240 General: New (to me) 1980 Volvo 244

[Moomoo]

Originally Posted by Othen

This one Dave?



The other end of that is just a shaft with some splines onto which the wiper arm fits, so rotating it through 180 degrees won't change anything apart from moving the splines round half a turn.

This is puzzling me - I keep coming to the conclusion that the motor must be running backwards, but I can't see how that could be possible.

:-(

Alan

Polarity?🤔

[Othen]

Originally Posted by Moomoo

Polarity?🤔

Well, I'd thought of that Andrew, but I can't make sense of it. The 12v DC motor would probably run just as well in reverse if wired that way (internally), but I can't see that the external wiring could produce that error. If you look at the cct diagram:



you will see there is just one -ve return (the brown wire) and two +ve feeds (the black and red) - the red and the black both have to be +ve in order for the motor to run when the washer operates, enter a park stroke when the driver stops pulling the wipers lever and park otherwise. There is also a diode (internal to the motor housing) in each of the red wire (washer pump) circuits.

... I'm still stumped by this one.

:-(

Alan

[Moomoo]

Originally Posted by Othen

Well, I'd thought of that Andrew, but I can't make sense of it. The 12v DC motor would probably run just as well in reverse if wired that way (internally), but I can't see that the external wiring could produce that error. If you look at the cct diagram:



you will see there is just one -ve return (the brown wire) and two +ve feeds (the black and red) - the red and the black both have to be +ve in order for the motor to run when the washer operates, enter a park stroke when the driver stops pulling the wipers lever and park otherwise.

... I'm still stumped by this one.



:-(

Alan

The motor looks like a replacement, not date marked like the other side.

Manufacturing fault? Wrong motor?

[Laird Scooby]

Originally Posted by Othen

This one Dave?



The other end of that is just a shaft with some splines onto which the wiper arm fits, so rotating it through 180 degrees won't change anything apart from moving the splines round half a turn.

This is puzzling me - I keep coming to the conclusion that the motor must be running backwards, but I can't see how that could be possible.

:-(

Alan

Originally Posted by Moomoo

Polarity?🤔

That's the one Alan - are you sure there's nothing between that pinion and the wiper arm except a straight rod?

Andrew raises an interesting concept that i'd certainly overlooked but you've hinted at as well Alan. Try reversing the polarity at the motor itself, if it has been replaced it's possible they got the polarity the wrong way round on the new motor when they fitted it so instead of parking at the bottom, it now parks at the top.
After all, the rack is just a push-pull motion on the pinion so if it's designed to stop at a certain point it will stop there - if it's on the "up-sweep" instead of the "down-sweep" because of reversed polarity this would certainly give the problem you have.

[Othen]

Originally Posted by Laird Scooby

That's the one Alan - are you sure there's nothing between that pinion and the wiper arm except a straight rod?

Andrew raises an interesting concept that i'd certainly overlooked but you've hinted at as well Alan. Try reversing the polarity at the motor itself, if it has been replaced it's possible they got the polarity the wrong way round on the new motor when they fitted it so instead of parking at the bottom, it now parks at the top.
After all, the rack is just a push-pull motion on the pinion so if it's designed to stop at a certain point it will stop there - if it's on the "up-sweep" instead of the "down-sweep" because of reversed polarity this would certainly give the problem you have.

It is certainly just a solid rod between the pinion wheel and the splines Dave:



... like you I thought there might be some sort of trigger attached to it, but it is just a bit of metal.

It is an interesting idea that the motor might have been changed some time in the past. The case has certainly been opened previously (hence the zip ties) but I don't know why. Getting at the +ve and -ve tails for the motor may be a tad difficult as there are other things built into the case, but I'll certainly look at that tomorrow.

It would certainly seem (to me) that just running the motor in the opposite direction would solve the problem.

This is an interesting challenge.

Alan

[Othen]

Originally Posted by Moomoo

The motor looks like a replacement, not date marked like the other side.

Manufacturing fault? Wrong motor?

You may have something there Andrew, the motor has clearly been opened some time in the past, as I told Dave, I don't know why. There are no obvious signs of anything being tampered with inside, but it could have been quite some time ago in the RB's 42 year life.

Good idea.

Alan

[Laird Scooby]

Originally Posted by Othen

Getting at the +ve and -ve tails for the motor may be a tad difficult as there are other things built into the case, but I'll certainly look at that tomorrow.

It would certainly seem (to me) that just running the motor in the opposite direction would solve the problem.

This is an interesting challenge.

Alan

I suspect the previous "rebuilder" didn't check the motor direction before reassembling it Alan and given the "challenge" of swapping the motors wires round, decided to live with it after finding it worked perfectly but gave the RB a permanent quizzical expression.

[Othen]

Originally Posted by Laird Scooby

I suspect the previous "rebuilder" didn't check the motor direction before reassembling it Alan and given the "challenge" of swapping the motors wires round, decided to live with it after finding it worked perfectly but gave the RB a permanent quizzical expression.

Possibly Dave. There are no signs of anything being touched inside the unit - so if it was previously rebuilt it was done very neatly.

I have two other LH units that I believe to be serviceable, but that I think have too long a stroke for the MY 80's headlamps (I think those lights were only used in MY 79 and 80). The only difference appears to be the crank, which is a pretty easy part to swap. What I'll do when I get a mo is link up one of the spare units and see if it rotates in the correct direction, if it does I'll open the case (a bit of a mission) and swap the cranks).

... I have a plan.

:-)

Alan

[Othen]

It took a while, and a bit of experimentation, but I got there in the end.

I knew I had a couple of spare LH units on the 244 spares shelf so I pulled the back off one for a look, after hooking it up to the car's electrics I noticed that:

a. I rotated anti-clockwise (just like the one that was fitted), so my theory about it being wired back to front was disproven.

b. The crank parked 180 degrees apart from the one fitted to the RB previously, so the first movement would always be an upward one (... so it should park at the bottom of the stroke, rather than at the top).

So I might have a solution, the old unit (grey crank) and the spare one (red crank) are shown in this photo, both in their park positions:



... clearly 180 degrees apart. I can only conclude that: as the parking position is set only by the three teeth on the back of the crank, that the motor fitted to the RB must have always had the wrong crank.

Life is never quite as simple as just swapping bits round on a 42 year old motor car, I ended up making up a hybrid unit using the splined shaft plus some of the gear parts from the RB's old one with the motor and electrical controls from the spare part.

The good news is it works:



The RB looks much smarter with a regular smile. Having got it all working properly I'll take it apart again for some lubrication and seal it back up with some silicone.

I suppose the NS wiper motor that came with the RB must have always had the wrong crank fitted. I have no idea how that came about, and why the enclosure had been opened previously (perhaps it was to fit the wrong crank?).

:-)

Alan

[Moomoo]

Oh! That’s a shame, I preferred the smirk!