Now in theory, living in California I could have just re-installed the original heater box and prayed it didn't leak.  But this wasn't going to work in the anal retentive world I live in.  So time to crack open that box and get it right.  Chris Blumenthal documented this process in a beautifully illustrated article in 2006 and Auto Dynamik in San Francisco has assembled a restoration kit with all the parts you need to get this job done.  Now the Blumenthal article outlines the process on a later heater box, and my heater box is the early 3 lever version with the smaller valve, so there were some differences that I had to adjust for.

Cracking it Open

Right off the bat, there were some issues.  First, the plastic bracket that holds the heater valve was cracked and when I gingerly removed the valve, a large piece between the hole for the lever and the lower bolt hole fell off in my hand, not good!  Second, I could barely turn the fan blade on the motor, so I either needed to get it freed up, or a new fan motor was in the cards.  I drilled out the rivets holding the top panel, removed the three clips that holds the rear panel to the front panel and opened up the box.  What a mess, leaves, spider webs, dead bugs and surface rust everywhere.  All the rubber grommets/bushings for the flaps were gone and all the foam on the flaps was missing in action.  I didn't want to completely strip the box, just wanted to clean it up, so I carefully pried up the 8 "washers" holding the control rods to the flaps on the front and rear box sections and left the cable coils on the control rods intact.  I did remove the cable coil on the long fresh air flap on the rear box section so all three sections could be separated.  Lastly, I removed the cable clamps on both sections so the heater control levers could be worked on separately.

Fixing the Issues

Now I could have dropped some change on the restoration kit from Auto Dynamik, but along with the anal retention is a bad case of frugality.  I bought a $10 set of grommets off Amazon which had the 6 grommets I needed for the flaps and the 2 grommets I needed for the holes for the top where the heater core outlets exit.  I started with fixing the heater valve bracket on the top section.  I used JB Weld to glue in the missing piece and repair the cracks.  Although it went back together fine and seemed pretty ridged, I though it needed additional support so I came up with a clever fix.  If you go back to my radiator hack, the two bottom brackets I used to hold the radiator are exactly the right width to fit the plastic bracket for the heater valve.  It isn't tall enough to cover the top mounting hole, but my repair was lower on the bracket.  I took this bracket, did some bending, trimming, drilled holes for the lower valve mounting hole, the lever hole, mounting holes and installed it on my top cover.

The motor was toast.  No amount of lubrication was going to get it to spin again.  When you applied 12V, the bushes would spark, but no joyful spinning.  I used the Auto Dynamik fix to purchase a Porsche Fan, Bosch, part # 0 130 007 002 for around $60 and the $6 Granger plastic computer fan, part # 5JLL6 and drilled it 15/64 for a press on fit.  Worked perfect and used the original clips to mount it back in the top section of the Heater box.  Replaced the wiring and this piece was done.

After washing out the front and rear sections of the heater box, I stuck them on the blast cabinet and cleaned up the metal pieces, checked the heater core for leaks and cleaned and painted it.  I found a grommet that fit the flaps, beveled one side to a 45 degree point and popped them in.  I bought a roll of 3" x 10', 5mil adhesive-backed neoprene foam on Amazon and cut out all the pieces for the flaps and installed them.  I had some 1mm neoprene that I used for wrapping the edges of the heater core.

Re-assembly went pretty smooth. I reattached the cables to the front and rear sections and control rods to there appropriate flaps.  The 3 clips connected the front and rear sections and the top was reattached using 5mm hardware.  The heater valve was assembled last using some 5/8 heater hose to make the connection between the valve and the core.  I needed to do some trimming on the plastic bracket to allow the lever to swing freely because the support bracket increases the thickness, but only a couple of mm.

Installation

I'm waiting on some parts (defroster nozzle for the driver's side and some bezels) so I can finally install the dash, but the heater box will go in next week.

Thanks for reading,

Mark