BenzWorld Junior Member
Date registered: Nov 2011
Vehicle: 1988 300E Factory 5 - Speed, 1990 300SEL, 1999 ML320, 2005 ML350, 1963 Corvette Roadster
Location: Hudson WI
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I just did the Windshield Wiper R&R on my 1988 300E. I would think it is the same wiper assembly. I wish I had taken some pics to help you out. Good advice from the other members. The “Gleitpaste” mentioned by Real1 is probably the best lube, but I just used a high quality synthetic grease and it worked fine. The advice on marking everything is important. I did not, and my wiper timing was all screwed up on reassembly. I had to take it all apart and figure it out from scratch.
In my mind, there are two unique mechanisms to the assembly; the transmission that connects the electric motor to the head unit, and the head unit itself with the articulating arm. You want to make sure that the whole assembly is in the “Park” position when you remove it from the car and begin disassembly. Note the position of the transmission arm (it has like a cam device) in the parked position. **Also note that in the park position the articulating arm is all the way in (not extended). It is necessary to remove the large nut that connects the transmission to the head unit to begin dismantling the head unit. You should be able to remove this nut without disturbing the position of the transmission; I did. It is a press fit so you will have to apply some force to separate the arm once the nut is off. Once that large nut and arm is removed from the head unit shaft you can remove a few washers and then a snap ring. Keep track of the washer positions on the shaft, there will be washers in different layers of the shaft above and below components. Not a big deal, just keep track of them. Once the snap ring is removed the shaft is free and you can separate the head unit case with this trick. In order to separate the head unit you need to rotate the articulating head (just as if the wiper were running) to what would be the center of its arc. There is a breach in the lower case at that location that will allow the case to be separated. It took me a while to figure this out, and frankly, where I screwed up. **I did not pay attention to the fact the in the park position the articulating arm has to be all the way in and as I had to move the head to separate the case, I lost track of it. Anyway, with the case separated you will see the gears responsible for the arc of the wiper across the windshield and the lack of grease. You will also now see all the screws responsible for keeping the articulating arm case together and you can now disassemble that assembly. Clean thoroughly, grease, reassemble and install. **The guys that designed these cars are pretty logical cats and I found that if I loaded the articulating head assembly in the arc assembly part of the head unit with the articulating arm all the way in (not extended) it ended up all the way in (as it needs to be) in the park position. The only other thing you need to be aware of is where you want the wiper to be on the windshield in the park position. I just eyeballed it and it worked out perfect. I hope I haven’t scared you off the job with my long winded explanation of the procedure. It really isn’t that hard or complicated once you get into it.