Why does the driver side windshield wiper always go bad first?


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Hello Diner. Scientists–even those who are Fortune Cookies–need to take a conservative stance. Eyewitness testimony is most unreliable because of confirmation bias. The witness sees events that support conclusions the person has already made. Large number of samples and control groups eliminate this issue.

But let us assume that we took those measures, and the driver side windshield wiper does indeed always go bad first. It may be that the position of the driver side wiper blade puts it closer to the engine block and therefore in a hotter location. Driver side wiper blades are sometimes located over the exhaust vent that is close to the hinge-side of the hood. Wiper blades work best when they’re soft, and the additional heat from a hot engine block may be baking out (and embrittling) the driver side wiper faster than the passenger side one. Another contributor could be from the sun. The passenger side wiper may get more shade when the car is parked. UV radiation accelerates the embrittlement process, and the shade may help maintain the softness of the passenger side blade.