1999 s320 serpetine belt
 

Can't find any info on the 99.I need to change belt.I'd like to know what tools I need to move tensioner in.Also belt routing.

Thank You

All I can give you is E-class but it might be the same -

Routing diagram would be near the back of owners manual if you have one. Examine area under tensioner pulley. There should be a 17mm hex at about the 7 o'clock position. If so, put a wrench on it and turn counter-clockwise to pivot away from belt and slip it off.

Maybe make a diagram of current routing before taking it off? :wink3:

Also, check manual for the length of poly-v belt. Some engines have two lengths depending on which options.

Mine has straight six engine.Thanks 17 star

Correction
 

1999 s320 belt tensioner uses a 15mm socket.Best to align belt except for alternator,and pulley,then pull tensioner and slip on alt,an pulley.

you may want to look at replacing a tensioner while you have the belt out. believe that's an 8mm allen socket shorty. Also, remember to loosen that allen bolt on the tensioner pivot before using your 15 mm to loosen the tensioner off. I stripped mine out because I didn't do that, and needed a new tensioner adjustment arm too....

Mine did not need anything losened.99 is alot different,usally last car from chassis's are user friendly.