Pulled all the rear panels today and insulated with the foil-wrapped bubble wrap stuff. You don’t want to use fiberglass or that cool foam in a can stuff because they both trap moisture and hold it against the metal. Even the bubble wrap requires care – front doors need to be able to drain water that gets in around the window, so they’re best left alone unless you fully understand the drainage/vapor barrier setup in there (I don’t yet).
The insulation was great to work with. You measure the spaces, mark material with sharpie, cut it with a plain old scissors, spray some adhesive on the back of it and on the mounting surface, and stick it on. Once the glue is dry (5 mins), use impermeable pressure-sensitive tape to seal the joints and edges so you don’t create water traps. I don’t know how you’d do this in a humid climate, but it was easy here in the dry winter.
After all the walls were insulated, I popped the panels back on and turned to the evil Vanagon rear heater of death from hell.
HOW I REPLACED THE EVIL VANAGON REAR HEATER (WITH A REBUILT EVIL VRH)
C-clamped the two hoses coming through the firewall to seal them off, loosened the hose clamps holding them to the heater, pulled them loose (a little drippy, have paper towels handy).
Unscrewed heater from the floor, unplugged the wiring harness, and turned it hose side up so it wouldn’t gush. Brought it inside and exchanged it for the rebuilt one.
Collected hoses to new heater (but kept them clamped off – important!). Made sure valve on heater was open and used a small funnel to pour coolant into the heater through the bleeder valve hole. Tapped, tilted, pinched hoses, and worked the shutoff valve back and forth, adding coolant until I was satisfied there was no air in the heater.
Lifted heater up a bit, so that any remaining air would rise to the bleeder valve from the hoses, and removed the c-clamps. It took a tiny bit more coolant. Screwed it back down to the floor and wiped it off so it would be easier to see if this worked or not. Closed the valve on the side of the rear heater.
Started the van and ran the engine till warm, then slowly opened the valve allowing hot coolant to flow through the heater…no leaks so far! Turned on the rear heater fan and it works GREAT! It’s almost too effective; the front heater was noticably cooler with the rear one going.
It was about 30 degrees out, and together they warmed the car completely almost immediately…and it seemed to hold the heat longer with the new insulation.
Also, I replaced a couple of door locks so there’s some way in other than climbing through the rear hatch. That’ll be nice!
While I was doing all this, the Mr Heater Portable Buddy kept me nice and toasty, running on low maybe 1/4 of the time with the sliding door opened a crack for air. I spent hours out there and the 1 lb propane tank still feels pretty full.