Most helpful positive review
7 of 7 people found the following review helpful
Consider cleaning the bearings, rather than buying a new motor..
on November 17, 2012
Broan Attic Fan (340, 343, 350, 353) Replacement Motor # 97009316
Having removed our 9-year old Broan attic fan for a remodeling project, it was obvious that the fan blade didn't turn as easily as when it was new. However, rather than buy a replacement motor, I simply cleaned the bearings on the old one. Some notes:
- Our fan's motor has a 3-prong cord plugged into a dedicated receptacle next to it, which simplified removing the unit. We have 3 attic fans and I always install a short heavy-duty extension cord on the fan and mount a receptacle nearby - to simplify maintenance.
- Removed the fan blade and unloosened two of the three bolts that held the motor clamp tight.
- Removed the two screws that held the thermostat on the fan frame and removed the motor & thermostat together.
- Removed the nuts and bolts that hold the 2 halves of the motor housing together.
- Separated the motor casing ends - the armature then comes out easily, along with the front motor casing.
- Since the long shaft was rusted beyond where the fan attaches, I used a bench mounted wire wheel to de-rust it. A rusted shaft won't slide out of the front bearing.
- Slid the front motor casing, which contains the front sleeve bearing, off the armature shaft.
- Thoroughly cleaned the gunk on the shaft at the bearing locations using a paper towel with paint thinner, along with steel wool. The front shaft on my motor was coated with what looked like tar, which can happen to oil that's repeatedly over-heated. This "tar" retards motor RPM's, making the fan less efficient. Eventually, if it slows the motor enough, a tar build-up could result in a burned out motor. The rear bearing area was much cleaner.
- Cleaned the inside of the sleeve bearings.
- Oiled the sleeve bearings on their insides and the shaft where it touches the bearings, with synthetic motor oil, since it's slicker and has a higher operating temperature range, than refined oil.
- Reassembled the unit - mounting the motor so that the shaft was at a right angle to the fan housing. The fan turned much easier by hand than it did before. Electrified the fan for a test run before re-installation, to ensure proper operation.
I've disassembled many motors and this is the first one with STEEL versus bronze, sleeve bearings. Broan probably saves two bucks per motor by using the cheaper steel sleeve bearings, and the end result is a motor won't last as long as it would if bronze bearings were used. (I.e., the bearings gum up, at which point, most people would replace the motor.) The steel sleeve bearings are so hard that the motor shaft showed some wear at the front bearing area - this is something I haven't seen with bronze bearings, since bronze is not hard enough to wear down a steel shaft.
This "repair" costs nothing and took about 30 minutes. There's no reason it couldn't be repeated as needed.
One star off for Broan using cheaper bearings.