I sat down in the sliding doorway of my van one evening and found the seat 
of my pants damp with antifreeze when I stood up.  What a mess.  The 
carpet and soundproofing was saturated in that corner.  So much 
leaked that it was draining out beneath the sliding door, where I park on 
my sidehill driveway.  I uncovered the rear heater (the shroud will come 
out it you just tweak the seat frame forward and have your mate lift it) 
and saw the corrosion on the fins of the heat exchanger.  The shut-off 
valve had a small drop of coolant on it, and more dripped slowly from the 
center front of the heater.  The dealer agreed to replace the heater 
core, as I had suspected it and they failed to even raise the rear seat 
when I took it in: "It passed a pressure test, Mr. Wyatt!  Must not be 
leaking!"  Today I took the carpet and soundproofing to a fire-and-flood 
cleanup guy, and he is doing his magic on it all.  And I realized that 
the greasy film on the inside of the windows was not diesel exhaust from 
the big rig that gave me a jump a while back, but antifreeze mist.  On 
the bright side, it kept the glass ice-free!  While poisoning us all.  

Questions:

The shut-off valve seems to slow or even stop the leak.  Should it?

Is my upholstery also soiled by the mist from the heater, or did it only 
condense on the cold glass?  The cloth does not appear dirty.

What might be the ill effects of inhaling the stuff for a few thousand 
miles?  

It was a balmy 25 F today in Fairbanks.  But after an hour in the carpet 
cleaner's garage, the van seemed so much more smooth/loose when I left 
(shifting, steering, braking).  It tightened up as it cooled.  Are all 
Vanagons this cryophobic?

So, if you have not already, take a look beneath the carpet back there.  
I wish I had done it sooner.  I followed the thread on this last month as 
I discovered the problem.  Any additional thoughts on the subjects of 
rear heaters and carpet cleaning are welcome.  

Cheers,

Chris Wyatt
'87 Syncro GL (for sale this summer?? 84k miles)
Fairbanks, Alaska