95 S500 water pump,idler pulley, thermostat?s
 

I'm about to change out the water pump, thermostat, and idler pulley. This pulley is on the upper right of motor and has a fouth of the rear shoulder missing. I assume this is not correct. The pulley is also making some noise. I've never worked on MB before and was wondering if there are any things I should know before I start. I plan to replace the drive belt also. The sensors on the water pump I plan to reseal with liquid pipe dope. Any tips or info would be appreciated. I did the search and did not find anything on this car or procedure.

Just changed mine at 102k miles. .
 

and there's alot to remove to get to the water pump.

http://pages.prodigy.net/jforgione/S500_wpump.jpg

Fan shroud; poly-belt; viscous fan clutch; fan pulley and a few things I probably forgot. The timing wheel must be removed; loosen the nuts, then gently work it forward (from top and bottom) until it slides off. Then the remainging bolts on the water pump can be removed.

Also the little 'L' water hose from the Tsat: while you're in there, consider replacing it with 80C version. Can't hurt.

Good luck!