Wipers with a moisture-related problem.

Dear Car Talk

Dear Car Talk | May 01, 1992

Dear Tom and Ray:

My 1984 Nissan 200SX has a windshield wiper problem that none of the mechanics I have consulted seem to be able to fix. At random times while driving in bad weather, the wiper blades will first start to slow down, as though something is holding them back, and then they will stop altogether. If I do nothing they will start again by themselves after some apparently random interval of time. If I get out of the car and move the wipers they will start up also. Regardless of what I do, they will soon drag and then stop again. Sometimes I drive in bad weather and the wipers work fine the whole time. Naturally, this is pretty dangerous, not to mention unsettling. Two private mechanics and a Nissan dealer have looked it over, made some adjustments, and declared it fixed. It wasn't. One mechanic replaced the wiper motor and looked over the wiring. That didn't work either. I'm a graduate student with little money for repairs, not to mention a new car. Can you suggest some way to repair it?

RAY: Well, Linda, my carefully honed diagnostic skills tell me that this is definitely a moisture-related problem. If you simply confine your use of the wipers to dry-weather conditions only, my guess is you won't have any problem.

TOM: Now isn't that the stupidist thing you've ever heard, Linda? If you only use the wipers in dry weather, you'll ruin the rubber blades in no time! What was my brother thinking??

RAY: Seriously, Linda, since the motor has been replaced, my guess is that the wiper transmission is binding up somehow. The wiper transmission is the metal contraption that links the wiper motor to the wipers themselves. It converts the circular motion of the wiper motor to the "back and forth" movement of the wiper arms. Some part of the transmission could be sticking due to rust, old age, and perhaps general boredom (just going back and forth in the same spot for all those years).

TOM: The other possibility is that you have a bad ground. That could prevent the motor from getting the current it needs, and could also cause the kind of intermittent problem you describe.

RAY: We don't recommend trying to fix bad grounds. We simply break new ground, so to speak. Start by having a mechanic run a new ground wire from the housing of the motor to the negative terminal of the battery.

TOM: If that doesn't fix it, ask him to find you a used wiper transmission at your local "auto-recycling center" a.k.a. junkyard. And if all else fails, you can always transfer to a graduate program in mechanical engineering. At least that way, in two or three years, you might be able to figure it out for yourself. Good luck, Linda.

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