I have 4 motors. I decided to convert these to self parking.
Reason is I was interested in adding a intermittent circuit and they all work only on self parking wiper motors.
These are single speed. Dual speed adds another electrical commutator brush.
Describes how wiper motors work.
The shafts were tight due to rust internally built up. Tight enough some I could not turn by hand.
I tried soaking in oil but was so slow, so turned up the heat and very quickly the rust came off and they spin freely now. Probably oil got to 300 to 400 degrees. I used a 0-20w full synth oil.
Took about 30 minutes to clean out the internal rust.
When these went into hot oil, air bubbled out the end of the shafts. Then picking up with pliers and spinning the shafts, lots of rusty froth came out the ends. kept soaking and spinning the shafts till I saw no more rusty froth, then let them soak. I cooled down and reheated twice. Now when cool they spin smoothly and easily.
Those have a steel shaft and a brass housing, supposedly a rubber ring at the top keeps out water.
Second picture shows the parking feature I am adding. I will put a cam on the nylon gear to push open the relay contacts.
The cam idea I have is tap a #4-40 hole into the plastic gear. then put a 4-40 machine screw with a thin plastic bushing cut from a plastic tube. So when the gear comes around it will push open the contacts shutting off the motor ( creates the self parking). To align when it shuts off, you have to position the gear to where it moves the crank to the furthest it can go, and that is where the cam needs to be
The contact arms I obtained from an old manual dishwasher Frigidaire timer.
I am sure few people would do this. But if you have tight shafts in your wiper motors, you can dissolve out the rust with hot synthetic oil.
The picture of the wiper motor housing shows one with contact points added and one as was OEM.
So these shafts are now sitting in clean 0w-20 oil. I think this particular hot engine oil must be reacting chemically with rust dissolving it away. I am surprised how well this worked out.