As part of my 79 resto-mod, I needed a factory heater box. Since these are only available used, I went to E-bay, where I got a good deal. Once it arrived, I saw some things not readily apparent in the pictures. There were a lot of cracks, the box was misshapen from being over tightened, and the outlet flap seal was missing. It needed some repairing so I thought I would post the repair process for others considering trying this.

After disassembling the box, I removed the inlet air flap from the core frame and bead blasted the core frame and straightened it out.





I painted the inlet flap door to prevent further corrosion and put it back into the core frame



I used a dremel tool with a 1/16" spherical engraving bit to remove the cracks and ruined material.





Then I used a heat gun set on low to soften the fiberglass and some clamps to straighten out the deformed edges




Before heat





Clamping after heating





After cooling

Many of the screw holes were stripped out and shattered and there wasn't much left after I removed the ruined material. Rather than reglass and retap the holes, I decided to use nut inserts. I found some 10-32 nut inserts that were 1/4" diameter and 1/2" long. I drilled out all the holes and glued these in their place.




After material removal





1/4" diameter 10-32 nut inserts





Nut inserts in place






Ground out crack and nut insert


I made a structural putty from epoxy, colloidal silica, and 1/32" milled glass fibers. I filled in the cracks and holes, let everything set up, and used pink grinding stones and sand paper to shape everything.



The outlet was broken, which allowed me to remove the flap. I used a sheet of adhesive backed neoprene to fashion another seal.





Pattern fit check to flap





Pattern fit check to box





Seal halves





Seal halves set on flap by placing adhesive side together

I put the flap back in place, fixed the large outlet crack and reconstructed the missing piece of the outlet flap.





Foil backing on work area





Structural putty globbed on to missing section.





Outer edge after shaping





Inner edge after shaping

Finally, I powder coated the vacuum actuator bracket, painted the box, and put everything together.





Seal working and held firmly in place by actuator





Refurbished bracket and new hot water cut-off actuator





New heater coil

That's a brief overview of what I did to restore an old heater box I bought off of E-bay. For a more in-depth description of the steps involved, or to look at some of my other work, please feel free to visit my corvette resto-mod site:

http://www.dans79corvetterestomod.com

You can contact me at that website or on this forum. I welcome any advice and feedback, and I hope you enjoy the site. Thanks.

MajD

 

Wow - you must've had a crazy talented assistant helping you !

 

Great job!

 

So often we have to be creative to solve the problems in these cars. I had to do some of the same things to mine when it was out. You probably did it already. But check those vacuum canisters for proper operation while you have it out. I can't believe it but all of mine were functioning correctly. Great work!

 

Thanks. I did check the canisters and was glad to discover they worked. New ones are not cheap.