How much of a problem is your mono wiper?
 

Just in general, I'm wondering how much of a problem your mono wipers is. I've had to replace my internal gearing which fixed the hardest problem of having to take the monowiper apart. That was no fun but the new plastic toothed gear-like running track fixed that completely.

But the problem now is the motors. I'm going on my 3rd re-manufactured mono wiper motor in 5 years. I think the original Bosch mono wiper motor on this car lasted 21 years, nearly 1/4 century.

I got a re-manufactured Bosch by Cardone 5 years ago and it lasted for 10 months. Fortunately they have a lifetime warranty on them so I got a free replacement. That one lasted about 4 years and now the intermittent wiper mode is not working.

I'm glad for the "lifetime warranty", but it's a lot of work to change these out. I don't want to be doing it in 10 months again with the new replacement one. I was tempted to pay $50 extra and just get a brand new one but they don't have lifetime warranties on them. :(

If you don't want to replace it, don't buy Cardone. They're absolute trash. I've never replaced any on any of my cars and I'm sure they're all originAl.

What good is a warranty on a part if you have to keep on changing it out? A wiper motor should last for decades unless it's a Ford. I'm pretty sure their normal supplier is Cardone...

I had one die in my '95 sedan, replaced with a used assembly from pick-n-pull and no problems with the "new" wiper for a few years. The "new" wiper is OE.

I have a '98 e300 and still have the original motor; I've had no trouble with it. I buy a new wiper blade every 12 to 15 months. An advantage of the mono is that I buy only one.

I'd suggest buying a working used one, replacing all the grease in it, and then using it. It should really last pretty much forever if its kept lubricated.

The wiper motor in my 190D is going strong after 31 years. About 12 years ago, I disassembled the transmission for clean and lube. That's about it.

Owned several used MB's over the years with the monowiper. I never had any problems with any of them. They just worked, didn't have to touch anything.

If the intermittent doesn't work but the other speeds do the problem is not the motor it's the relay that controls the intermittent function.

Interesting! Where's the relay?
 

How do I fix/replace the relay?

My w126 has a mono wiper.
 

I didn't own it long before I figured out that the left blade wears out before the other one. I removed the wiper arm on the right side and the LS cleans the windshield just fine, good enough for me.

That blade will last two times longer because it isn't wiping a dry area constantly. I still buy blade two at a time.

I've generally had good success. On my 91, there's a problem with the transmission such that the arm doesn't fully retract. For the time being I've installed a shorter blade and am not overly motivated to get it repaired.

+1 on junk yard rescue and rebuild yourself.

For those above who asked, where is the intermittent relay?
124 and 126 it is N10 relay, the second largest relay in the box. This also carries your turn signal flasher and rear defroster control/timeout. These are all straight wired circuits, fuse to switch to motor.

The intermittent relay pulses the motor off and on intermittently. What it actually does is makes the motor go into a “wipe once then park” just the same as if you twisted the switch to II and then back to 0. I did a writeup on how this works a while back. http://www.peachparts.com/shopforum/3667285-post27.html If you are having trouble with the intermittent, and swapping N10 does not help, then chances are the park/run switch is the issue.

210 it is integrated into the N10 and K4/1 front SAM in the back of the fuse box. There is no intermittent relay per se, there is only a high speed and low speed relay. The intermittent function is calculated from the logic in the front SAM. If you have a rain sensor the N10 gets CAN bus message about % obscurity from N72 the overhead control panel. The actual command to run the wiper is indirectly controlled from the stalk switch. The stalk switch does not switch the motor current, it only switches different resistors onto a control line that ends up in the ignition switch. In the switch the resistances are read and translated into CAN bus messages that go to the front SAM. The front SAM interprets these messages and closes the correct relays to operate the wiper motor as required.

Same on a W201. it's the big black relay in the back of the box.

As an aside, there's a wonderful movie about the development of the intermittent wiper, called "Flash of Genius". It's must viewing for anyone interested in automotive history.

Flash of Genius (2008) - IMDb

My problem with mono wipers is speed. I never owned one of these cars new but at the age I get them, max isn’t fast enough for a downpour or bad road spray. Not a frequent issue around here but a cause for concern. jay_bob, can you rewire the relay for a 90* quick sweep?

Sixto
98 E320s sedan and wagon