B class Windscreen washing system issue

Braincrank · Oct 10, 2022

Hello all.
I couldn't find any answers in previous posts, so here goes:
A couple of months ago I noticed that the windscreen washer system had a delay before the washing fluid reached the jets.
I had to drive a few miles before the liquid reached the jets. Now it was stopped completely. Washing liquid tank is full and not cloudy.
Does anyone have any idea what could course that, or where I should start looking on my quest for finding the fault?
Kind regards and thank you in advance (-:

colinallcars · Oct 10, 2022

Braincrank said:
Hello all.
I couldn't find any answers in previous posts, so here goes:
A couple of months ago I noticed that the windscreen washer system had a delay before the washing fluid reached the jets.
I had to drive a few miles before the liquid reached the jets. Now it was stopped completely. Washing liquid tank is full and not cloudy.
Does anyone have any idea what could course that, or where I should start looking on my quest for finding the fault?
Kind regards and thank you in advance (-:

The outlet filter at the bottom of the reservoir is probably blocked. It’s incorporated into the grommet that the washer pump is inserted into. It’s located below the left, front headlight - pull back the wheel arch liner for access. You need to unclip the pump and push it upwards, the grommet can then be removed and replaced (about £5) or cleaned. You’ll find it’s full of gunge.

Braincrank · Oct 10, 2022

Thank you very much for your detailed description. I'll check it out next time I have a few spare minutes

Braincrank · Oct 13, 2022

colinallcars said:
The outlet filter at the bottom of the reservoir is probably blocked. It’s incorporated into the grommet that the washer pump is inserted into. It’s located below the left, front headlight - pull back the wheel arch liner for access. You need to unclip the pump and push it upwards, the grommet can then be removed and replaced (about £5) or cleaned. You’ll find it’s full of gunge.

I guess that is the filter you mentioned?

colinallcars · Oct 13, 2022

Braincrank said:
I guess that is the filter you mentioned?

It doesn’t look like it, the one I’m thinking of actually has the pump inserted into it. It’s common to a number of Mercedes models but perhaps different on yours? You don’t mention what model you have,
looking it up in the appropriate diagram may help.
Automobile portal WebAutoCats.com.

geoffus · Oct 13, 2022

Is this the reservoir behind the nearside wheel arch ?

Braincrank · Oct 21, 2022

geoffus said:
Is this the reservoir behind the nearside wheel arch ?

It's a left hand drive, the reservoir is in front, left, behind the headlight
Chassis no is :
WDD2452071J05636B

colinallcars · Oct 21, 2022

Braincrank said:
It's a left hand drive, the reservoir is in front, left, behind the headlight
Chassis no is :
WDD2452071J05636B

It’s a 245. Sorry, I’m not familiar with that model.

FiveAlive · Oct 21, 2022

Not clear what you mean by "I had to drive a few miles before the liquid reached the jets". If you need to run the washer pump for a while before water starts to come out, that suggests that a one-way valve in the system has failed, causing the water to drain back into the reservoir. If you have to let the car warm up before water comes out, that would suggest the water has frozen (though your location is given as London so that seems unlikely).

They are prone to gumming up if different brands of screen wash are mixed together, but that usually requires everything to be cleaned out by hand before it will work and you say that your fluid is not cloudy.

The system itself is simple (reservoir, pump, pipes, jets) and the reservoir with pump is easy to remove from the car: just turn the yellow knob and ease it out, keeping an eye on the pipes and wires underneath. Much more accessible than the under-the-wheel-arch layouts of other cars.

Braincrank · Oct 21, 2022

Thanks for your answers.
What I meant with running the car a few miles is that when I start the engine and press the washing button, there's no fluid coming out. Once I drive a while and try again, then the fluid will start to come through the jets. It's definately not frozen

.
It just seems to be related to having to drive a bit before it starts working. But that could be my imagination.
I'll check it out next week when I'm home.
Do you know if there is a filter in the system? Could it be the one I circled in my Pic, or it that the back flow falve?

colinallcars · Oct 21, 2022

Braincrank said:
Thanks for your answers.
What I meant with running the car a few miles is that when I start the engine and press the washing button, there's no fluid coming out. Once I drive a while and try again, then the fluid will start to come through the jets. It's definately not frozen .
It just seems to be related to having to drive a bit before it starts working. But that could be my imagination.
I'll check it out next week when I'm home.
Do you know if there is a filter in the system? Could it be the one I circled in my Pic, or it that the back flow falve?

Why not just dismantle it all and give it a good clean? It’s bound to need it at its age. Replace any disposable filters too.

Braincrank · Oct 24, 2022

colinallcars said:
Why not just dismantle it all and give it a good clean? It’s bound to need it at its age. Replace any disposable filters too.

That's the plan

Just thought there might be a EPC diagram which shows any filters / valves in that washing system.

Braincrank · Oct 24, 2022

colinallcars said:
Why not just dismantle it all and give it a good clean? It’s bound to need it at its age. Replace any disposable filters too.

That's the plan

Just thought there might be a EPC diagram which shows any filters / valves in that washer system.

colinallcars · Oct 25, 2022

Braincrank said:
That's the plan
Just thought there might be a EPC diagram which shows any filters / valves in that washer system.

Have you tried the link I posted a few posts back?

Dave Richardson · Oct 25, 2022

If the filter is blocked, flush it & then only use the genuine Mercedes screen wash, the cheaper stuff just clogs up the filter

geoffus · Oct 25, 2022

Dave Richardson said:
If the filter is blocked, flush it & then only use the genuine Mercedes screen wash, the cheaper stuff just clogs up the filter

I've never used Mercedes screen wash on either of my Mercs in the last 4 years, never had a problem with cheap screen wash clogging.
I have read that a couple of Steradent tablets placed in the reservoir for a couple of hours helps to clean the system, though never tried it.

Braincrank · Oct 26, 2022

colinallcars said:
Have you tried the link I posted a few posts back?

No, gonna have a look if I find it

Braincrank · Oct 26, 2022

Braincrank said:
No, gonna have a look if I find it

Found it
Thanks for that

Braincrank · Dec 20, 2022

That issue was sorted a while back now. It turned out to be the pump that was not working.

RLarkins · Jan 9, 2024

I have a 2006 b class and while each front wiper jet has 3 nozzles the LHS works fine but the RHS has one nozzle good one poor and one seeming blocked.
On other cars I have had inserting a needle in the steel ball helped to clear it and could also be used change the direction of the water jet but the holes seem v small and no obvious balls, please can anyone help