Today while driving in the rain, the left hand wiper stopped, then started, then got itself out of sync with the right one and jammed the two together! (Note this is a RHD vehicle, so it was the passenger wiper that went nuts)

The wiper can now be moved by hand, with slight resistance.

What's going on here?

Is it a common or easy thing to fix, or do I need to subject myself to a cashectomy at the local Vo dealer (again)?
--
--1996 940 Turbo wagon

Dealer: drop off car, leave for at least a day, pick up to find $100 diagnostic fee and repair charges.
Self: Read 700/900 FAQ, re-tighten nut per Spook's instructions, spend savings on beer and a great afternoon.

I had a similar problem with my 960. The nut that holds the wiper arm at the base gets loose. The wiper arm fits over the shaft that protruds from the cowl with spline fittings, and I think the spline is tapered, if I remember correctly. When the nut holding the arm to the shaft loosens, it allows the arm to move up the shaft under motion. The wiper arm meets resistance and can momentarily stop while the shaft continues to turn. Then the wiper arm is repositioned (incorrectly) on the shaft.

Flip up the cover over the nut on the base end of the wiper arm, loosen the nut, reposition the arm, and tighten everything down. It's an easy fix.

Good luck,

Robert

Dear Mike,

May this find you well. What likely happened is that the passenger-side wiper arm worked loose, because the hex nut that holds it worked loose.

At the bottom of the arm, there is a black plastic cover. It covers the hex nut.To tighten the nut:
(a) Grip the cover between thumb and index finger.
(b) Gently rotate the cover upwards (clock-wise)
(c) You will see the hex nut.
(d) Set the wiper arm in the proper position relative to the driver-side arm, which did not come loose
(e) Tighten the hex nut.
(f) Check the driver's side wiper hex nut.
(g) Check these nuts every oil change (or more frequently, if the wipers get a lot of use).

There is a possibility that the loose arm stripped the teeth on the insider of wiper arm's mounting hole. If so, tightening the hex nut will not keep the arm in synch with the other arm.

The wiper arm mounting is made of aluminium, so is easily stripped. The use of aluminum is intentional. If the arm jams, the aluminum strips, protecting the wiper transmission and motor against damage. Replacing those involves a major "cashectomy" (great term!!!!).

If tightening the hex nut does not keep the passenger-side arm moving in synch with the driver-side arm, replace the passenger-side arm. You can get one at a salvage yard at low cost.

When installing the replacement arm, align it properly, and try to get the teeth on the inside of the mounting hole, to align with the teeth on the splined shaft.Tighten the hex nut.

Hope this helps.

Yours faithfully,

spook