you drive a 318? M42 right?
what do you need to do exactly , remove the belt? or remove the who assembly,
if its the belt you need to get an allan wrench and turn it (i believe ) clockwise to release tension and slip the belt out, now i think the M42 has the tension pully mounted on an arm that is one piece , im sure you can remove just the pully but if there is a problem with that particular part of the belt system than you might as well replace the whole thing which can get a little tough (well my M50 was tough to do on my own)