I did my 1990 190 2.6. I didn't need special tools. I would get a new serpentine belt, a new belt tensioner along with tensioner shock and threaded tensioner rod. I removed the radiator power steering pump and belt tensioner. Don't count on doing it Benzmac's way, hes a pro. You are working blind on the two rear water pump bolts. You should have the replacement there to look at so you have an idea where the bolts are.
The biggest problems I have were with the allen head bolts on the pipe that goes to the water pump tothe auxilliary water pump on the timing chain cover the bolt would not budge. Also you may find a combination of regular hex bolts and allen bolts. Be happy if you have hex head bolts.3 and one allen.
Also the allen bolt on top requires an allen. I had to use an allen socket held in with force with a screwdriver and turned with a box wrench. Good luck. You can E-mail me with questions.
1990 190E 2.6
1996 Grand Voyager 3.3
1985 Mustang GT 5.0 5 SPD
1982 Suzuki GS 750T