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Heater Box... Easy As Pie!


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I have been putting off rebuilding my heater box for ages. Finally, today, I decided to bite the bullet and go for it. After psyching myself up (nearly took me screaming at myself in the mirror to get the courage), I went out to my car and was prepared to be laying in a pile of parts screaming "WHY!?" at the gods of speed for giving me such a torturous task. Then about 40 minutes into it, the heater box was out, on the sidewalk, looking back at me wondering why I had waited so long to take it out. I took it apart without issue (seems it had been rebuilt, poorly, back in 83 according to the sticker on the motor, so it wasn't riveted but only screwed together), brought the heater core to my favorite rad shop (got stuck in traffic for hours, but that doesn't count), and 50 bucks poorer they told me it would be ready the next day. Went home, replaced all the foam and grommets (by the way, I'm selling all of the foam you'd need, really high quality, as well as the rivets and grommets), and got everything cleaned up ready for final assembly. 


Okay, I will admit I don't have a center console or under dash panels, but I really don't see what the fuss is all about. I've put this job off for so long thanks to all the horror stories. I suppose this thread is meant to be some encouragement for all those who are putting off that job because you think it's going to be a royal pain... 



Just do it. It may be a lot easier than you're expecting and the rewards are fantastic. 

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(by the way, I'm selling all of the foam you'd need, really high quality, as well as the rivets and grommets),





I need to put this back together.  I was cleaning it tonight.  Unfortunately the half that holds the fan is totally cracked and won't hold the fan.  I am also have issues getting the blade off the fan motor shaft as my motor is shot and bought a new one from Blunt. I just bought another on heater box on ebay from Hawaii as it was the only one I could find. Hopefully it is all in good sorts.


I'd be interested in seeing what you are using for foam/grommets/etc.  As soon as the new box come in, I need to tear that one down and make one good box out of the two and need all that stuff.


Should I bring the core to the rad shop if is doesn't leak?  I guess if it's out I might as well.




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Paul--easy way to salvage the fan for your new motor.  Saw the end plate off the old motor, then extract the armature.  Cut the armature off near the fan hub, then place the armature shaft stub in an appropriately sized socket and use a drift or punch to drive the armature shaft stub out of the fan hub. 


Be sure and measure how much armature shaft protrudes from the fan on the old motor so you can position the fan correctly on the new motor.  And don't install the fan so the blades suck instead of blow!



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mike has the right idea for removing the fan. be careful with it, use a lot of penetrating liquid to help free it and PRESS it out, don't hammer it. 


Absolutely absolutely have the heater core refurbished at a good shop. Have them flush it, pressure test it, repair any leaks,  strip it and paint it in radiator paint. No point doing all this work only to have the core spring a leak a couple months later. 


As for the foam, I have two sizes. The thinner width but thicker foam (two strips of it are used inside the heater box) has the following dimensions:


Weather-Resistant Neoprene/EPDM/SBR Foam, Adhesive-Back, 3/8" Thick, 1/4" Width, 25'Length


And the wider stuff that goes on all the flaps has the following dimensions:


Weather-Resistant Neoprene/EPDM/SBR Foam, Adhesive-Back, 3/16" Thick, 1-1/4" Width, 50'Length


You will need to lay strips side by side to completely cover the flaps. The adhesive is extremely high quality; be sure that you have it aligned properly before you press it down because it won't come up without a fight. It's easily trimmed using a razor blade, and I use a rough file to round the edges in the places where the flaps have some trouble closing. Also, it's not a bad idea to use some C clamps to close the main flap for 10 minutes or so in order to imprint the shape of the flap edge into the foam in order to speed up the break in. 


I will provide enough length to do everything and then some extra in case you mess up. I have a LOT of this stuff, and I barely used a foot of each roll to do it. 


As for the grommets... the larger size is used for the hinges, and the smaller size is used in a few other places. Again, I have hundreds of these things. Same deal with the rivets; I have a box full of them and they are very high quality rivets. Be sure to clean all parts properly with a brass brush and a solvent to remove all the old glue, and reassemble using some grease on all the hinges. Oil the heck out of the cables while your at it... When your done it should be effortless to use the controls. 


Push-in Grommet, 1/4"id,9/16"od, 1/16" Thk For 7/16" Dia Panel Hole 


Push-in Grommet, 3/16"id,13/32"od,1/16"thk For 5/16" Dia Panel Hole

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I use brass pan-head bolts, washers and nuts to put the cover back on my heater boxes.  No more drilling out the rivets.


For a job that only needs doing once every 20 years, Rivets provide a little piece of mind since they won't come loose under any conditions. 

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I use brass pan-head bolts, washers and nuts to put the cover back on my heater boxes.  No more drilling out the rivets.

+1, but I used stainless with stainless ny-lock lock nuts.  I recently had to rebuild the heater box in my '73 tii because of a pinhole leak in the heater core.  Was glad that I had used the bolts the last time I was in there about 5 years ago.  This time a new heater core, rebuilt valve and fan was used.  I also made a pressure testing rig to make sure it didn't leak before I installed it.  Here's some pictures:













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Your box is a lot prettier than mine. mine has a lot of overspray still on the top cover, but since the car is a daily driver and sees a lot of abuse, it's back in now and working beautifully. That pressure test rig is beautiful also. 


It's also really nice to have working defroster vents... I can't wait till it rains so I can try them out :)


Does anyone have a source for the nut that attaches to the heater valve? Also I am having some trouble getting the heater core to fill up... ran the car till it heated up and thermostat opened, but the coolant level didn't drop any. The inlet is getting nice and warm so fluid is flowing into it, but I get the feeling it is not filling up completely since the outlet is staying cold. I'll try to fill it with a turkey baster and see if that improves things at all. 

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