W205 C250 windscreen washer reservoiur won't fill!
 

I have just bought an 18 month old C250D and the washer jets are very weak. I can only top up with 100ml fluid before its full. The jets are very erratic from a half hearted spurt to a dribble - it looked like the pump was being starved for some reason so using a long tube I drained what fluid there was - not too much and its 'full' with 150ml. Seems to be some sort of blockage between the filler tube and the main reservoir. Any ideas? The dealer is some way away and can't book the car in for several days. As per modern cars there is no easy access to see what is going on

I bet they used a RainX containing substance in the reservoir. Try pouring warm to very warm water over the jets to clean any film left by the previous fluid. Then, refill with ONLY a pure washer fluid without any other additives, or pure distilled water so it doesn't have any minerals. You can also try vinegar diluted with water, but make sure you exhaust that fluid completely and use it to only clean the system. It is acidic.

The washer pump grommet/filter gets clogged. Remove the left front wheel, remove the back half of the inner fender plastic, and pull the pump up and out. There will be no liquid coming out. Remove the rubber piece the pump goes into, clean the crap off of it, and put everything back.

Am going to borrow this old thread. I recently bought my car an have a problem where my nozzles freeze despite having sufficient mixture of washer fluid. Never experienced this before and now I have a theory that perhaps there is some kind of soggy watery residue which is the one freezing? Did anyone experience something similar ?

Hi,

I understand I'm a bit late here but I'd like to make a post here to share my knowledge as I've had 3 separate clogging issues over just the last month and I've only now just discovered the cause and permanently fixed it. I'm assuming your pump is functioning normally and you don't have any leaks in your lines.
I've had a similar experience where there was some sort of "soggy" substance in my reservoir which would clog 2 places: 1) the 2in1 gasket/filter MB have used for some years now 2) The waterjets that spray onto the windscreen. This will at first cause low pressure and then get completely blocked.

Possible fixes I recommend in order:

• Step 1 (Possible cheap fix): If you still have some water flow attempt adding a cleaning agent to your empty reservoir. A 1:1 ratio of water to distilled vinegar is what I used but you can search for some proper cleaning agents if you'd like. I would try to add at least 1L of this home made solution. Once added run the wash jets for a couple squirts so to let the solution make its way up. Let it sit for as long as you can and preferably overnight if you have the time as it'll let the solution break apart this soggy substance as well as any other dirt and debris in the filter, and jets. Continue to squirt and empty the reservoir, repeat this process as many times as you like. You can also always add a small amount of vinegar to every top up to keep it clean.
• Step 2 (Free but time consuming): Get to your reservoir by removing any trim in the way. Pull out the pump and you should see there is a gasket/filter, this is the first thing that tends to clog up. Remove this little filter and rinse off any dirt and debris until you can see all holes are clear. I won't post a link but there is a video on YouTube you can search for how to get to it for this car.
• Step 3 (Little costly): If still having low pressure following the first 2 steps, try replacing your line from your pump onwards. It just tends to be just 1 whole unit that has a sensor and built in water jets. I got mine for 50 euro from Mercedes as it was a heated system and you can't by the parts individually. As its a heated system if cleaners don't help I wouldn't recommend taking it apart or using a needle to clean the nozzle.
• Step 4: Use a good quality screen wash that wont freeze in your climate. Water expands when it freezes which will cause damage, water also likes to have stuff grow in it. I've tried a few different screen wash, some would cause the clog to come back nearly instantly and some wouldn't for a while but then eventually show up. I get my screen wash through Mercedes on Ebay as pricey it may be for some(15 Euro for 1L of concentrate), it's worth it in the long run since I don't have anymore clogging or low pressure.
• This issue started for me as soon as I started using a different brand of screen wash. I had done 50k miles 80k kilometers using only Mercedes screenwash. Once changing to another brand issue occurred, it didn't stop until I done all the above steps and then went back to Mercedes screen wash. I'm sure there's equivalent quality but cheaper alternatives out there but I don't want to experiment and the cost for me is perfectly affordable.

TLDR:
- Put cleaner like vinegar in reservoir
- Clean gasket/filter for the pump. VERY COMMON ISSUE for BMW and Mercedes cars.
- Replace the washer jet pipe assembly unit (pretty easy and quick and inexpensive)
- Use good quality screen wash. Never let the water freeze! It can/will break things in system. Screen wash = Cheap however Sensor, pump, heating system = Expensive

I hope this helps some people in the future reading this and that I've made people aware that this is a more common issue than some would think!