valve who needs ajustment
cv joints
dead battery
cv joint or universal joint
A pebble.
clicking noise is probably fuel pump relay, check for battery condition, then for good connections including ground, inspect all fuses
Volkswagen Vanagon Official Factory Repair Manual Bently Publishers.com
if you have connected it up properly it could be just that your battery is completely flat and that when you hook up the charger some relays are getting power and making the clicking noise
probably just getting rocks caught in the tread.
you may have leaves in the fan
Because it cuts down the noise of the fuel exploding in the cylinder ! Without silencers, the noise generated from vehicle engines would be horrendous !
If there is a clicking noise get it to a mechanic you engine is blown and may be saved. Most likely you'll need a new one because a lifter is broken and it would be cheaper.
There are sites which sell all different types of automobiles in operation, and example would be autotrader. However, the Vanagon actually has it's own website dedicated to it, simply named vanagon. On this site there are links to other pages where people have them for sale.