ATXJosh

My windshield washer requires 2 - 3 presses of the stalk before it'll pump fluid out. On the first one or two, it'll squirt just a bit out, and then it cuts off. But by the 2nd or 3rd press of the stalk it works fine, and continues to work fine if used again fairly soon after. But let it sit for a few minutes, and it requires multiple presses again. When outside the car, you can hear the motor just shut off.

This is a recurring problem and it has persisted through 3 stalk replacements. Not sure what else to do about it. I've read in the forums that this is a fairly common problem, but nothing really about how to fix it if a stalk replacement failed to correct.

samaritrey

Sure its not a pump issue or wiring issue?

ATXJosh

No, im not sure about that. The pump works just fine - you just have to press the stalk twice. Im wondering if it has something to do with a back flow valve and some sort of safety measure on the pump motor - i.e. bad valve is letting fluid drain back into the reservoir and the motor cuts off because it doesn't detect fluid being pumped.

Moviela

What kind of fluid are you using? Genuine Mercedes or the blue stuff from Wal-Mart? The blue stuff leaves behind calcium in the pump and the nozzles. You can clean the nozzles with a Klann tool, and soak the pump in vinegar to clear the impeller.

You push the button several times because the pump is frozen, and it takes a few applications of current to free it. Once free it will start on the first push until the calcium forms again.

Stop using generic washer solvents and tap water in the washer. Use the Mercedes fluid (mostly alcohol and mild soap) mixed with distilled water. There are other brands like Wurth Speedy Windscreen Cleaner that work as well as the Benz product. Use the washer a couple times a week at least to prevent scale from forming.

It is possible that the motor is just to gunked up for vinegar to work. I have had luck soaking only the pump internals with CLR "as seen on TV."

ATXJosh

Im personally using RainX brand, definitely not genuine mercedes. I can't speak for what the previous owner used, i would imagine not mercedes brand.

I'm sorry, I confess ignorance here, but what is a Klann tool? and are there any instructions on how to remove the pump for soaking?

ATXJosh

nevermind, i found something in the search tool.

ATXJosh

any recommendations on where to get genuine washer fluid beyond the dealership? Not coming up with much on the google front.

ATXJosh

so i soaked the pump in vinegar.... actually doesn't fire at all now. so just going to replace the motor considering how easy it was to actually take out.

ATXJosh

ok... so i changed the pump out... still requires 2 - 3 presses, so definitely not a calcium build up now. Any other ideas?

Moviela

Klann Tool, no Mercedes should be without one.


I would check the terminal voltage at the pump. Should be 12 v when button pressed. If too low there will not be enough inrush current to get the motor moving. Can be a bad ground connection, corrosion on the motor terminals, or at the front SAM.

The button on the steering column does not actually fire off the pump. It sends a request on the canBUS to the front SAM. If there are too many users chatting on the bus the request may be ignored. This can be caused by things like dicey switches for windows, lights, and steering wheel, or modules like those for the seat that don't sleep when done. These problems can be hard to find without Star diagnostics.

funnyent

I have the same problem, wish I could help but I just live with it. I also had tried soaking in vinegar, but just like you it didn't do anything. Strange problem with these cars.

ATXJosh

Well here's the even stranger part... It only does it when the engine is on. If the car is simply in the "on" position, washer pump works fine.

The next time i have the old girl into my indy mechanic, i'll have him hook it up to his star tool and tell me the errors, but to your point, will likely just live with it. Not all that interested in dropping $400 to have him work on the something just to save me 2 seconds pushing the button an extra time.

VVF

I always though the delay is because the fluid takes some time to travel to the nozzles...
Otherwise too many of us have this problem. Weird.

ATXJosh

There is a little bit of a delay in my Passat as well, but the motor keeps going and you can hold the switch down. It's just weird that you have to push the button several times instead just holding it down if that's the case. At this point, my conclusion is that it's either the front SAM being squirly or some back flow valve that i can't find on the parts diagram has failed. My gut says it's the SAM since my passenger power seat adjust is acting up as well (if you pull back on the button to give more leg room in the front, the read head rest goes up as well at the same time). Either way, I've reached the limit of what my limited skills can do in the garage. Not bother enough to rush into the mechanic, i'll have it checked out the next time i need something else done.