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Is this normal?

2K views 12 replies 8 participants last post by  n5160u 
#1 ·
My 2005 E500 sits in our garage and every morning as soon as I open the driver door, I hear an odd sound. It appears to be coming from under the hood on the passenger side. Is sounds like a motor or compressor starting up and humming/vibrating for about 3-4 seconds. Does this have something to do with the airmatic suspension? braking system? :confused:
 
#2 ·
The SBC (braking system) does make noise when first entring the car. There are other things that beep, etc, but I haven't figured out what they are. One day I was programming a new garage door opener and had the ignition on for a few minutes -- the car sounded like R2D2 from Star Wars.

BTW, there is a TSB out for making the SBC more quiet, but the service isn't automatically done -- the customer has to complain about it first.

Regards,
paul...
 
#3 ·
Yes, that's the SBC system.

ANother related question, my car in addition to the SBC sound makes another sound which is like an air release sound. I have a non-4matic E320 wagon and every now and then I hear it either fill with air or release air, I cannot tell which. Do all these cars come with some sort of self-leveling suspension or something like that?
 
#4 ·
The wagons have an air assisted auto leveling rear suspension.
 
#5 ·
n5160u said:
The wagons have an air assisted auto leveling rear suspension.
No kidding? Thanks. That explains it. Have any idea where I can find more info about this feature?
 
#6 · (Edited)
paulv said:
The SBC (braking system) does make noise when first entring the car.

Regards,
paul...
I hear the noise as well. Next question is why the SBC makes the noise at that time? Why would opening a door get the braking system excited?
 
#7 ·
Case1906 said:
I hear the noise as well. Next question is why the SBC makes the noice at that time? Why would opening a door get the braking system excited?
Isn't it obvious, the car is sleeping (SBC and most of electronic equipment) when not used. Opening doors is an early indication that the car will be used and the car then gets ready for a run.

Maintaining the brake pressure all the time could make the battery run flat and would unnecessarily wear the pump. SBC not only pumps up the brake pressure but also checks that pads are properly close to the rotors (which is why you have to be really careful with brake maintenance with this car) and likely some other stuff too.

SBC and Airmatic (or rear self levelling on a wagon that is not equipped with "full" Airmatic) both wake up when the door is opened.

The wagon rear self levelling system is pretty much the same as a normal Airmatic except that it does not come with air springs on the front and if I remember right, it does not have adaptive shocks (should have checked from EPC).
 
#8 ·
Kodabear said:
I hear an odd sound. ... Is sounds like a motor or compressor starting up and humming/vibrating for about 3-4 seconds. Does this have something to do with the airmatic suspension? braking system? :confused:
Yep, there are quite a few systems in the car that purr on. If you park and lock the car it will make various noises for a while shutting down the systems. I have not clocked it up but I figure it takes a minute or two for it to "go to sleep."

It is nothing to worry about.
 
#12 ·
johnamoss said:
In the old days the only thing to shut down was the engine. Now, we have to shutdown our Microsoft E-Class!
__________________
'87 300E: sold after 11years @ 230k & still on the road somewhere in rural Tennessee.
Yes, but you did not post this message with your Commodore 64 even if it works "better" than your MAC/PC? Of course I would hope my Microsoft (PC or E-class) had less bugs.
 
#13 ·
johnamoss said:
In the old days the only thing to shut down was the engine. Now, we have to shutdown our Microsoft E-Class!
If the car was really Microsoft it would spend all its time in the shop and the SA would lie and collect your money promising upgrades to fix things that aren't broke while the fixes in reality cause more problems......
Oh.. wait a minute, now you said the car just quit running and your nav screen turned blue?
 
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