mthomas4147
New Member
- Joined
- April 21, 2012
- Messages
- 8
- Reaction score
- 0
- Year, Model & Trim Level
- 1991 Explorer XLT
A really bad humming / buzzing noise from the airbox prompted R&R of the blower motor assembly. Looking over the squirrel cage it was obvious the plastic fins had broken loose and obviously ended up rubbing against the inside housing, creating the racket. Installed the new motor assembly and all was well upon testing.
A few days later and the buzzing was back - upon pulling the motor and inspecting the squirrel cage it was apparent that it was rubbing against something inside the housing box -
looking inside the box I noticed that that there was a buildup of plastic inside the circular recess that the cage runs in - the original cage must have been rubbing for some time and had deposited 1/16" thick plastic coat inside the recess - the new cage must have just fit inside the debris field, and when running in low speed tracked ok without interference - but then a long run on high speed forced the cage to expand outward colliding with the junk leftover from the original motor assy.
I fixed the cage fins with epoxy, and ensured that the cage ran true with no vibration. I then scraped out all the debris from the housing recess, and dressed it with sandpaper. To ensure that there is no expansion of the squirrel cage, I made a belt out of small dimension cable ties linked together to get the length required to capture the circumference of the cage and it arrested any expansion due to centrifugal force. The plastic making up these cages is similar to that used in making milk cartons - pretty soft stuff. Running the motor assembly before installing it in the housing, you can really see how much it expands when running it at full speed vs low speed.
So, check inside the housing for plastic bits, and a smooth recessed surface for the cage to run in, and things should work out for the next guy - just sayin....
A few days later and the buzzing was back - upon pulling the motor and inspecting the squirrel cage it was apparent that it was rubbing against something inside the housing box -
looking inside the box I noticed that that there was a buildup of plastic inside the circular recess that the cage runs in - the original cage must have been rubbing for some time and had deposited 1/16" thick plastic coat inside the recess - the new cage must have just fit inside the debris field, and when running in low speed tracked ok without interference - but then a long run on high speed forced the cage to expand outward colliding with the junk leftover from the original motor assy.
I fixed the cage fins with epoxy, and ensured that the cage ran true with no vibration. I then scraped out all the debris from the housing recess, and dressed it with sandpaper. To ensure that there is no expansion of the squirrel cage, I made a belt out of small dimension cable ties linked together to get the length required to capture the circumference of the cage and it arrested any expansion due to centrifugal force. The plastic making up these cages is similar to that used in making milk cartons - pretty soft stuff. Running the motor assembly before installing it in the housing, you can really see how much it expands when running it at full speed vs low speed.
So, check inside the housing for plastic bits, and a smooth recessed surface for the cage to run in, and things should work out for the next guy - just sayin....
