mcleantmw

Not sure how to describe this but there's a small thumping noise, like an air pump or some other type pump unit, that I get periodically from my engine compartment. It's coming from some type of unit on the left front next to the engine.......some type of pumping unit. It occurs when I've been driving for a while and doesn't affect the performance of my car but it's annoying when I come to a stop lite. It hasn't made the noise when I've taken the car into my MB service department but my warranty expires in Jan 09 and I'd like to get the unit replaced before then. Anyone have any experience which component makes this thumping noise and is it a symptom it's going to fail? I only have 57,000 miles on my E500.

Benz-O-Rama

SBC pump. Totally normal.

Try this...

With the car running and in park, pump the brakes 3 times and hold it to the floor on the 4th. This should activate your SBC pump. Same sound?

konigstiger

Front left:
If you have the Sport Package (Airmatic) up to VIN A735291, and you hear a knocking and/or rumbling type noise from the front left of vehicle this is the Airmatic compressor moving within its mounting bracket. A modified bracket should be installed. Mention DTB P-B-32.22/32 AUG05.

Front right:
As mentioned it is most likely the SBC and the noise is normal however, it can be substantially reduced by installing a modified suction hose if not already equipped. Mention P-B-42.46/27e NOV07.

NO_WUR_E

There are threads about SBC. Yes, I get the same noise. Normal, BUT very annoying. It happened to me when I took my car in. My service advisor, did confirm that it's SBC.

gnma

Take it back to your SA, and give them the info. above from Konigstiger. It works - it substantially reduces the SBC sound.

xr650rguy

March 2006 build date. E500 RWD
Is this the kind of noise that you sort of hear yet sort of "feel", as well?

When my car is hot (after driving a bit), I'll stop in traffic or whatever.
When I roll forward, I can feel/hear a thump. It's barely perceivable.


It sounds like if the shock was loose in it's mount slightly. just a little thump.
Passengers don't notice it, but I do

usually occurs when the car is hot and I'm rolling very slowly. Bumps don't seem to influence or change it, so I'm ruling out airmatic.

Sounds like something is just a bit loose. Maybe like a pump that's engaging (which I can't hear), but when it torques over the mount bumps a little.

Any ideas?

mcleantmw

No, the noise from my vehicle's left front is a continual thumping noise that's heard when coming to a stop.......only after the vehicle has been running at high speed for awhile. As previously mentioned, I'm going to have my dealer check out the Airmatic pump bracket.

mcleantmw

I had my 2003 E500 into the MB Dealer yesterday for the "A" Service. I asked them to pursue the noise issue for both the AIRMATIC unit and the SBC unit per the Service Campaign data you provided. My Service Rep has ordered the parts for these two repairs and will have them installed on Monday. I also gave his a list of some other Service Campaign items that you had listed on the Recall Posting that included my vehicle's VIN and his response at the end of the day was: The MB policy is that a customer can't just list these items but has to identify a specific problem that needs to be corrected like I did with the AIRMATIC and SBC units' noise. He said MBUSA won't pay the dealer for the work. Of course, the customer would never be able to ID some of the Service Campaign issues, like the one with the drain hoses being clogged in the wheels. Is my Service Rep correct about the MBUSA policy on getting the Service Campaign items looked into?

konigstiger

Not every vehicle listed in the VIN range may be included in the campaign. VMI (Vehicle Master Inquiry) must always be checked before performing campaigns to verify that the campaign is required on a specific vehicle. VMI always overrides the bulletin in reference to a specific vehicle’s inclusion in a particular campaign. Furthermore, Recall and Service Campaigns do not expire - even out of warranty.

Therefore, your SA must check your VIN in VMI and if it is included in any campaign, the dealership must perform the work - MBUSA will always pay for Recall and Service Campaign work if included.

mcleantmw

Well, they performed the two Service Campaigns today at my MB Dealer. The one did tone down the SBC noise. But the AIRMATIC still makes the background thumping noise after they installed the new bracket. My guess is that the AIRMATIC unit itself is making the noise and I'll just have to live with it. Just hope if it fails, it does it before my CPO Extended Warranty expires in Jan 2010!

MBNUT1

I don't think that it is the airmatic. My nonairmatic E350 4matic makes a thumping noise in the rear when I am sitting at a stop after driving it.