PeachParts Mercedes-Benz Forum - Replacement of the ABS/ASR pump

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Replacement of the ABS/ASR pump

Has anyone ever removed and replaced the ABS/ASR pump (car in question is a 94 e320 w124/m104). The ASR/ABS pump on my car makes a clicking noise on start-up. The noise quits after a minute or two BUT - the ASR and ABS work only intermittently (no ABS or ASR malfunction indicator lamps or "limp-home mode" symptoms). If the ABS or ASR engages during a trip I can again hear the pump making the same click-click-click noise as it did on start-up. Often after the ASR or ABS has engaged once it will stop working until I restart the car.

I bought a used ABS pump off ebay and would like to replace the one in my car to see if that fixes/changes the problem. There are quite a few brake line connections that I need to make, the pump ground, and the electrical connectors. Once I get the new pump in there, what is the proper procedure for bleeding the ABS/ASR system pump? Can anyone give me advice or suggestions otherwise?

Thanks!

BTW> I did quite a bit of searching around here and can't find anyone who has written about replacing their pump. I only found one 98 e320 owner who had a leaking ABS pump replaced by the dealership.

Does anyone have pdf 42 - 0816 or 42 - 0818 from the online manuals?

From this page?

http://skinnerbox.steaky.org/service/W124/Index/Groups/42BrakeSystem.htm

I wish that the .pdfs were still working!

Thanks!

I ended up replacing the pump (I have ASR so it was the larger, ASR/ABS combination hydraulic pump) and it cured the rattling/ratta,tatta, type noise.

To bleed the ASR/ABS pump you have the car running, open the bleed screw to let fluid out, then close the bleed screw. The pump should run for approximately 30 seconds - don't turn the car off until you hear the pump stop running. Also - make sure you have adequate brake fluid in the reservoir at all times.

Also - replacing the pump isn't hard at all. The most difficult part is loosening the brake lines. Make sure you have a brake line wrench also known as a flare-nut wrench (11 or 12 mm I think).