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1989 K5 Heater Core

Recon!

Recon!

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Columbia, SC
I took delivery of my K5 today, and the heater core promptly exploded. I am having a very rough time replacing the heater core because I can't find all the bolts to get the distribution box off the firewall. Can anyone hook me up with tips on how to make the replacement easier on me? It's my first heater core replacement, so it's kicking my butt.
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you can get to the lower 2 speed nuts with the well in.

IF you know where they are.

IF you have the right tools... a small mirror, 1/4 drive extension and ratchet, a universal and socket, or swivel socket..

and IF you have some patience..
 
I have an 89 K5. Replaced the core twice. Never pulled the fender to get to the bolt on the bottom. You can easily get a 1/4 inch or 3/8 with universal joint socket on the nut witout pulling the fender.
Also there is a nut on the inside of the firewall you have to take off
 
Provided the fender liner isn't rusted to **** just drop it.

My buddy and I did mine back in October and I can't imagine doing this without the fender well gone. I do have AC though and the "suitcase" made life VERY hard on us. Nothing was as simple as Chilton's or GM made it sound like in the repair manuals.
 
Changed the heater core on my 89 in less than an hour without pulling the wheelwell. There is a bolt down low and it can be gotten with a 1/4" drive and a swivel and socket.
 
I went to Home Depot and got a swivel for my 1/4" ratchet.
I know where one of the nuts is on the bottom, but I can't seem to find the other(s).
Where is the one on the inside? Is it to the far right as you look towards the front of the truck from the seat? The one I'm thinking of has a wire guide/loom/clip thingy on it.

I have A/C, and my inner fenders are immaculate. Kind of weird since the floor pan is so rusty. And that's the only place it really has any rust, besides the tailgate that is.
 
I usually punch an access hole in the inner fender. 1" diameter hole saw and then when the R&R is finished. Paint the bare steel edge and pop a hole plug in it.

If you ever have to do it again, your task will be much easier.

Shoot straight if you go this route!
 
4X4HIGH said:
Changed the heater core on my 89 in less than an hour without pulling the wheelwell. There is a bolt down low and it can be gotten with a 1/4" drive and a swivel and socket.
Click to expand...

Yup as I said in eariler post. You dont have to pull the wheel well. Waste of time. 1/4 drive and swivel will work fine.
The first core took be a bit longer than an hour but the second was about an hour.
To get to the nut on the inside you have to pull the glovebox. you will see it on top of the box.
Then you have split the box apart. There are a bunch of small screws holding the halves together.
There is some heater control linkage you may have to disconnect also the get the core out. Depends if you have AC or not.
 
What a serious pain in the ass. The distribution box was a nightmare to take apart because of all the vacuum actuators and the rods in the doors. But, I got it all done. Hopefully I never have to do that again. The box and all the ducting was surprisingly clean for a 20 year old truck, only dust on the inside, and the water moisture where the core went kablooey. I broke off one of the stud/speed nuts, and since I didn't have anything to put in its place, I am one step away from completely finished. I tested out all the heater and a/c settings in all positions and everything works flawlessly, so I know I put it back together correctly. I didn't end up taking the inner fender off, the swivel was all I needed to get to that one speed nut. And of course, that's the one that broke.
 
What is the best stuff to use to seal the box back up withand to the firewall?
 
heater core

i have done several and the cardboard like padding kinda holds back any air leaks and keeps unit from bottoming outagainst firewall. if you are missing this i would use several layers of self sticking foam padding the kind ac and cooling contractors use. it come in different widths and thicknesses. or make a gasket out of a piece cardboard then put some padding on top so it can take up space between firewall. this will take up the high and low spots. you might have to use some spray adhesive to cardboard and padding together.
 
cybrfire said:
I usually punch an access hole in the inner fender. 1" diameter hole saw and then when the R&R is finished. Paint the bare steel edge and pop a hole plug in it.
Click to expand...

I wanted to do this sssoooo bad the last time i replaced my heater core (2nd time in 4 years- no more used heater cores!).
If I ever do it again, I will do this.
 
Teck said:
What is the best stuff to use to seal the box back up withand to the firewall?
Click to expand...


Engine side of the firewall?

I get a can of the rubberized undercoat that they sell at every parts store/ wallmart, and spray a nice thick coat over all the seam that I can reach. Bam! just like from the factory in 30 seconds for under 8 bucks.

That reminds me, I need to go do this right now.
 
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