My expansion tank started leaking last Saturday while my family was
visiting the Victorville Mall, CA. We drove "Wolfie" home to investigate
the cause of the coolant leak. 
There was a one inch hairline crack just above the seam on the tank. So,
I ordered a replacement part and rented another vehicle so my wife could
get around. 
Today I changed the tank, filled the system with coolant, and started
Wolfie. Things were fine until the engine warmed up. Then, bucking,
stalling, and other bad behaviour happened. I thought that not being
driven for a week along with my spouse driving a Chevrolet might have
been grounds for jealousy. 
The cause of improper behavior is a connector on top of the air filter
unit. I knocked a wiring connector off while working in the engine bay.
Reconnected and driving went back to normal :-). So, morale is be
carefull doing things in crowded engine compartments. 

Steve Bibler
1990 Vanagon "Wolfie"