Late 30s - Early 40s Fan Motor Maintenance

[Daves1940Buick56S]

There was a request for lube recommendations on one of these a while back, and rather than hijack that I thought I would make a separate thread for bookmark purposes. This is a quick set of instructions for bringing one of these back to life. This is for a heater fan, the defroster motors are similar but smaller.

 

1. Pull off fan blade (should be a setscrew) and remove fan motor from shroud.

2. Remove the 2 nuts and washers on the front (shaft) side.

3. Ease the front shell off by sliding over the shaft. If lots of corrosion is present on the shaft, lightly sand and put a bit of light oil on to facilitate removal.

4. Remove the 2 small nuts that are up against the phenolic brush board.

5. Remove the 2 screws and carefully remove the 2 brass spacers.

6. Remove the field coil/brush and rotor together from the back shell, feeding the wire through as necessary.

7. Using toothpicks or similar, work the brushes back and remove rotor out the rear of the field assy.

8. Remove all washers from the rotor. Clean the rotor/commutator and field assy with CRC QD cleaner or equivalent

9. Examine the commutator. The QD cleaner may be sufficient. If not, chuck the rotor into a drill and lightly sand with 1000 grit sandpaper (not emery).

10. Using a fine needle, carefully clean out the small gaps between the commutator segments. Go over with QD one more time.

11. Examine the brushes. The should easily move in the brass slots with spring action evident. If they are gummed up there should be enough brush lead wire to carefully remove from the slots along with the springs. Clean out the slots with a Q-tip soaked in QD. Reassemble and check for proper operation. Note the brush position on the photo below. This is about right with relaxed springs.

12. Clean up the remainder of the parts with Brakleen or similar.

13. Soak the felts in the bushings in the front and back shells with light machine oil.

14. Reassemble in reverse order, making sure that the brushes don't get dinged up when inserting the rotor into the field assy.

 

See pix below

Entire motor assy

 

Rotor and washers, commutator on right

 

Closeup of brushes on phenolic

[buick looks fine for 39]

 I had the inquiry about heater motor cleaning and lubrication and your post was very helpful.

 

Thanks for your reply, Leif "Buick looks fine for 39"