Stuck windshield wipers
- Thread starter jfksabal
- Start date
try this
Your wiper motor has a bit too much grease in it and it has hardened up on the "park" contacts in it. Sounds complicated, but it's actually (as far as BMW's go) not TOO hard to fix.
The story is: the wiper motor has contacts in it that make it continue to run, and park. These contacts close on a metal segment on the plastic gear that drives the shaft coming out of the motor (the motor itself is at right angles to this). If the housing had too much grease in it (which was fairly common, at least on my year), or the grease has hardened up.. the contact tend to skip a bit, causing the jerky action. The big hint is that it only occurs in the intermittent mode (which you describe).
TO FIX (Two choices):
1. Go to dealer, sell left arm, buy new motor.
2. Remove motor and clean out grease, regrease.
assuming you may want to tackle #2.. here is how it's done:
1. Remove the motor. I'd disconnect the power connector going to it first (it will try to park otherwise if you accidently rotate it, perhaps taking a finger or two with it). On my 535 - it's behind the cowling for the fresh-air intake for the heater - don't have a clue where for a 3er.. remove the nut (and washer) holding the linkage to the motor, try to prevent it from turning while you remove it. The arm connecting to it is splined, but removes fairly easily (a good tug). Remove nuts/bolts holding motor in vehicle. Walk it to your workbench.
2. Disassemble: The contact you want are behind the light aluminum plate that covers the big gear (this will be fairly obvious).. on mine, the plate was held on with mashed over aluminum studs. Right next to these studs were holes through the plate and corresponding holes into the housing.. sorta looked like these could be tapped to take a few screws for reassembly (CLUE!).
3. Repair it: Drill off the mashed over aluminum heads of the studs (1/4" bit works fine). The cover should remove easily. You'll find lots of nice brownish grease. Clean the contacts (attached to the cover) and the face of the gear where the metal segment is). Regrease lightly with a white lithium grease (at least that's what I used)..very lightly!
While apart - tap the holes in the aluminum housing - I *think* I used 4-40 American (looked about right, and I had the tap and some short 4-40 screws, but it might have been 2-56). Try to keep tap filings out of the housing (grease on the tap helps a lot).
4. Reassemble: Put the cover back like you found it and screw it back together. Reinstall motor in car. Align the motor by starting it once WITHOUT the wiper arm attached and letting it go to the park position. Once it's aligned, refasten the wiper arm in the correct parked position (try NOT to turn the motor while tightening the nut holding the arm).
Your wiper motor has a bit too much grease in it and it has hardened up on the "park" contacts in it. Sounds complicated, but it's actually (as far as BMW's go) not TOO hard to fix.
The story is: the wiper motor has contacts in it that make it continue to run, and park. These contacts close on a metal segment on the plastic gear that drives the shaft coming out of the motor (the motor itself is at right angles to this). If the housing had too much grease in it (which was fairly common, at least on my year), or the grease has hardened up.. the contact tend to skip a bit, causing the jerky action. The big hint is that it only occurs in the intermittent mode (which you describe).
TO FIX (Two choices):
1. Go to dealer, sell left arm, buy new motor.
2. Remove motor and clean out grease, regrease.
assuming you may want to tackle #2.. here is how it's done:
1. Remove the motor. I'd disconnect the power connector going to it first (it will try to park otherwise if you accidently rotate it, perhaps taking a finger or two with it). On my 535 - it's behind the cowling for the fresh-air intake for the heater - don't have a clue where for a 3er.. remove the nut (and washer) holding the linkage to the motor, try to prevent it from turning while you remove it. The arm connecting to it is splined, but removes fairly easily (a good tug). Remove nuts/bolts holding motor in vehicle. Walk it to your workbench.
2. Disassemble: The contact you want are behind the light aluminum plate that covers the big gear (this will be fairly obvious).. on mine, the plate was held on with mashed over aluminum studs. Right next to these studs were holes through the plate and corresponding holes into the housing.. sorta looked like these could be tapped to take a few screws for reassembly (CLUE!).
3. Repair it: Drill off the mashed over aluminum heads of the studs (1/4" bit works fine). The cover should remove easily. You'll find lots of nice brownish grease. Clean the contacts (attached to the cover) and the face of the gear where the metal segment is). Regrease lightly with a white lithium grease (at least that's what I used)..very lightly!
While apart - tap the holes in the aluminum housing - I *think* I used 4-40 American (looked about right, and I had the tap and some short 4-40 screws, but it might have been 2-56). Try to keep tap filings out of the housing (grease on the tap helps a lot).
4. Reassemble: Put the cover back like you found it and screw it back together. Reinstall motor in car. Align the motor by starting it once WITHOUT the wiper arm attached and letting it go to the park position. Once it's aligned, refasten the wiper arm in the correct parked position (try NOT to turn the motor while tightening the nut holding the arm).