Mercedes-Benz Forum banner

Windshield Wiper crash & "repair"

49K views 41 replies 12 participants last post by  invisik 
#1 · (Edited)
Today the driver-side windshield wiper arm "crashed", it got stuk at the side of the window.
I was able to push the wiper arm in, and then it came back down to the rest position. I didn't use the wipers the rest of the day.

When I dissassembled the complete wiper arm assembly, I discovered that a small plastic wheel was broken inside the housing of the driver-side arm (the arm that wipes a funny pattern over the windshield, by going in and out)

A used replacement wiper assembly would cost be about $300, a new one about $1000, so I decided to try to "Repair" it.

I am sorry, but I did not make any pictures, I hope the next description about how I fixed it, will be clear enough, it is pretty straight forward.

- be carefull not to damage the windshield!
- remove the large plastic cover of the interiour filter (6 nuts) to make some space
- Remove the plastic cover that is on the driver-side wiper arm, closest to the wiper.
- unscrew the inbus and gently pull off the arm with the wiper
- now lift up the large plastic cover of the arm and slide it of towards where the wiper was.
- remove the nut from the passenger side wiper arm and remove the arm
- remove all the plastic covers at the bottom of the windshield, remove the plastic center pins and then pull out the outer plastic things, then the covers can be removed.
- unplug the connector of the windshield wiper motor
- now remove all the nuts (7) that keep the wiper assembly in place
- gently remove the complete assembly (slide it a bit towards the driverside)

- now put the assembly on the floor or a table for easy access
- now remove the big center nut at the driver-side arm, it is at the back-side of the assembly
- remove the small metal clip that is around the axis, to fix it in place
- pull/push out the remaining part of the driver-side wiper arm, use a hammer to push it out to the front of the assembly
inside it, you will see a plastic gear.
- In my case, this gear was broken, causing the wiper arm not to go in at the moment it should
- remove the broken plastic gear

- now re-assemble in reverse order
- fix the arm in the most inner position, so it will not touch anything when wiping, I used some towingstraps.

result is that the area being wiped is a little bit smaller, but still good enough, an you saved a few hundred dollars.

here is a picture of the broken gear:
 

Attachments

See less See more
1
#29 ·
I also changed the plastic wheel.
Assuming that wiper arm is in fully extracted position when the little wheel is in middle of travel (that is the only possible remounting postion as shown above) is WRONG! When wiper arm is in middle of one cycle the arm should have peaked and arm is in retracting mode.

When I reassembled my wiper mechanism I assumed that arm should be fully extracted in 45 degree position. This is wrong and will make your arm touch the roof (as I could notice when the mechanism was remounted). I had to readjust the arm position - and I was lucky at first try.

To understand the motion of arm forget all about the degrees. only thing that should be considered is that when arm is in fully upright position it should not touch the roof and when going down it should not touch A-pillar. When arm is in rest pos it is slightly extracted - then fully retracted - fully extracted - fully
retracted - slightly extracted before going back down. After getting my arm right I measured that blank steel on arm is visible appr. 3 cm. in rest pos.

Good luck

JH
 
#30 · (Edited)
Hmmmm, I have to admit, my arm is very close to the roof, but not touching it, its only a few mm away, I thought this was the way it should be.

when sliding the gear in, there is a little room for adjustment left and right, maybe I was lucky.

So you are saying the arm must just have passed its maximum length when sliding the gear into position, so it is in retracting mode ?

I have changed the description a bit, to correct it, please check if you agree now, so other people can do it right the first time.
 
#31 · (Edited)
Yes, the arm should be slightly retracted when it is in middle of the cycle. The arm will not stop when its 90 degrees (relative earth surface, but not relative rest position), it will travel 10-15 cm further and should therefore be extracted again before stop and go back. In one cycle it is fully retracted twice and fully extracted once.

As long it doesnt touch the glass its OK. Have You tried the mechanism in third position? (Full speed).

I didnt take off the black plastic cover, but there is probably some alignments mark in there.

Best thing would be to check one mechanism that is in a car assembled from factory.

Is there anyone out there with an unit that not has been tampered with?

This is an amazaing mechanism, truly over-engineered.

JH
 
#39 ·
I got the clip off and got everything switched out and put back in. Only one problem... I didn't mark for alignment and welp, now my wipers rest almost fully up. Basically they work, just backwards. Starting in the middle of my windshield. Moving down to "normal" resting position, finally moving back up to the middle where they rest until the cycle continues. Any help? I will keep scouring the forum but have done so all day with no luck. If I cant get it come February I will just take it to my mechanic and have him do it. Luckily he has 4 w140s and era specific MB tools too. Cheers ~Sean
 
#40 ·
OMG Thank you for all this info. Mine has started doing exactly this in the last month or so.

I found the replacement plastic gear here, includes instructions on replacement. (Odometer Gears .com)


Will post any questions as I go. Thanks again!

-m
 
#41 ·
well that went incredibly bad. I couldn't get the new gear on the post and ended up breaking it. Didn't know which way it went anyway (my old gear was in 4 pieces). so at least my passenger side wiper works still, while I order another gear.

is there a way to rig the main/driver's wiper so it will at least wipe without the gear?

thanks.

-m
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top