A couple weeks ago I had some people over who were getting parts from my
87' Syncro and we discussed this issue. We concluded that some non-syncro
vanagons have air intake snorkels. The intake tube runs out the engine
compartment and up the passenger rear side of the van. The Syncro, however,
has a nifty little water trap mounted inline, which isolates the water
before it reaches the air cleaner. 

Remove the rear grill on the passenger side and check for a tube. The
opening should face the rear, that way it won't suck in water directly.

Erik O
87' Syncro Westy Camper      87 Syncro 7 Passenger (PARTING OUT)
http://www.geocities.com/Baja/1965/
http://gozips.uakron.edu/~koesel/SMT/