Changing the windshield wiper mechanism front and rear on B-Class W245

The major issue with this car which basically prevents me from driving it is a malfunctioning front window wiper mechanism. It rains quite a lot here especially in the autumn, also it’s illegal to drive without them. While the front window wipers are essential, the rear one is not working either. Side view mirrors are often enough, however the mirrors on this car are so small and “well” designed so you can’t really see whats directly behind you. So I will need to fix that one as well.

The front wipers were almost not working when picking up the car when I bought it and the wipers were stuck in a weird position. Unfortunately it was heavy rain this day and not really possible to drive without it. When inspecting the mechanism it turned out that the motor was fine, but the wiper bracket was broken due to a totally seized right side wiper shaft.

After some 2 hours of fiddling in the rain we managed to get the driver side wiper to work (barely). The drive home was quite interesting where I operated the wiper only when strictly necessary. Thankfully it worked all the way home with no fuzz.

Front Wiper Mechanism

The access to the front wiper mechanism is easily made with removing the plastic cover just over the engine beneath the front window. But first open the hood to get better access to the wiper arms. Some care here is needed so you don’t crack the front windscreen, such as dropping your tools and slamming the spring loaded wipers on the window.

Removing the wiper arms can be a challenge if you don’t know the trick. Unscrew the nut half way, then use an open ended wrench to pry off the wiper arm and voila it’s off. Once both wiper arms are removed, you can remove the plastic guard cover. It’s only held in place with 6 hex screws located at the top of the engine bay. Take care not to loose any tools or screws into the engine bay. You will never find them again from the bottom of the engine bay.

The wiper mechanism itself is easy to take off. There is one cable to the motor, then the mechanism is held together with 3 bolts. When reinstalling a used one, or refreshing the existing one. It’s an excellent opportunity to lube the wiper shafts with some oil and put some grease on the mechanism joints. Much easier than when it’s on the car.

Before reinstalling the wiper mechanism, make sure the joints are installed the correct way. Use the article as reference since there are two ways the joints can attach to the middle pivot bar. Installing them the wrong way might ruin the assembly when turning on the key. Also beware that the motor is really powerful, so don’t put your hand or fingers down in the mechanism while someone is turning the key or checking the mechanism from inside the car. Ideally the battery should be disconnected while working on the wipers.

Before assembling the whole thing, make sure the wiper mechanism works properly by turning on the wiper motor and inspect that the mechanism works without any issues and clears all obstacles under the windshield. There is some wiggle room for the bracket in the 3 mounts. Then you can put back the plastic cover.

Working mechanism, quite fun to look at.

Installing the wiper arms is probably the most difficult with this job, since it needs some fiddling and adjusting to get the correct angle. The two arms are not equal either so make sure to put them on correct to their assigned side. When aligning them, you will need to try them out and see if they have enough clearance when operating while also cover most of the screen. This might take a couple of tries, so be patient. When they are aligned, then put back the plastic covers and your are done.

The issue with this type of wiper arm design is that the wiper arms seem constantly to fight for position. If one binds or get stuck the other wiper will most likely break the other arm with a punch! A problem in older cars with more non-synchronized wipers like these is that they end up fighting for the windscreen and the wiper arms get bent, for example Lamborghini Espada.

Car is now capable to handle rain again!

Feels good to have working wipers again!

Rear wiper mechanism

The rear wiper motor is easier to replace. First remove the wiper arm, or if it’s broken off like mine, remove the nut. Then open the rear hatch, there is a plastic cover under there which can be removed without tools. Just use a plastic prying tool to snap it open.

The wiper motor has a plastic tube which needs to be unhooked. The plastic tube delivers wiper washer fluid to the rear window. Don’t worry, it will not leak water when unhooking it. Don’t mess up the plastic spring, otherwise you will leak washer fluid into the boot. Also unhook the power plug.

Plastic retainer to secure the washer fluid tube.

The window motor is held in place by only three bolts, and when removing these you can slide out the whole motor from the rear.

A new rear wiper blade comes actually wih a new arm as well, since the wiper blade is quite special and non-standard. It is not super cheap, buit not expensive wither. Installation is just reverse of disassembly, remember to test it and check for leaks before finishing at the end.

Working rear window wiper mechanism. Nice when spying on the cars behind you, not that there will be any cars behind this super fast 180CDI!!!!

My experience so far with working on this car is that it’s actually super easy to work on. It seems that if a car is easy to assemble on the factory thus making it cheap, it will also be easy for the home DIY mechanic to do work on. I’m quite happy for that. Older cars are usually more complex in their build and also a bit harder to work on.

Robs out!