Windshield wiper motor after 16 years and 300,000+ miles. (1 Viewer)

[Kernal]

Thought I'd post up what I found when I pulled the original windshield wiper motor. It sometimes would run slower and was making a sorta growling noise which was more noticeable after I had removed the wiper arms. With the motor apart I found that the magnet on the bottom side of the case had come loose, probably due to rusting of that side of the case. The case was not designed with an O-ring, it might originally had a swipe of some factory sealant but it looks like that dried up long ago. The brushes after all these years still have some useful length remaining.

The photos show how the steel of the armature had been grinding on the magnet which was (magnetically) stuck right up to and riding on the armature, surprising that the wipers worked as well as they did. The bearing for the armature shaft was a bit rough feeling when I spun it by hand, dry for sure, and it's an uncommon size; 9.8mm ID x 20mm OD x 6mm high/wide. The number stamped into the shield of that NSK bearing is B9Z-32AZ. The armature has a captured ball bearing on one end of the shaft that's lubed by oil soaked into a packing at the pointy end of the motor case. After 16 years that ball bearing and the packing were still wet with oil, would be interesting to know what type/brand oil was used originally. Plan is to install a lower mileage wiper motor I picked up awhile back and rebuild this one eventually.

 

[Kernal]

A few more photos; first shows the loose magnet back in position and the oiled felt packing where the ball bearing-tipped shaft rides. I used a 20W turbine oil I picked up from Ace_Hardware. Last photo shows the three brushes and their springs; the springs will fall out once unsprung from the brush holders if the assembly is tipped over.

 

[Kernal]

A few more. I'm thinking that the case could be sealed better where it mates to the housing and maybe add a rubber vent to the open vent hole like what's used in starters to vent the case. The large white worm gear does not just fall out of the housing, it appears to be tightly held onto the shaft that connects the motor to the linkage. The rust was mostly on the inside lower side of the case, maybe from condensation or water somehow trickling in from where the steel case mates to the aluminum housing?? You can see how the rust got behind the magnet which was on that lower side; there's still a faint white line from the original epoxy.

 

[gtfour43]

Very interesting. Mine has been slooow lately too. I'll need this done someday as well. Thanks for documenting this.

 

[Kernal]

Here's a few photos showing the windshield wiper motor's armature shaft bearing. This used bearing has a slight notchiness to it but should be reuseable. I'll replace it if I can find a new one but NSK said they don't have any in stock in the US. So I popped the plastic (polyamide) seal off to clean and regrease this one, the photos show the seal is also the cage for the bearings. After cleaning the bearing out using CRC Electronics cleaner I packed the bearing (about 1/2 full) with grease meant for this type bearing. When putting the seal/cage back on I first lined up the bearings equally spaced around the race so the balls could be popped back into the cage as I pressed it in; took a few tries working the seal/cage edge down but it eventually popped back into place.

Edit: the photos below show the bearing after it was cleaned and regreased and are staged to show how it comes apart and fits together. The first photo shows the cleaned and repacked bearing.

 

[Sam Stewart]

Just think, if it was a domestic product, you'd be on your third motor by now! I'd say that's pretty darn good for that amount of time and mileage.

 

[Michael Hanson]

Seal prob. failed, mine still going strong. MIke

 

[Kernal]

Mike: The photos above of the bearing on the shaft where taken after I cleaned out the old grease and are in reverse order; the first photo is after it had been cleaned, greased and popped back together.

Lowe: I agree, the wipers still worked most of the time normally even with a loose magnet being ground down by the armature. The main clue was that motor was growling some when in operation. This was more obvious once I had removed the wiper arms and then ran the motor without the competing noise from the blades swiping across the windshield. It wasn't clear that the noise and occasional slow wiper motion was due to the motor alone so I pulled the linkage also.

 

[Kernal]

Update; got the wiper motor back together and it worked, but it still made a growling noise; not sure why as the worm gear was not obviously worn nor was anything else?? Maybe the viscosity of the grease is too light (Molykote 33 Light)??.

Made an error on reassembly; before pulling the bracket arm off the shaft I had made score marks on the bracket and the tip of the shaft where the nut is. When I put it back together I went by memory (instead of refering back to the photos I took) and got it 180 degrees off. After connecting the linkage and motor back up then attached the wiper arms the arms would clock too low and bang into the cowl. I figured it out by painting some white dots on the tips of the splined linkage shafts (where the arms attach) and saw that 180 degrees off at the motor equated to 45 degrees of wiper arc at the wiper arms. So don't make that mistake if you ever tear your wiper motor apart.

Another tip: when I first pulled the wiper motor off the linkage the chromed ball popped out of the nylon bushing on the end of the linkage without much problem just by levering the motor away from the linkage. The next time I went to do this the motor would not come loose and I began to bend the linkage.

So as I couldn't find any ready made tool that would work I made a tool out of a small 8" flat bar type nail puller that I picked up at Home_Depot for about $4. Using a cutting wheel I cut about 7/10th of an inch out of the middle of one end leaving two "fork tines" about one inch long each which straddled the width of the chrome ball (see photos below for reference). I slid that tool between the chrome ball and the booted end of the linkage that has the nylon bushing inside and pried slighty to pop the ball out of the bushing; easy. Screwdrivers, wrenches, pliers, upholstery tools, you name it, nothing else worked.