C-rod

I purchased some WW fluid today and I was going to top off the reservior, as I was pouring the fluid, I heard a dripping sound coming from the bottom..yes out came the fluid I was putting in ????? Beautiful.......Has this happened to anyone else.....First a leaking water pump and now the WW reservior ???

DeathBlow

Did you over fill it? I know some WW reserviors have a bypass after you reach a certain hight. I dont know if the ML has one.

eeferber

that happened on my '99 430ML, maybe when it was 5-6 years old.

The reservoir developed a crack high up on the tank (don't recall exactly where). Never noticed a problem until, like you, I filled the tank to the top, and of course over the crack. Started leaking like a sieve until it was below the crack again.

I had it replaced under a 3rd party warranty.

dgiturbo

The reservoir leak does happen to some of these ML vehicles. I think it is a 2 piece design, (bottle and filer neck) and where they meet is the issue.
What was the issue with your water pump? Where did it leak?

C-rod

Makes sense, a two piece application.....it only seems to be leaking at the top. As for the waterpump, I was experiencing some cold morning sqeauks last winter and when they were replacing some belt, they noticed the waterpump was leaking, so they replaced it. I am going in this coming Monday, for the WW tank, some apparent noises in the front suspension area....and some ticking noise coming from the engine area, on some cold morning starts...Hmmmm..what are ya goin do ????

eeferber

yep, I remember now - it was cracked at a seam.

troby

Soon after I purchased my ML, in 2011, I discovered the same problem. (I almost had a hard attack 'finding' a 'defect' in my new car.) Went immediately to dealership. They put the car on the lift, removed the front bumper, and showed me that everything is OK, the reservoir was full, and no leak. However I was not able to see all components layout and their exact location.

Reluctant, later, I started the internet research.

I found a diagram from a parts sales supplier that showed a "Filler" on the top, connected to a "Reservoir assy". Between the "Filler" tube and the "Reservoir" there is a "Filler Seal". My guess is that the seal is not perfect to not create a vacuum inside the reservoir when liquid is pumped out from reservoir. And in my opinion this is the 'weak link' that allows the liquid to leak.

Personally I suspect that MB engineers choose this design due to space constraints inside engine compartment. They had to lower the placement location of the washer liquid reservoir, and added the 'Filler' part.

I never saw in my car the WW liquid topped at the "Cap". Immediately after I fill the "Filler", the liquid is at the top. One day later I can not see the top of liquid, like in other vehicles. And the entire liquid volume of the "Filler" (approx 1/4 gal) is lost, or if the "Cap" is left open immediately drips on my shoes.

The "Reservoir" has a "Level indicator" which, I think, sends a signal to the instrument cluster when the quantity of liquid is low. But I never saw such warning in my car.

Hope this helps.