Windshield Wiper Blade Basics
Changing the wiper blades is a regular season necessity. Even after changing the blades they can still chatter or leave streaks across the windshield. Here are a few tips on wiper arm and blade maintenance.
First, make sure the wiper blades park in the correct location. The left and right blade should be the same distance from the bottom of the windshield. If they need adjustment, you’ll have to reposition them at the mounting post. To do this on the 240 models simply pry off the plastic covers on the mounting post, loosen the nut with a 13mm wrench reposition, and tighten. I find that pivoting the arm off the windshield and back down while pulling up on the post cover frees the cover without breaking it. Also, with the nut loose, pivoting the arm the same way will easily loosen it from the post. Even if your wiper arms are positioned correctly, check the post nut for tightness. It is common for these to loosen.
Next if the new blades don't seem to completely clean the windshield the spring tension might not be strong enough to keep the blade in full contact with the window. It’s simple to lift the blade off the windshield and bend the slender part of the arm so it will apply more pressure. This will also reposition an arm that is too long and hits against the top of the windshield trim.
If the wiper blade hits too much on the top trim (more than 1/4”), you may have the arms reversed. There is a left and a right side. They have different lengths. If the blades still chatter adjust the arms to be perfectly perpendicular to the windshield. It’s easy to do with an adjustable wrench.Tighten the wrench onto the thin part of the arm and twist it until the blade rests at 90 degrees to the windshield.