phomat

I recently flushed my ABS system. Filled it to the proper level. Worked fine for a few weeks, then I noticed a puddle under the reservoir and a warning on the dash to take it to the shop. The fluid was overflowing the reservoir. When running it's now low, but when it's shut off, it comes up to the top of the filler. Any ideas?

White Spyder

latemodel21

both of your symptoms are consistent with pulsation dampener failure(s).

the dampeners (mounted at the valve blocks and 2 other locations) will release their gas when they fail causing a "burp" in the system (which causes reservoir to overflow) AND, when vehicle is running, they now have a greater volume to fill (causing your lower level while running).

searching the forum using "pulsation" will lead you to more specific info. https://mbworld.org/forums/search.php?searchid=23049032

hope that helps,
Chris




EDIT ... of course I meant "accumulator" and typed "pulsation dampener" ( though they are essentially the same)
the resource that Rudeney linked is VERY good.

For some reason I had always thought that a blown accumulator would increase the change in level between running and not .... but I may have that backwards (I suppose I would only be right if the accumulator were higher than the reservoir)

Chris

phomat

I meant ABC. Thanks.

Rudeney

See here:

http://mercedes-abc-drive-carefully.blogspot.com/

Probably a blown accumulator.

bobterry99

As noted, if an accumulator fails its nitrogen gas can make its way to the return reservoir and push oil out of the reservoir. That said, I believe the following is an indication that your accumulators are fine:

A litmus test of the front and rear accumulators is driving over a speed bump at c. 10 MPH. A faulty accumulator will allow a low-pressure spike in the ABC oil supply and cause a momentary fault indication in the instrument cluster. Also, your Star Diagnosis' DAS program diagnostic program can identify a failed accumulator.

White Spyder