W124 Wiper Function Question
 

Hello, I have been reading the forum for some time, but now have a question that I have not been able to resolve on my own.

I have two W124 300D's.

The uni-wiper on my '87 started to slow a bit on portions of it's sweep. On the advice of a master Mercedes mechanic, I used a product called Tri-Flo on the obvious moving parts. Which fixed (for now) the problem.

Then I got to noticing a difference between wipers on my two W124's: on the car that had the problem, there was very heavy/obvious rub/wear between the long cover (just above the "turtle shell" hub) and the arm. The part the moves in and out, just above the center hub.

The other car, no wear at all in this area. Appears to not touch at all.

Is it normal for these two parts to rub on each other?

No, of course MB had a split contract on that system.

Bosch made about 60-65% & SWF had the rest of the contract.

Parts are not interchangeable between the 2 vendors.

Which brand(s) does your cars have on them?

I have a Bosch and the plastic snap-on cover rubs the clamshell. After 19 years it has rubbed the paint off, but I consider this normal as there is nothing I can do save for removing the plastic cover altogether.

I do not know how to tell the difference. Any suggestions? Does one brand rub and the other not?

Only way I could find out was to remove the wiper mechanism and take it apart. The Bosch logo was cast into the inside of the clamshell.

I wouldn't worry about it really.

Mine had the hinged metal cover and it "click-clacked" all the time the wiper was on. Very annoying. I swapped the arm with another that had the plastic clip on cover and it works fine. Still rubs a bit but no noise.

The metal cover is now a great bottle opener:D.

I can't even figure out how to get the metal cover OFF !

Are we talking about the little clip on cover? If you mean the big clam shell thingy then you have to remove the whole assembly and unscrew it from behind. Which is not a bad idea if it's never been greased up since new.

There were two types of plastic slip cover on the arm connection to the motor unit. An early type with an inspection hole and flap and the superceding type that does not have the hole and flap.
The 'clamshell' metal head on the gear unit can only be removed with the whole gearhead mechanism out of the car. The 'clamshell' is plastic and supposedly removable in situ on the second facelift cars - those with an inset grille.
Stiff and slow wiping will be down to dried up grease - it turns to hard wax - inside the gearhead. I had to strip and re-grease a 1992 wiper unit about 5 years ago to cure that. A short term fix is a few drops of 2 in 1 oil on the metal rod that the wiper arm bolts to.
I stopped the wiper when it was vertical on the screen, lifted off the plastic slip cover, slipped a rag underneath to protect the glass and oiled the shaft lightly.

The car I worked on had a Bosch motor and gear unit, although the spare motor we bought turned out be an SWF item.

What kind of grease? I just disassembled one. The factory grease was not dried up; it was dingy and old looking, but still greasy. Wasn't very much of it though. I have a theory that they're not supposed to be greased to death, just a little in the right place is sufficient. I didn't clean the old grease out because it was still pretty greasy, not waxy or gummy. Instead I redistributed it and added a little bit of MB Gleitpaste to the plastic teeth. Not sure whether that particular grease is appropriate for the job, but with all the talk about how great that stuff is I thought I'd try it on the wiper gear.

If the wiper slows down it could be from friction with the pistoning rod inside the clamshell. I had this trouble once driving through a blizzard. I think the combination of the rod being dry and the cold caused this condition. A little transmission fluid on the rod fixed it. This leads me to believe that it's not necessarily the gear inside that causes the problem, but the stiction with the rod that overwhelms the gear inside that leads to stripped teeth. Old grease on the gear exacerbates the issue.

Yes,you've got the "Program". (Friction)
 

"If the wiper slows down it could be from friction with the pistoning rod inside the clamshell. I had this trouble once driving through a blizzard. I think the combination of the rod being dry and the cold caused this condition. A little transmission fluid on the rod fixed it. This leads me to believe that it's not necessarily the gear inside that causes the problem, but the friction with the rod that overwhelms the gear inside that leads to stripped teeth. Old grease on the gear exacerbates the issue."

1.Old (Or "Missing in Action") Grease.
2.The "Gears" (Plastico) that the O.E. supplier "Gifted" Mercedes with are of
Inferior quality to the New Ones available from Odometergears.com .
3. I'd stick with whatever the "Required" Lubricant is from Mercedes
OR the Gleitpaste.
(I'm experimenting with Diawa synthetic super lube for fishing reels...
Saltwater Impervious,Not affected by Heat or Cold.)

I think the guy from Odometergears hit the big time & contracted with Performance Products. You can buy wiper gears from them now as well, same price.

the facelift models have a removable plastic clamshell - I applied some general NLGI2 wheel bearing grease to the slider pins and the wiper arm piston that sticks out from the end and clipped it back on - this exercise smoothed out the clanky noise it had and sped up a little too.

The old grease was kind of waxy and pretty hard and nearly non existant on the bottom two sliders