DR3A wiper motor or hot plate in my car!

[Andmurph]

Good evening,

I spent much of today working on our newly acquired pickup. After sorting out the self cancelling indicators it had a full service.
Whilst adjusting the choke cable I burnt my arm on the wiper motor which had become very hot even though the wipers were switched off. Are these prone to fail? I disconnected the three wires for now and will investigate further another day. It took almost an hour to cool to touch.

I see reconditioned units are available, can anyone recommend a shop that does the rewinding? I’d heartily recommend V&C Engineering for damper reconditioning and Classic Card LEDs but I don’t know a workshop for wiper motors.

Many thanks


Andrew

[svenedin]

The Lucas DR3A can become very hot when the grease inside has thickened and become hard and the motor is struggling to operate the wipers. Are you sure the wipers were actually switched off?

The three connections to the motor are earth, switched live and permanent live. The permanent live is needed so that the wipers will self-park when switched off. If the loom is original, the permanent live has a special connector so that it cannot be misconnected to the switched live socket on the motor.

It may be that there is an internal short in the windings as you suspect but they should not be staying energised if the switch is off. Another possibility is that there is a problem with the internal self-parking contact (be careful with this contact as they are no longer available).

Robson and Francis Rewinds Ltd in Streatham, London will rewind almost any motor from a 1920's Rolls Royce starter motor to a motor from a tower crane. They have done excellent work for me and a visit to their workshop is fascinating.

If you are keen on originality, the wiper motors are date stamped so it would be best to repair what you have if it is original to the car. Unfortunately, even in perfect condition, the single speed DR3A wipers are quite slow. Some owners fit a later 2 speed motor. I have found that the DR3A is adequate even in torrential rain if Rain-X is used on the windscreen.

Stephen

[Andmurph]

Thanks Stephen!

On Tuesday I opened up the motor, after a good look around the internet to see what spare parts I could find. I didn’t buy parts but as you say the park switch contact is not available anywhere.
The motor brushes were in serviceable condition so I opened the top and cleaned out the gear box. The old grease was incredibly sticky and took a lot of cleaning but the gear wheel and drive are in very good condition so I removed them and tested the wiper switch wiring and checked to motor ran well. I then reassembled and packed with some ACF corrosion block blue grease. Reconnected the cleaned and re greased rack and set the park switch as per the instructions in the Morris Minor Workshop Manual section N.36.
The wipers now function as they should without the motor getting hot. Very lucky given it was smoking and burnt my arm last week.

Now it is working properly I will do some cosmetic work to clean and restore the case. It is probably not original to the ‘71 pickup as it’s dated 2 66. It would be a shame not to preserve it though while it works. I’ll keep Robson and Francis in my notes just in case I need them in future.

[svenedin]

Well done. Good job!

Yes the self parking contact was available from Holden but when they moved premises they lost the box. Probably the last NOS parts in the world but no doubt they still exist in the warehouse somewhere......

Old solidified grease is the usual trouble. If the motor still struggles then the grease has also hardened inside the Bundy tubes that the wiper rack runs in. Sometimes a wiper wheel box can seize too. Don't fiddle with these if you do not need to as it is an awful job.

I do notice that the wiper brushes probably do not have much service life left. If you change them it would be a good idea to clean up the commutator as well.

I would also suggest cleaning up the spade terminals as corrosion causes high resistance which leads to heat.

I agree keep the motor if it is working. It may have been an exchange unit years ago if it is actually earlier than the van.

All the Best,


Stephen