Do a search on replacing the M103 tensioner for details. Here's some links -

http://www.peachparts.com/shopforum/showthread.php?t=21133

http://www.peachparts.com/shopforum/showthread.php?t=68158

You don't have to touch the water pump to replace the belt, tensioner or hoses unless you're replacing that stub of hose between the thermostat housing and the head.

Sixto
95 S420
87 300SDL