Let there be... HEAT!

As the temperatures have dropped due to the fall, the more critical the frozen heat control lever on the console of the 280z has become.  When I purchased the car, the heat selection level was very stiff and essentially wouldn't move.  I was successful in moving it once or twice when the engine was warm, but being the summer months I didn't worry too much about it... until now.

The heater control valve on the 1976 280z is very rare.  So rare in fact that the only way to obtain a refurbished unit is to trade an existing core in good condition.  My first thought with my car was that the heater control valve was bypassed since the lever didn't move.  The only way to find out was to start disassembling.

After pulling out the dashboard, console and blower motor, I was ready to pull the blower housing.  I live and learn and spent too much time unbolting the blower housing from the cowl duct which was not necessary.  The three bolts securing the combined assembly to the body are all that are need to be removed in order to pull out the entire unit; simply pull down after removing the bolts.

I then scraped the 40 year old goo from the cowl mating surface where I will later create a custom gasket from self-adhesive weatherstrip.

After removing the blower housing I was able to see the heater valve, which to my surprise was still intact.

At this point I freed the valve by applying a bit of force on the valve actuator.  I then opened the valve and let the car run to operating temperature.  To my dismay I saw coolant seeping from the top of the valve, which means that I need to replace it.  After considering my options and discovering that to remove the valve and capillary tube as a whole (in order to send it in as a workable core) I would have to disassemble MUCH more of the car, I decided to follow the guidance of a forum post my father sent me.  This blog post recommended just scrapping the old valve and adapting an inline valve which had the added benefit of greatly simplifying the hose routing.  

Before tackling the new valve, it would be senseless to be this far into the heating system and NOT pull the heater core.  I once again drained the cooling system.  In order to clear the coolant from the heater core, I created an adapter to blow out the lines.  With a small amount of air pressure applied through the heater core I was greeted with a spray of funky fluid into my engine bay.

Luckily at this point it was a simple as pulling a couple of screws and sliding out the core.  I'm glad I did, as there was a bunch of trash accumulated on the core over the years.

After cleaning the outside of the core, I started cleaning out the inside.  I did this by pumping water through the core in reverse of the normal flow.  The first couple of flushes revealed a LOT of crud, but after a few bucket changes things began running clear.

I was also checking for leaks during these cleaning cycles and was happy to find none.  Much like the heater valve, the heater core for the car is quite a rarity.

I ordered a Four Seasons heater valve (#74267) from Amazon.com and received it the next day.  I also order two 90 degree molded heater hoses (Gates #28466).

After lining up the parts under the dash, I realized quickly that the new heater valve was too long.  In order to make things fit, I trimmed all tubing after the barbs on the value, which shaved about 3/4 of an inch off the total length.  This gave just enough clearance for assembly.  In order to adapt the control cable to the new valve which only has a post, I looped a piece of aluminum back on itself and drilled a hole for the cable.

After reinstalling the firewall passthrough and the heater core into it's slot, I cobbled the new valve assembly into place.

Reinstallation proceeded without any hiccups.  After a test run of the car and no leaks appearing, I finally have heat in the Datsun!