Hi.
I purchased my 1986 Vanagon a month ago.  I have replaced the right side
cylinder head gasket and have flushed and replaced the coolant.  The Vanagon
is going very well.  One strange thing though is that the left (main)
coolant reservoir sucks the coolant from the smaller (right) one - so that
when the engine is cold, the main bottle is full right to the top and the
other is always empty.  So I thought the problem had to be the cap - so I
replaced it and this has not remedied the problem.
Any ideas?
Other than this, the Vanagon will sometimes falter and run on 3 cylinders
for a while.  This condition last up to 3 minutes - then will clear up and
run normally.
I pulled the plugs and found them black - sooty (very rich mixture).
So I checked the CO using a digital voltmeter on the O2 sensor (which was
disconnected from the brain).
This showed about 0.8 to 0.9 Volts at idle (very rich!!) - and adjusting the
mixture on the air flow sensor could not alter it at all.  
My theory is that the Vanagon runs so rich that sometimes one plug will foul
- hence running roughly - then (eventually) the plug begins to fire again.
Other interesting points are that the square black cover to the air flow
sensor has been removed by a PO.......
I removed this cover myself and found some watery junk in there - which I
cleaned out.  Can I adjust the tension on the spring(ed) dial?  I thing I
need some more tension to lean the mixture out properly to at least be able
to set it using the fine adjustment on the AFS.
TIA for any help - 
Cheers MIKE
1986 Vanagon
PS:   SO far the Vanagon has done a few thousand miles - even to icy
Yosemite and has been an absolute pleasure (except for the nerve wracking
minutes when it misfires...)