windshield wiper "parking"

Searching the 164 forum for “windshield wipers” turns up a myriad of posts on the incorrect sweep of the wipers, either overshooting or acting erratically. I’d suspect that if we took a poll on wiper "parking", probably about half of the BBers would say they have the problem while the other half would ask "what's that?" 

Thanks to our dear friend Alex in New Zealand for illuminating this subject to me (about six months ago), Alex and I are now pleased to share our experiences on how parking works and most importantly how it can be restored without even removing the wiper assembly.

First, to those of you who may not be acquainted with the design, here is how it works:  

1) in OFF position the wiper blades should be partially hidden under the rear edge of the hood, almost completely out of the driver's sight line, each wiper arm resting or almost resting against the black washer nozzle, a post which acts as a sort of stop.

2) turning ON the wipers, they first do an initial sweep that is about 2 1/2 inches short of a full sweep; coming down they stop about 2 1/2 short; from then on they sweep between this "raised" position and a full sweep.

3) turning OFF the wipers, they go first to their full open position, then on the downward sweep they go 2 1/2 inches further, stopping in their “parked” position under the hood area. (the motor/circuitry actually has a “reversing” design)

If yours don’t do this—and barring some other possible problem including electrical—the fix may simply be a matter of removing the crank arm from the wiper motor, disassembling the intricate plastic ball joint, sanding it down, and popping it back in place with new plastic-to-metal grease.

First, remove the thin black plastic cover that hides all the HVAC components; remove one 10mm bolt holding left wiper bar to crank arm; remove one 13mm nut (and washer) from motor, and pry up the crank arm with a blade screwdriver (while wiggling the arm with your other hand) and remove it from the splined shaft (to aid in the reassembling, note position of arm!) This is really quite easy: 1 bolt and 1 nut!

Here is how Alex describes the mechanism:

"The motor crank has a special eccentric clutch (under the black plastic cover), made in Germany with the usual German complexity. When the motor runs in reverse, the eccentric flops around so that the effective length of the crank changes. That puts the wipers down to their lowest position. When the motor runs forward, the eccentric should go back to the previous position so that the wipers park in a slightly-raised position between sweeps.  At its core, the eccentric is a plastic balljoint with an offset pin running through it. The problem is that the plastic balljoint becomes really stiff as the plastic seat hardens with age, and no longer spins around as intended.

The solution I found is to take it all apart (a very small 'E'-clip comes off the pin) and pop the centre out of the balljoint, which takes a couple of hammer taps in the right direction, and then sand it down (280-grit sandpaper, etc.) so that when it is popped back in, you should be able to turn it around with your fingers. Don't bother trying to remove the seating from the metal arm - it has probably become far too hard to remove.

There is also a spring-loaded plastic pin that creates a one-way ratchet, necessary to make the reverse rotation move the centre. My plastic pin had a broken spring, so I cut down a spring from a ballpoint pen to replace it. When you put it all back together, use some silicone grease and make sure the E-clip goes back on the pin properly."

Alex provides this picture of the assembly (n.b. the dust boot has been removed on right side):



And here is my photo showing all the parts (degreased), laid out in exploded fashion (n.b. the same dust cover boot is not shown):




I actually used 220 grit sandpaper to sand down the ball and then “polished” it with 600 grit, however I had to do it three times in order to get the right, somewhat loose, fit (Alex probably did it once). Note that the tapping out of the ball is best done laying the metal crank on an open vise, with each edge cradled by the vise; tap the short side of the ball with a rubber mallet or the wooden handle of a hammer, it takes only a slight tap. (remember you are dealing with 20-year-old plastic!).

I reassembled everything using generous dabs of white Molykote 33, the best product for plastic-to-metal fittings, rated for very cold temperatures, and easily found online. Popping the ball back into the socket can be done with your thumb. Be sure that the hole where the little pin slides in is clean and greased.

One important advice: don’t forget the top rubber seal on the crank arm before you reassemble the arm in the car—you may not be able to attach the seal in the car, I couldn’t, and had to remove the arm again. You will probably have to readjust both wiper arms to get them perfectly regulated. Then give yourself a treat—invest in new blades. If I am able to ascertain if the crank arm assembly can still be sourced somewhere new (who knows, miracles do happen), the information will be posted to the BB.

Good luck and happy parking.