coyotegray
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Does anyone know if a rebuild kit is available for wiper motors..?
Thanks,
Andy..
-
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Windshield Wiper Motor Rebuild
- Thread starter coyotegray
- Start date
Does anyone know if a rebuild kit is available for wiper motors..?
Thanks,
Andy..
oddshot
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- Jasper, Georgia
Every question deserves an answer.
So: How do you rebuilt or service the air powered wiper motor found in the M35A2?
The only tools required are whatever you need to remove the motors from the truck PLUS a Phillips screwdriver, an ice pick (or similar) and a pair of pliers. I’m not certain what the o-rings are made of, so I recommend a non-petroleum grease of some sort … I use silicone grease.
Remove the motors from the truck … clean them with soapy water and a stiff brush.
On the outside of the motor you will find a rectangular cover. Carefully pry this cover off the motor. Inside you will see a Phillips screw. Remove this screw. Pull the wiper arm shaft out of the motor; shake the plastic pinion gear out of the motor.
Remove the 7 screws from the cover at the end of the motor, lift off the cover, being careful not to tear the rubber gasket. Using your pliers, pull the piston out of the body of the motor.
Clean up the bore of the motor and the piston with clean paper towels, being careful not to put any scratches in the bore.
Inspect the o-rings and the rubber end gaskets. BTW … these gaskets are not really a “diaphragm” as some have suggested. These motors work by compressed air pushing the piston to one end of the cylinder … where it blocks off one pressure hole and reveals another pressure hole at the other end of the bore. The air pressure from this hole pushes the piston back in the other direction. The only thing I can see that can jam them up (at least the plastic bodied ones) is dried grease, de-graded o-rings or a leak in the gaskets or air feed lines. The piston is cut with a gear like the “rack” of a rack and pinion steering mechanism.
If the gaskets and o-rings are good … good go ahead and re-use them. Lube the o-rings with the silicone grease and re assemble in reverse order.
NOTE: If you examine the piston, at its middle you will see a bump sticking out from its side. You can see this in the photo below. This bump is used to provide a visual means of centering the piston in the bore. When you assemble the piston back into the bore, center that bump where the wiper arm shaft pushes through the motor. Then drop the pinion gear into the rectangular hole, and push the wiper arm shaft through, and install the retaining screw. If you assembled everything correctly, you will have equal travel in both directions when you push and pull the piston.
When you screw the end cover on, tighten the screws in a star-shaped pattern to draw the cover down flat and square to the motor body. Don’t use a lot of force tightening these screws; you can damage the gasket if you do.
When you do the first one … the whole job shouldn’t take but about 15 minutes. After that, it all depends on how many beers you’ve had.
As for rebuild kits … they might be out there, but I haven’t seen any on the market. Maybe somebody knows where you can get them.
The 2 O-rings measure:
ID: 1 9/16’ ; thickness diameter .140” or (about ) 9/64” (my old eyes…)
This should give a OD of 1 7/8”... but my old eyes ain't what they used to be.
If you *really* had to … you could I suspect you could cut these gaskets out of rubber (like an inner tube), cork, or heavy gasket paper. I would use a small paper or leather working punch … or even a piece of brass tubing … to cut the holes for air passages and screws.
Bench check them with compressed air before installing them in your truck.
oddshot
So: How do you rebuilt or service the air powered wiper motor found in the M35A2?
The only tools required are whatever you need to remove the motors from the truck PLUS a Phillips screwdriver, an ice pick (or similar) and a pair of pliers. I’m not certain what the o-rings are made of, so I recommend a non-petroleum grease of some sort … I use silicone grease.
Remove the motors from the truck … clean them with soapy water and a stiff brush.
On the outside of the motor you will find a rectangular cover. Carefully pry this cover off the motor. Inside you will see a Phillips screw. Remove this screw. Pull the wiper arm shaft out of the motor; shake the plastic pinion gear out of the motor.
Remove the 7 screws from the cover at the end of the motor, lift off the cover, being careful not to tear the rubber gasket. Using your pliers, pull the piston out of the body of the motor.
Clean up the bore of the motor and the piston with clean paper towels, being careful not to put any scratches in the bore.
Inspect the o-rings and the rubber end gaskets. BTW … these gaskets are not really a “diaphragm” as some have suggested. These motors work by compressed air pushing the piston to one end of the cylinder … where it blocks off one pressure hole and reveals another pressure hole at the other end of the bore. The air pressure from this hole pushes the piston back in the other direction. The only thing I can see that can jam them up (at least the plastic bodied ones) is dried grease, de-graded o-rings or a leak in the gaskets or air feed lines. The piston is cut with a gear like the “rack” of a rack and pinion steering mechanism.
If the gaskets and o-rings are good … good go ahead and re-use them. Lube the o-rings with the silicone grease and re assemble in reverse order.
NOTE: If you examine the piston, at its middle you will see a bump sticking out from its side. You can see this in the photo below. This bump is used to provide a visual means of centering the piston in the bore. When you assemble the piston back into the bore, center that bump where the wiper arm shaft pushes through the motor. Then drop the pinion gear into the rectangular hole, and push the wiper arm shaft through, and install the retaining screw. If you assembled everything correctly, you will have equal travel in both directions when you push and pull the piston.
When you screw the end cover on, tighten the screws in a star-shaped pattern to draw the cover down flat and square to the motor body. Don’t use a lot of force tightening these screws; you can damage the gasket if you do.
When you do the first one … the whole job shouldn’t take but about 15 minutes. After that, it all depends on how many beers you’ve had.
As for rebuild kits … they might be out there, but I haven’t seen any on the market. Maybe somebody knows where you can get them.
The 2 O-rings measure:
ID: 1 9/16’ ; thickness diameter .140” or (about ) 9/64” (my old eyes…)
This should give a OD of 1 7/8”... but my old eyes ain't what they used to be.
If you *really* had to … you could I suspect you could cut these gaskets out of rubber (like an inner tube), cork, or heavy gasket paper. I would use a small paper or leather working punch … or even a piece of brass tubing … to cut the holes for air passages and screws.
Bench check them with compressed air before installing them in your truck.
oddshot
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If you will go back to 8/12 and find a thread "Wiper Motor Reset Button" you will also find pics of the end disassembled. These pics show the air passage ways in the end cap. If your motor isn't working either the o rings are worn/sticking, just replace them, or junk has gotten into the air ways plugging them up. I have a very small air nozzle I used to blow air backwards thru the passage ways. You could also use carb cleaner etc as long as it doesn't hurt the plastic. There is an inaccessible valve in this endcap that diverts the air from one side to another. If its stuck/not working there isn't much you can do to fix it. ALSO, make SURE the reset button is out. If it's stuck in blow air into the discharge tube on top and force it back out. The motor won't work if the button is pushed in.
