72 GMC heater core replacement

[Glennerd]

I am about to replace my heater core and I would really like some tips as to what may save time and what needs to come off for access. My Chilton is in the truck, truck is not here and no internet where the truck is. I have gobs of crap squishing out at the firewall, covered by what seems to be some type of undercoating. Right away, the flag is up. I am replacing the driver's fender. Someone had told me that the pass. fender had to come off? If so, not a huge deal, but I can't look at it right now. Any help would be great. Really only need a quick run through, unless there is something I don't want to know. Ha ha.

[1969~C-20~Heavy-Half]

Alright buddy first pull all heater core hoses off, and let core drain before you touch it. Then take out the inner fender well on the passenger side otherwise you wont be able to pull the core completely out. You dont need to take all bolts off the inner fender well, just the outter bolts connecting it to outter fender and inner bolts connecting it to front of frame.. 5 bolts on plastic fiberglass housing and your clear. I had a major leak in my heater core, and all it was was a crack where the outlet copper pipe connected into the core. The weld had broke. I saved myself 30 bucks and bolt some JB weld, welded up in like 3 hours and never leaked since

[Glennerd]

Thank you heavy half. I will bring 2 coffee thermos's for the job. My upper outlet seems very flimsy. It was by-passed when I bought it, and came with a new one, so she should be good and ready to come out. Thx again, kind sir.

[CountryGirlT]

I'm replacing the heater core in my '72 GMC Sierra Grande, is the process the same?

[Classic Heartbeat]

The way I do it and it works on all non A/C 67-72s is to drop the right inner fender and take the hood hinge loose on the right side fender also. Prop up both front and back of the hood. Then you have enough clearance to remove the housing from the firewall without dammaging it. Lots of guys including myself at one time do it without taking the hood hinge loose. However over time I have found it to be easier for me to just take the time and do it. Take the housing loose from the firewall and pull it off a couple of inches. You then need to take the cable loose that opens and closes the heater flap with needle nose plyers. (Try not to dammage the push nut in the process.) Once the cable is free then remove the housing assembly and replace the core inside. Be sure to get a good quality core that doen't cause you to have to alter your heater core brackets to use. I would also replace the blower motor seal at this point. If the original is still on the housing it is well past it's prime. By the way we have all of these parts in stock... Good luck.... WES