Windshield wiper not parking problem

[Frank McCaffrey]

I am having problems with my 1968 280sl wipers not returning to the parking position. Where should I start to look for the source of this problem? Thanks for your help. Frank

[al_lieffring]

frank

when you shut off the wipers do they always stop in the same position or just stop where ever they may be when you push the stalk switch?

[bpossel]

Frank,

If your wipers are just mis-aligned, you can reset them properly by disconnecting the wiper mechanism from the motor.  Look under your dash on the passenger side.  One bolt (8, 10mm?) connects the wiper to the motor.  Disconnect the 2 pieces.  Also, remove your actual wiper arms themselves.  Next, run your wiper motor for a few seconds and then turn it off.  It should now be in it's "parked" position.  Reconnect the wiper motor to the wiper mechanism under the dash.  Re-install your wiper arms in their proper position.  Test wipers to see results.  In most cases this will correct the issue of mis-aligned parking of the wipers.
Let us know how this turns out.
Bob 

[Frank McCaffrey]

Thanks for the replies. The blades will stop in the location where they are when I push the stalk switch. Thanks Frank

[graphic66]

Sounds like the wiper relay located on the drivers side inner fender under the hood. You can open these up and clean the contacts and check them out pretty easily. Mine wouldn't shut off all the time. Also, if you pull the linkage off the motor use Loctite Stud and Bearing mount on the shaft to lock it in place. As overbuilt as these cars are that little 10mm nut on that small shaft are very taxed and can slowly slip.

[al_lieffring]

There is a switch and cam inside the wiper motor that stops the motor at the same "parked" position when the switch is shut off, Pin #4 on the wiper motor plug should have power all the time when the ignition is switched on, number 1 should be getting power from the wiper relay when it is switched on. The relay turns the motor on and off, but doesn't controll the parking function.

This is one of those jobs that I know I did 30 years ago, but I just dont rembemer the details. The parking switch from what I remember is inside the motor gear train, and the motor needs to be removed and disassembled to get acess to it.

Al

[Naj ✝︎]

Here's a pic:

naj

[graphic66]

Al, thanks for correcting me. You are definitely correct. My memory of the bad relay was incorrect. My wipers wouldn't shut off because of the relay, not a parking problem. My parking problem was the wiper mechanism slipping on the wiper motor shaft. Once that happened it ground off the serrations on the motor drive shaft somewhat and using the Loctite Stud and Bearing mount on it stopped it from moving. Now, on my Mercedes 406 Unimog the wipers stopped parking after I followed your great advice on lubing the wiper spindles and linkage. My guess is that the inertia of the wipers, because they move so easily now, causes them to go past the "dead" spot and keep running. I haven't really checked it out though.  They stopped acting up lately. I think they may be drying up a little and getting more friction in the system.

[al_lieffring]

On the Unimog,
there are some wiper systems where the parking switch momentarially short across the motor windings to act as a brake to stop the inertia of long wipers from rolling past the parking spot.

It is possible that the grounding (brake) contact on the parking switch is dirty and not always making contact.