wipers won't park!

[von Zipper]

Hi, the wipers on my '73 911E won't self park. If I switch them off, unless the windscreen is bone dry they almost stop but then seem to 'overrun' and continue wiping.

[ESully]

It could be the contacts in the wiper motor need to be cleaned.

[edmayo]

The red/white wire to term. 53a needs to have power when the switch is off. That is what powers the park circuit. If it does then the problem is the contact in the motor it self.

[1QuickS]

I had a similar issue but I think it was the arm that is mounted on the motor shaft wasn't correctly located. As I recall, when parked, the lever on the motor shaft should be horizontal. Mine was a little off of horizontal and after I repositioned it the system was good. It might have been an electrical item like Ed suggests (I bow to his vast experience) but I think I made the mechanical adjustment and all was good afterward...it has been SEVERAL years since I resolved that issue. I think what was going on was that the kinetic energy of the moving wipers caused the motor to continue to spin after the park command was activated and that caused another cycle of wiping.

[edmayo]

Paul has a good point, you didn't say, but did this just happen out of the blue after 45 years of working correctly, or has some recent work maybe disturbed something!

[1QuickS]

Yes, like Ed said, I had wiper mechanism out and when I reinstalled it they would not park, a mechanical issue resolved by re-indexing the lever arm on the motor. Again, it was long ago and this is how I remember it.

[PStey]

I once cleaned and repacked my wiper motor after which it would not park anymore unless the windscreen was dry. After some time I discovered that because I loosened the screw that puts some pre-tension on the motor (arrow) it would overshoot the parking position. A small turn on that screw solved my problem

[von Zipper]

Thanks guys, your thoughts are very much appreciated. It feels like the momentum is carrying the motor beyond the park position and starting the cycle over - unless the screen is 'bone dry.' I stored the car for 10 years and have now re-commisioned it. Previously I had some paintwork done and I guess the wiper mechanism was taken out and replaced then and maybe the lever arm geometry as stated needs adjusting. Otherwise the electrical advice looks plausible too. I'll try the easier/simple solution first. If that doesn't work I'll look at contacts and the pre-tension screw. Many thanks again.

[PMNorris]

Could be that the nut on top of the wiper motor is a bit loose and you need to reset them back into the park position. Theres's an article in the 101 projects book that describes how to flip the park from left to right, which might do the trick. Very fiddly job though. I found it easier to access the nut by removing the speedometer.