Buzzing from boot lol

[Chris_c200]

Hey guys ive got sum annoying buzzing sound in the boot, ive been told its my central locking pump. I turn the car on and it will hum on and off at about two second intervals for around 5minutes. Anybody had this problem before? weird huh.

Also, in my engine bay there is a white vacum line which isnt attached to anything. Its behind the engine. Anyone know where this goes?

My cars a 1994 c280.

Thanks in advance

[FRieD.eGG]

I have your same problem. My mechanic said I may have a vacuum leak somewhere and the buzz is caused by the vacuum pump. I will drop my car and let it fix next week when I'm out of town. Hope it can be fixed. But the mechanic said it should be fix as it will slowly caused the vacuum pump to die and costs a few hundreds (USD) to buy a new one.

[Chris_c200]

Hey man please let me know how you get on? Yea a new pump will be expensive as!

[OzC36]

The white vacuum line goes to the connection on the aft, inboard, lower side of the throttle body (gas actuator).

The buzzing noise you describe does sound like your vacuum pump working overtime due to a vacuum leak.

[Chris_c200]

Thanks OzC36, I managed to locate and reconnect that vacuum line. As for the vacuum pump.. Got any ideas as to where I should begin my search for the leak? The rear headrests go down easily so I can count that out.

[V1Dreamer]

your vacc pump should be underneath your rear passenger side seat. just pull the bench seat out via the little levers at the lower front section of your seat towards the doors.

from there, you should be able to locate the main vaccume source line, there should be a rubber elbow there. ive seen those either come off, or just old and crusty.

test the source tube with a vaccume tester. or just suck on the tube and it should hold vaccume. if it does, go no further. your pump has taken a dump.

the pump internally has a vaccume tank, which builds up and holds a specific vaccume in order for you to lock and or unlock your car without running it.

if you find that the pump is the source of the leak. before you go and spend some bucks on a new one, you should open up the pump and see if the hose inside is still connected and or in good shape. (no splits/cracks).

i hope i was of some assistance.
good luck.

[Chris_c200]

The object which is making the noise is on the right hand side of the boot looking in, Its surrounded by foam and has two lines connected to it. Is this not the vacuum pump? Thanks for your help mate ill look under my seat now

[OzC36]

Mercedes use Vacuum as muscle power to actuate a wide range of devices including rear-seat head rests, a/c vents, auto-transmission control, dipping headlights, central locking etc.

If any of your vacuum operated systems is not working correctly, the lines and connections associated with that system are a good place to start.

On my car, I believe that the white and gray lines are vacuum supply, green for a/c control, purple for dipping headlights, red for auto transmission. I could be wrong and invite anyone with better knowledge to chip in here. The rest I don't know.

The main problems seem to be lines disconnected accidentally when maintenance or cleaning is carried out. Other causes are cracked or damaged connection components. The lines are generally fairly robust but can also be cut, split or cracked or chewed by naughty critters such as rats.

Good luck!