wel i havent much experience on these type of vans but i would say there is a tensioner on the belt path somewhere if so, you need to get a socket n ratchet or a spanner of tht size and turn the tensioner clockwize this should slacken the belt enough to get it off there should be a tensioner on it, it lookes like a pulley but it will have a bolt head in the center of it to get your spanner on ok mate
muttonboi
April 2008