Wiper motor maintenance/repair
Posted: Sat Dec 17, 2011 12:03 am
Here in sunny California winter really does eventually arrive. I had to find a wiper motor for my new moggy (as she came without one) and made a find on EBay. New ones go for something over $300 US.
Once in my hands, I discovered that the motor wouldn't run (which was OK, as seller made no warranty and price was $30) so I tore it down.
Here's the problem: It's hot under the bonnet, and the good folks at Lucas packed the gear box of the wiper drive with grease some many decades ago. The heat tends to drive off the volatiles in the grease, making it thicker over time. Mine was so thick that it cut like a chocolate bar on a cool day and was about the same color -- although it smelled like something that had rolled in on the tide and lay on the beach for several days.
The solution was to disassemble the whole thing -- providing access to the many bearing surfaces -- clean thoroughly and re-grease. It now runs happily and with real authority. The old grease was not only thickened, it was actually sticky, having a sort of anti-lubricant quality.
So, I'm suggesting that it might be a good idea to periodically pull the top of the gear casing (easily done on the car, just 4 screws) and check the grease. Adding something of lower viscosity -- like plain old 30 weight -- and running the motor while you watch it work in and mix with the yuck. Observe the wonders of converting roundy-round motion to reciprocating. You'll never get to all the bearings this way but you can probably improve things. The full tear down, cleaning and re-grease is pretty simple and quick, but does require removing from the car. Don't forget to clean and grease the cable while you've got it out.
And, you might as well replace the brushes if they need it. Pop the end cap off the motor (two long screws that mount the motor to the gear case housing) and the brush assembly while be right there in front of you. Brushes are easy to get in and out because the carriers are on a spring. For those who may not know, you needn't hunt all over for Lucas brushes -- just drop by the local hardware and get any carbon brush that's bigger than what you need. You can very easily re-size the brush by working it over some sandpaper taped to the bench top. The Lucas brushes have no embedded wires either, so it's just that much easier!
Once in my hands, I discovered that the motor wouldn't run (which was OK, as seller made no warranty and price was $30) so I tore it down.
Here's the problem: It's hot under the bonnet, and the good folks at Lucas packed the gear box of the wiper drive with grease some many decades ago. The heat tends to drive off the volatiles in the grease, making it thicker over time. Mine was so thick that it cut like a chocolate bar on a cool day and was about the same color -- although it smelled like something that had rolled in on the tide and lay on the beach for several days.
The solution was to disassemble the whole thing -- providing access to the many bearing surfaces -- clean thoroughly and re-grease. It now runs happily and with real authority. The old grease was not only thickened, it was actually sticky, having a sort of anti-lubricant quality.
So, I'm suggesting that it might be a good idea to periodically pull the top of the gear casing (easily done on the car, just 4 screws) and check the grease. Adding something of lower viscosity -- like plain old 30 weight -- and running the motor while you watch it work in and mix with the yuck. Observe the wonders of converting roundy-round motion to reciprocating. You'll never get to all the bearings this way but you can probably improve things. The full tear down, cleaning and re-grease is pretty simple and quick, but does require removing from the car. Don't forget to clean and grease the cable while you've got it out.
And, you might as well replace the brushes if they need it. Pop the end cap off the motor (two long screws that mount the motor to the gear case housing) and the brush assembly while be right there in front of you. Brushes are easy to get in and out because the carriers are on a spring. For those who may not know, you needn't hunt all over for Lucas brushes -- just drop by the local hardware and get any carbon brush that's bigger than what you need. You can very easily re-size the brush by working it over some sandpaper taped to the bench top. The Lucas brushes have no embedded wires either, so it's just that much easier!