So the winter's here, and it seems that most of the threads are about engines running crappy because of incorrect choke settings and the other problem seems to be only kind of hot heaters.
Most of this is because of missing foam in the heater body or 180* thermostat.

Here's how to fix that foam problem. I have no a/c, and a high output heater. Yours may look different.

Materials:
Red RTV and some pipe insulation (by the hot water heaters at your local home improvement store.)

(this particular foam is rated up to 270*, you don't necessarily need it that high, just higher than your thermostat)

1-Drain your heater core, disconnect all the wires and tape them off. Undo the 3 nuts on the engine side of the firewall that secure the heater body to the firewall.

There's a good chance you'll spill a little coolant on both sides of the firewall.


2- Disconnect the 2 control cables and blower motor wire connector from the heater body. You may have to slide the heater body out and down a little to remove the OFF/HEAT/DEFROST cable. They simply unscrew.


3-Take the heater body out of the truck. It should like something like this on the backside, which is how you get into the heater core (there should be 4 7/32" or so nuts holding the backing plate on.)


4-Take the heater core out. If yours looks a little different, thats OK. It might just be the regular heater vs. the high output heater. Either way, if it has NO FOAM, thats why your air is lukewarm at best. Air is moving around the sides of the heater core instead of through it. Mine had no foam because the last heater core leaked, and when I put the new one in the old foam was full of coolant and I thought "heck, I don't need this foam" and didn't give it a second thought. Thats probably what your PO did too.


5-Cut up your pipe insulation into strips that will fit around the heater core and seal off the leaks. You may have to play around before you can actually get it to fit in and put the cover back on. I put red RTV on there in the hopes that it won't free up and blow around. Whatever you use, make sure it can handle the heat. This is what mine looked like.




6-Put the cover back over the heater core body, and then button her back up. Make sure that when you are putting the heater body back on the firewall, you push the wires for the blower motor through the firewall first. Otherwise you can shear off the wires (don't ask me how I know this). Connect the cables and wires, then put it up on the firewall. You may have to give it a wonder jiggle or two before it all lines up. Bolt the body back to the firewall (engine side). Connect the two hoses, and reconnect the wires for the blower motor. A little dielectric grease couldn't hurt.

7-Let the RTV or whatever you used set for a little while before you use the truck (or at least the heat) again.

8- Enjoy your newly rejuvenated and unbearably hot heat

 

Good write up. I did the same thing on my 79 but used Adheasive Weatherstrip I bought from Home Depot. It comes in a roll and I put a few layers around my heater core and it works great. I was stuck with sub par heat for some time. Now it works great so I can drive it all year long.

 

Nice job, and pics too! Thanks for contributing to FTE.

 

Awesome thanks just getting ready to do this in my truck waiting for a nice day to do it!

 

Nice write-up and good pics! Mad props to ya!

Josh

 

I just did the heater core on my truck for the second time and guess what, it has no foam! I don't have a problem with the heater in my truck but I'm sure it could be better after seeing this. Great job!

 

great old post thanks for digging it up first pics ive seen in 3 days of digging