Checking the condition and replacing the windshield wipers (Mercedes-Benz M-Class W163)

1. Over time, road film accumulates on windshield wipers, reducing their effectiveness, so wipers should be washed regularly in a mild cleaning solution.

2. Windscreen wiper assemblies and blades should be inspected regularly. If inspection reveals hardening or cracks in the blade rubber, replace the blades. If inspection reveals nothing unusual, wet the windscreen, turn on the wipers, let them run for a while, and turn them off. Uneven marks from the blades on the glass or streaks on clean glass indicate that the blades should be replaced.

3. If the brushes do not clean the windshield well enough, the following reasons may be possible:

a) When the car passed through an automatic car wash, wax particles got on the windshield. These particles can be removed by adding a detergent with wax-dissolving properties to the windshield washer fluid.
b) Filling the reservoir with a glass cleaning fluid with wax-dissolving properties can significantly improve the performance of the windshield wipers.
c) Grease-dissolving cleaning agents are not able to completely clean glass.

4. Damage to the brushes can also be the cause of poor glass cleaning; the brushes should be replaced.

5. During operation of the windscreen wiper mechanism, the mounting nuts may become loose, so they should be checked and, if necessary, tightened each time the wipers are checked (refer to Chapters Body and On-board electrical equipment for more detailed information on the operation of the windshield wiper mechanism).