Wipers won't park

[newforest]

1966 3 litre MKIII

Hi, the wipers on my car won't return to the park position, they just stay on the screen wherever they are when you turn the switch off.

It's not entirely clear from the wiring diagram in the maintenance hand book how they work. I assume there must be a permanent live to the motor assembly as well as the live from the switch and then presumably a microswitch inside the assembly to cut the power once they have reached the 'parked' position?

Only just got the car so can anyone advise the most likely cause or the best place to start.

Thanks

Pete

[Phil Nottingham]

There is a semi permanent live from the special on/off switch - the self park points under the motor cover may be corroded. The parking position is adjustable via the knurled knob but it should not need it unless it has been messed with.

[johnwp5bcoupe]

I would change the switch first before doing anything else as long as the wiring etc hasn't been messed with?

[3litrekiwi]

Hi Pete

l too have a 66 Mk III. When I bought the car the wipers were not parking either. I agree with John, my switch was faulty and the car came with a spare so an easy fix after I had stripped the wiper motor to find nothing wrong. Replaced the switch and all good other than losing my speed control. I think the spare was from a Mk I. I will investigate at some point but I try not to get the old girl wet if I can avoid it.

The wiper motor/gearbox is an interesting bit of design. The park is achieved by reversing the polarity to the motor. The crank that provides the back and forth motion has an eccentric hub so there are two different stroke lengths, short for wiping and longer for parking off the screen. In forward, the forward movement holds the eccentric in the shorter stroke length. Switching off reverses the polarity and the eccentric moves to increase the stroke. 

When the stroke lengthens, it allows the slide to trigger a switch at the end of the longer stroke, this breaks the circuit and the wipers stop off the screen. The knurled knob moves the switch giving some adjustment to the final stop position.

Assuming your wipers have been set to stop on the switch at the edge of your screen, it may be wise to remove your wiper arms when you replace the switch. The park position may be too far of the screen where your arms are set at the moment.

cheers

Martin