mhh

I've looked for old threads on this topic, but can't seem to find the answer.

Why does my E500 Wagon make a pumping noise from under the hood for a few seconds on starting? It goes away quickly but then comes back periodically while driving . It has a noticeable vibration that goes with the noise. Is it the air suspension pumping up or something? Can it be fixed? It has done if from new and the car now has 6000km.

Thanks for any ideas.

mhh

X72

A quick search turned up this thread
https://mbworld.org/forums/showthrea...&highlight=SBC

Suggest you search more terms involving the following terms alone or in combination: SBC (sensotronic) brakes, pulsation damper. I think you are hearing the SBC system. Well documented on this board.
William
2003 E 320

mhh

Thanks William!

I'll check it out.

mhh

ATS

It is a normal sound, you will get used to it doing its job.

steph280

I don't know if I will ever get used to it. Just when I learned to ignore it, I was reminded by a friend "what is that noise?"

You would figure with all the effort Mercedes spent trying to quiet the car, they couldn't use a quieter pump?

ATS

There is a TSB for this and I had it repaired under this and now I barely hear it.

lennylam

I would rather leave it like that. At least you know the SBC pump is working.

mhh

Just to clarify... the noise is the brake system, and not the suspension, right?

steph280

Then I'd bet you would love squeeky brake pads, too. So you know they're working.

lennylam

Squeeky brake means some sign of worn out. My newly replaced brake pads doesn't squeak. If you got squeeky brake, you should check it out - brake pads may wear down to 20% or less.

The sound from the SBC module sounds like charging the air pump. The sound from the suspension sounds like the something leaking air and you should be able to see the car goes up or down.

I guess you never experience anything failure without any warning sign especially on this car. I drove E500 and most of the issues came up without any warning. "Low rider" type suspension problem without warning - the car was jumping up and down on one side when the suspension failed. Luckily it is not happening on the freeway. If it happened on freeway, probably I am not sitting here and typing now. All turn signals, gas filler door was not working (Only have 4-5 gallons gas left) without any warning when I was 80 miles away from home. Finally, the heater on my car just failed last week without any sign of wear and tear.

Since I have so many problems on my car, that's why sometimes I try to make some jokes on this car to relief some frustrations.