Heater core R&R 1974 CJ?

How painfull is it to R&R a stock heater core in a 74 Renegade? I'm taking it hunting with me next month and the warmth would be nice. These damn things always fail right before winter. I dont have a factory service manual so I will be winging it. It looks like an easy job but:?

 

Not terrible. There are about 4 or 5 nuts that hold the heater box on that can be accessed from the engine side of the firewall. Once the box is out there is an access plate with about 15 or 18 screws holding it on and a clip that holds the blend mix door on. Once the plate is off you've got access to the core, which just slips out. I've got the dash panel off of mine so it was easier to see everything, but it's not all that difficult.

 

I would not be scared of doing it on the CJ wait till later on a TJ or a S10 or any new car, those are fun. CJ is pretty forward, no hidden parts.

 

Thanks to Nwedgar making the factory service manual available there is a great exploded diagram available here: http://warloch.com/74Manual/13 - Heater and Defroster.pdf

 

Replacement core probably won't have any kind of foam border like the original. I wrapped mine with the kind of foam used to seal pickup truck caps but not as wide. I also sealed around the back cover with a thin bead of plumbers putty. Packed the same junk around the inlet and outlet ports so it smooshed out when I pressed the heater box against the firewall.

While you have it out I also recommend sealing up the duct to the defroster as much as possible. Mine had some splits and gaps where it connects to the top plenum. If your heater box is like mine there are two holes pointed toward the defroster but only one is ducted. Blocking off the other will send more air to the winshield.