I just finished doing the heater replacement on my 83 CJ. As many of you who have done this, it’s not hard, but takes time.
Couple things to share. When I removed the heater box apart, I purchased new stainless steel screws from Ace Hardware, nylon washers and jam nuts. I also bought a large piece of black foam (eBay) to cut replacement foam out of, one side with an adhesive peel back. When apart I compared the existing/stock heater core to the aftermarket replacement, which was aluminum and made overseas. There was just no comparison quality wise, so I too the existing core to a local radiator shop and had it record. Also, since I was planning to do this replacement once, I ordered and installed 5 new MTS cables, which are made in the USA and Very high quality. With the mts cables, the area that sort of clips into the various steel u holders is made of steel, and I used a small 2” vice to press them in as there’s no way (that I could thing of) to get them to seat. If you use the mts cables, which I am very pleased with, you need to install the lower portion of the cable to the vent box on the right before you put the heater box back in. There’s no way to press the cable into to the steel clip once the box is installed (I learned that the hard way). I had to remove the vent box (used butyl tape) install/seat cable end, and then reattach to heater box. As you probably know, the replacement fan motors are about a 1/2 inch wider diameter, which means drilling out the firewall. This was the one part of the process I kind of dreaded. I used a hole saw to do it, which ended up working well. To seal the heater box to the steel back, I went with butyl tape (eBay), and while it worked well, it’s a pain to store (it wants to clump into a big ball). Installing the heater box back in took some time, as the 4threaded posts that attach it to the firewall need to line up perfectly. I started by making sure the heater core tubes were in, and then lifted it to get that threaded post through and then secured the post with a screw (my daughter helped). After several more attempts, I gave it the old college try, and all of a sudden I could here (and feel) it seat. Lots of lifting and maneuvering, going back to the firewall to see where the 3posts were.
Started it up last night, no leaks, fan motor works great (better than original), stainless screws against the newly painted heater box gives it a real clean look, cables are smooth and one more thing out of the way.
