ABS Pump loud noise & dash lights

[henrycg]

Hi,

Hope y'all can help- Recently when I start my 500E, the ASR/ABS pump (photo below) begins making loud and strange noises. It sounds like a loud slurping as if there is air in the pipes mixed with the brake fluid. It does this for usually less than 1 minute and then the pump completely shuts off as if it has some kind of safety cut off.

When the pump shuts off Santa visits my dash. A green, red and yellowy/orange ABS light come on on my instrument cluster- usually all together. The photo below shows the green light. Ignore the brake warning on the left, it was doing its job fine.

Note: previous owner changed the instrument cluster. This one has no light with ASR written on it.

But i have concluded that:
- Green (2nd from right) means ASR. It has no writing or symbol- just a blank rectangle. If it comes on i can get unlimited wheel spin. It used to always be joined by red but less so these days.
- Red (3rd from right says SRS on it it so i assume its airbags) Since I've owned the car, Red has never come on alone- only come on WITH green.
- Yellow/Orange (4th from right) is the ABS light i believe. It says ABS on it.

I figure I'll probably have to pull the pump out? Let me know your thoughts or experience.

Cheers.

The pump ^

 

[Klink]

Check for a siezed or inoperative ASR fluid pre-charge pump. That is the electric pump located under the master cylinder. It transfers fluid to, and primes the high-pressure piston pump in the hydraulic unit. Without an operational pre-charge pump, the high-pressure pump cannot generate pressure.

Also check the condition of the hose that carries the fluid from the brake fluid reservoir to that pump. Make sure that it is intact and not leaking any fluid or air.

The pre-charge pump has a simple rotary gear configuration, and they can seize from corrosion and / or debris. The pump end of the unit can be disassembled, cleaned and restored to operation in most cases. The high-pressure pump inside the hydraulic unit (behind the headlight) just about never fails.

 

[henrycg]

Check for a siezed or inoperative ASR fluid precharge pump. That is the electric pump located under the master cylinder. It transfers fluid to, and primes the high-pressure piston pump in the hydraulic unit. Without an operational pre-charge pump, the high-pressure pump cannot generate pressure. Also check the condition of the hose that carries the fluid from the brake fluid reservoir to that pump. Make sure that it is intact and not leaking any fluid or air. The pre-charge pump has a simple rotary gear configuration, and they can seize from corrosion and / or debris. The pump end of the unit can be disassembled, cleaned and restored to operation in most cases. The high-pressure pump inside the hydraulic unit (behind the headlight) just about never fails.

Thank you v much, I will check it out. I did have someone remove the master cylinder and put new seals on it when my brake pedal literally hit the floor recently. Maybe they disconnected the pre charge pump by accident while fiddling with the MC

 

[akki.rane3266.ar]

Can i check

 

[henrycg]

Update:
Embarrassingly I failed to notice a massive split in the hose running from the brake fluid reservoir.. This must have happened recently. Anyway I refilled the fluid and ran the car for a while the noise stopped and ASR light went off! ABS light on though so gonna check all the wiring over next few days. Will have to bleed the brake system now too since air got into the system. I haven't checked the precharge pump since I noticed the empty reservoir on the way there which fixed the problem so I assume the pump's working.

 

[Klink]

Update:
Embarrassingly I failed to notice a massive split in the hose running from the brake fluid reservoir.. This must have happened recently. Anyway I refilled the fluid and ran the car for a while the noise stopped and ASR light went off! ABS light on though so gonna check all the wiring over next few days. Will have to bleed the brake system now too since air got into the system. I haven't checked the precharge pump since I noticed the empty reservoir on the way there which fixed the problem so I assume the pump's working.

You got it right. If the ASR lamp switched off, then the precharge pump is definitely working.

 

[henrycg]

You got it right. If the ASR lamp switched off, then the precharge pump is definitely working.