Wiper motor parking issue

[mach2andy]

Having partially rewired my car, I started to do a few basic checks without the battery fitted and found that there was continuity between the 2 paired green wires in the photo and earth. This sort of worried me a bit as I saw this as a potential dead short. The paired wires came from the load side of fuse 7. I eventually found that both of these wires were wiper related. One to the switch, and one to the motor. This confused me slightly as the wiring diagram has one of these wires to fuse 6 and the other to fuse 7. I realise it makes no difference as fuses 6&7 are bussed together. I disconnected the plug from the motor, and the continuity ceased. So I'm guessing the motor was looking for an earth to park? I had previously changed the motor brushes and tested the motor and all seemed OK. With the motor now in the car, I jury rigged some power to it, and it would not park.
Apart on the bench [yet again] the park switch worked OK when I pressed it, but when operated as it would be by the lobe on the back of the drive wheel, there was no contact being made. You can see in the pics that this lobe has 2 legs that locate it into the back of the drive wheel. I refitted the lobe with 2 tiny plastic washers under the legs, and the park switch now operates as it should do. Back attached to the cars wiring, the motor now operates fine, and parks as it should. BUT I note that the motor does get very warm after operating for several minutes, and I don't know if this is normal or not? And this is without any load, and in an cool environment, not a very hot engine compartment. As for my fix of the park switch, I'm wondering if the plunger on the park switch is worn, and if I should simply replace it? It's the same switch as fitted to a Mini I think?
Any thoughts welcome as ever.
ATB
Andy

[288gto]

Hi Andy,

Sorry I can't help with why the motor is getting hot but can confirm a Mini parking switch fits as I fitted one to mine when I swapped from LHD to RHD and refurbished the wiper motor.

Simon

[johnetype]

Warm, hot are difficult to pin down unless you have one of those infra red remote thermometers.

Certainly these motors do get warm in operation even with no load. As long as no part of the wiper mechanism is partly seized adding extra load, I'd suggest warm is OK. To be definitive you need to measure the no load motor current as per the Lucas Service Manual which I believe is in the Knowledge section. Circa 1.5 Amps iirc.

[mach2andy]

I've checked the current draw of my 15W wiper motor with no load, and sure enough it is much too high. 5 amps as opposed to 1.7amps as it should be, and getting nearly too hot to touch. So at a guess there is low resistance probably caused by deteriorated insulation on the armature windings? I can find a new armature for a 14W motor which looks identical, but not for a 15W. Perhaps someone knows if they are the same? And has anyone had an armature rewound?
Thanks in advance.
Andy

[Gfhug]

Andy, why not try looking at Beaulieu Auto Jumble this weekend? Or Stoneleigh in October. The armature will probably fit other wiper motors and you could compare with items down there. Did I read somewhere the basic unit is similar to one from a Scimitar? Is it the same park switch as a mini and therefore as an E Type?

Interesting info here https://www.s-v-c.co.uk/wiper-systems/

Geoff

[tim wood]

A chap advertises on eBay under the name “tankard03” and specialises in this type of thing. I believe he is also a stall holder at stoneleigh so maybe worth contacting him.


Tim

[mach2andy]

I replaced the park switch which was the same as fitted to a Mini, tested the motor and the park function then worked fine without the need for spacers behind the cam. I sent my wiper motor armature to Robson & Francis who confirmed that it was burnt out. I reassembled the motor with it's rewound armature, and ran it on the bench for quite a while and it now gets only very slightly warm whereas before, you could barely touch it after it had ran for a couple of minutes. And for the umpteenth time it's now back in the car, and hopefully that's where it will remain for evermore!
Andy