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Windshield and headlamp washer pumps

Started by alicate1, 31 July 2023, 10:14 AM


Hello, this is my first topic in the forum so many thanks by the opportunity, sure I will find lots of info to fix my recently acquired W116 350SE from 1973, only one previous owner, sold and kept in Spain. 160.000km real at the odometer a lots of extras.

The car was well kept in garage 12 year so it has some updates but still needs some checks, deep cleaning was already done.

My point now are the washer pumps, windshield and headlights. When I activate the windshield wipers they work properly but continue pushing the wiper switch there is no water spread. Either the headlight´s pumps when lights on.

It seems the steering wheel switch is working so, regarding electrical diagrams, the next to check is the relay and wiper motor connections.

Do you know where the washer pumps relay is located?
Is there available any tutorial about wiper motor removal?
In order to check connections or relays if were there.

Many thanks and regards in advance. Great forum.

I checked and the pumps are OK, but no energy supply is arriving to any of the pumps.


Welcome alicate1,

Im not sure if there is a relay for the washer pumps.  The pumps are located below the battery tray and are completely separate from the wiper motors.  Getting to the wiper motors is easy, remove the arms, then the body panel and you will see the entire motor.

It could be a worn out switch. 

Stalk removal:  Then you could apply 12v to pump leads and verify if stalk is bad.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,


Thank you very much for those links, they will be useful.

I will change the relay close to the pedals, if it does not work I will go to check wipers motor connections, and finally the stalk switch.

I will let know to the forum for everyone knowledge.



The motor in the pump can and does fail.   First I'd check that the pump is getting power before replacing stuff, searching for relays etc.  There's a good chance that it is.  If so just pull it and replace.  Pumps are available for not too much $$$. Cheers,

edit:  also, there are small check valves behind the nozzles in the bumper.  They also can fail and get stuck shut.  If the pump is buzzing when powered it's likely OK.  Then check these valves.  They need a surprising amount of pressure to open.
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0


The pumps are cheap, but it's easy enough to test them for operation before replacing them.  In the end I had to replace the pump and the stalk switch to get everything working.
1977 280SE
1983 300D (sold)
1988 BMW 535is
1999 E320T (sold)
2009 E350T (wife's)


The small pump gears can also get stuck together. That's what happened to mine due to too little usage.
You have to get the pump out and unscrew the house to clean and regrease the brass gear wheels.
Rather straight forward in fact.
1974 W116 450 SEL 340.000km
Black exterior (040), olive green velours interior (966)


Hello, it solved. There were several problems:
- 1 pump didn´t work, I fitted new for both.
- I didn´t know about the wash pedal, I though it was a relay at the electrical diagram. It does not appear clearly at the users manual. Very bad from my side.
- Now is the turn to synchronize the headlight wipers.

For the forum knowledge, the relays involver in pumps and wipers are:
- OEM 1238210063 located at the pedals area.
- OEM 0335320006 regarding others dialogs in the forum, it is located back the fuel/oil/temperature gauge.


Many thanks for all your comments!