Thank you to everyone who responded to my question about this. A couple
people asked me to forward the procedure, so here it is for the archives:

Condition:
You're Vanagon runs bad when first started and runs fine after a few minutes
(after the o2 sensor is at temperature). Or, you just want to replace the
temp II sensor.

Tools:
- straight slot screwdriver (shortest handle you have)
- distilled water/coolant mix
- water from the hose
- perhaps a flashlight to see what you're doing

Estimated time:
5 minutes

Procedure:
Go down to the FLAPS and purchase a new sensor for your engine. For a 2.1L
in my 1990 it's #025-906-041-A. Make sure you get a new o-ring at the same
time (#N-903-168-02).

The sensor (on a 1990 2.1) is located on the driver's side of the thermostat
housing - which is on the front left side of the van). The connector is
hiding underneath a large hose and you can probably get to it from above or
below. This time I did it from above.

Remove the electrical connector from the sensor and stash it. Get your
screwdriver and remove the circlip holding the sensor in place. The circlip
is on the FRONT of the fitting.

Apply a little soap or WD-40 to the new o-ring and slide it on the sensor.
Reach down and begin to slide/wiggle the old sensor out. When it's about
halfway out coolant will being to flow so yank it out quickly and stick the
new one in. Check to see if the old o-ring came out. If it didn't, pull the
new sensor and stick you're finger in to remove the old one. Stick the new
sensor + o-ring back in.

Slide the circlip back in, rinse everything off and, when dry, reconnect the
electrical connection. Make sure you wash off the coolant that hit the
ground - probably less than a cup. Top up the coolant and you're done.

John Runberg
78 Champagne Edition Westy (for sale)
90 Vanagon Carat