Electric wiper motor replacement question
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Lead Driver
Joined: Jul 2011
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From: Rockingham, VA
Electric wiper motor replacement question
My 51 F4 came with an electric wiper motor, and that motor doesn't work. The available 6 volt "replacement" motor kit from LMC Truck does not look like the original assembly, and says it is a direct bolt in replacement for the vacuum motor.
LMC Truck Parts - Page 95
Since I've never seen the vacuum motor assembly, will this kit work with the wiper linkage in my truck?
Or better yet, does anyone know where I could get this original motor repaired?
LMC Truck Parts - Page 95
Since I've never seen the vacuum motor assembly, will this kit work with the wiper linkage in my truck?
Or better yet, does anyone know where I could get this original motor repaired?
Welder User
Joined: Feb 2009
Posts: 5,269
Likes: 50
From: northwest MT
Beware of any retrofit electrical parts.......especially from LMC. I bought their wiper switch.....not even close to usable! Have you tested the motor? I tested mine with some jumper wires and a 6v battery. I got it to move, but it wouldn't work right until I got a good original switch hooked up. They also have 2 speeds.......
I would look around your area for an "electric motor rebuilder" or similar....
I would look around your area for an "electric motor rebuilder" or similar....
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Lead Driver
Joined: Jul 2011
Posts: 6,599
Likes: 34
From: Rockingham, VA
Yeah, I tested it. I found a couple of motor repair shops nearby. I'll check with them to see if they can work on it.
Do you happen to have a wiring diagram that shows that circuit of 3 wires off the switch? It's not on the diagram I have. I'd like to be sure I tested it correctly.
Do you happen to have a wiring diagram that shows that circuit of 3 wires off the switch? It's not on the diagram I have. I'd like to be sure I tested it correctly.
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Lead Driver
Joined: Jul 2011
Posts: 6,599
Likes: 34
From: Rockingham, VA
I did more research on this site, and finally figured, hey, this is just a motor with different taps for different speeds. So I tested it first with an ohmeter to see which was highest and lowest resistance (for coil size). And because someone on this site actually mentioned that the motor gets its ground through the frame mount, I no longer needed a wiring diagram to test the motor correctly.
I had to hit it with 12 volts to get it started. My first thought was that it's a 12 volt motor... but that can't be right because it's stock. When I hit it with 6 volts again, it ran... both low speed and high speed.
I opened the two gearboxes and cleaned the 60 year old caked grease. I replaced it with some high tech grease I use on rocket motor linings. Now the motor purrs like a well greased kitten... whatever that is.
I decided that since I was now keeping it, I should try to clean it up a bit.
Here's a pic after I removed it from the truck.
And after I checked it and cleaned it up a bit.
Now I need to check the wiring and the switch. Of course, it may work, since the 12 volt shock was needed to get it started.
I had to hit it with 12 volts to get it started. My first thought was that it's a 12 volt motor... but that can't be right because it's stock. When I hit it with 6 volts again, it ran... both low speed and high speed.
I opened the two gearboxes and cleaned the 60 year old caked grease. I replaced it with some high tech grease I use on rocket motor linings. Now the motor purrs like a well greased kitten... whatever that is.
I decided that since I was now keeping it, I should try to clean it up a bit.
Here's a pic after I removed it from the truck.
And after I checked it and cleaned it up a bit.
Now I need to check the wiring and the switch. Of course, it may work, since the 12 volt shock was needed to get it started.
Lead Driver
Joined: Dec 2004
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From: San Jose, CA
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Lead Driver
Joined: Jul 2011
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From: Rockingham, VA
OK, but first let's see if I get the wipers working again. 
By the way, have I mentioned lately that FTE ROCKS!
By the way, have I mentioned lately that FTE ROCKS!
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Ford Parts Specialist
Joined: Nov 2006
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From: Simi Valley, CA
No Ford Dealer or obsolete parts vendor has any.
-----------------------------------------------
8C-17470 .. Wiper Switch-Use with A8TZ-17508-A wiper motor / Obsolete
BOWMAN SALES & SERVICE in Bowman ND has ONE = 701-523-3257.
ANTIQUE AUTO SUPPLY in Arlington TX has TWO = 817-275-2381.
WESLEY OBSOLETE PARTS in Liberty KY has THREE = 606-787-5293.
Welder User
Joined: Feb 2009
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From: northwest MT
Fleet Owner
Joined: Jul 2004
Posts: 27,296
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From: NM
The electric and vacuum wiper systems use completely different linkages.
There are all kinds of systems available to replace either the vacuum or stock electrical systems. A lot of people have fabricated adaptations of Cavalier, Jeep and other modern systems. It isn't easy to get the right sweep and still get it into place. 48-50's are really tough unless you hack the underdash braces. I'm going to make a system using parts from these guys this winter: Windshield Wiper Blades and Systems | DC Electric Motors | Wiper Motor Assembly | AM Equipment
Here is the wiring diagram.
There are all kinds of systems available to replace either the vacuum or stock electrical systems. A lot of people have fabricated adaptations of Cavalier, Jeep and other modern systems. It isn't easy to get the right sweep and still get it into place. 48-50's are really tough unless you hack the underdash braces. I'm going to make a system using parts from these guys this winter: Windshield Wiper Blades and Systems | DC Electric Motors | Wiper Motor Assembly | AM Equipment
Here is the wiring diagram.
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Lead Driver
Joined: Jul 2011
Posts: 6,599
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From: Rockingham, VA
Thanks for the diagram. I worked on it earlier this evening and checked out the switch, which works. Then I checked for voltage on the wires at the motor end, and got none. So I crawled under the dash to trace the wires from the switch, and discovered the power lead had been connected to a ground lug under the speedo. 
Same place a PO grounded the horn button they mounted to the side of the column.
I moved the power wire to the ACC side of the ignition switch, plugged the old wires into the motor, rigged a ground wire from the motor body to a frame ground, turned on the power, moved the switch, and got low speed and high speed.
What I don't understand is why it sometimes won't stop when I return the wiper switch to OFF. And sometimes, it won't start when I turn the wiper switch ON. But I'll figure it out.
Same place a PO grounded the horn button they mounted to the side of the column.I moved the power wire to the ACC side of the ignition switch, plugged the old wires into the motor, rigged a ground wire from the motor body to a frame ground, turned on the power, moved the switch, and got low speed and high speed.
What I don't understand is why it sometimes won't stop when I return the wiper switch to OFF. And sometimes, it won't start when I turn the wiper switch ON. But I'll figure it out.
More Turbo
Joined: Nov 2007
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From: Melbourne Australia
Fleet Owner
Joined: Jul 2004
Posts: 27,296
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From: NM
Joe, check the grease inside the two gearboxes. On the one of mine I opened, all the grease had turned stiff and was around, but not touching, the gears. In other words there was a lot of grease but it wasn't doing any good.
As far as not stopping, there is a little button in the motor switch (on the motor) that rides a cam. That is the parking switch. Mine was really worn and didn't really break the circuit.
As far as not stopping, there is a little button in the motor switch (on the motor) that rides a cam. That is the parking switch. Mine was really worn and didn't really break the circuit.