If your water pump is on the way out you can put your hands on the water pump pulley and notice some play. You will definately feel some play. If you dont it could be something else such as the tensioner pulley bearing or alternater. Check it out for yourself if you are confident.
Good luck my friend.

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1990 190E 2.6
1996 Grand Voyager 3.3
1985 Mustang GT 5.0 5 SPD
1982 Suzuki GS 750T