stick your hand in there and letting us know if it worked, I'm kinda
considering trying that "one of these days" but I'll wait 'til I see how it works out
for you if you're willing to try it sooner rather than later. Thanks.

Yeah, I agree, it's a terrifically stoopid place for a damn nut, I more expect one
of those clip-on sheet metal nut things being there, not a damn "real" nut....

-ct

 

Which is odd, because my 1981 does not have that nut.

I bet it was installed with the cowl removed.

However on an assymbly standpoint, it was put there when the truck was being assymbled so it wasn't a pain for the factory worker anyway.

 

Yeah, that's true about the assembly line workers, I guess.. I'm going to take a look at this tomorrow afternoon, since I'm not going to have any time today. Of course I'll try the half-removal, since if it does work, it'd be a lot less to disassemble. If it doesn't work, I guess then I'll just be halfway done. I'll make sure to let you know how it works out.

 

Have you ever tried to get the cowl panel off without removing the hood? It's nearly impossible without scratching everything all up.

I got a later pinhole cowl for someone from the salvage yard, and what I thought would be a 10 minute job turned out to be a real project.

 

The only time I've removed the hood was last May/June to facilitate engine
removal. I don't recall exactly how much of a PITA it was to remove that cowl
but my paint & body is in bad enough shape that it'd be damn near impossible
to make it any worse. As I recall, it was a pain to remove the wiper arms
from those splined mounting things, that resulted in scratches, I remember
that.

Installing a hood is something that is definitely easier with two people.

When I removed the hood, I spray-painted the hinges where they attach to
the body and removed it from there. IOW I first removed the bolts holding
the side supports to the body, then I removed the bolts holding the hinges
to the firewall (leaving all hinge hardware attached to the hood). For re-
installation, I lined up the hinges in the areas that weren't covered by spray
paint. I suppose I could have just as easily used a permanent marker or
something like that but this was fast & easy.

Been looking at those pinhole cowls in the yards, I figure I'll get one someday,
too. But body work for my truck is at least a year in the future, possibly two.

-chris
colorado, usa