I hope some of you can help me here.

The car used to be so quiet that you cannot hear much when all the windows and doors are closed.

Suddenly, I can hear wind and road noise when I drive the car today. When going over hump, I can hear some rubbing noise from the door.

I notice the following:

1. The weather here has suddenly changed to about 12deg rather than 20+deg last week
2. The door close assist will close the door but then after a couple of seconds, I can hear a slight gas release sound, the door comes back out a bit. The door is still lock. I do not know this is always the case because I never pay too much attention to it. I might have to adjust the door latch because the door is not closing perfectly althought it is not bad. I do not think the door latch is the problem, even if it is, how can all the door latch has gone wrong suddenly.

Is there anything I need to pay attention to. What can be wrong?

Many thanks....

Michael

I would advise you check the weather-stripping. Can you more closely pinpoint where the sound is coming from?

And about your pneumatic door... It is supposed to close, pressurize, then release pressure, dependant on what, I don't know, but I know it's normal and your system sounds OK. Good luck.

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

The weather strip I have checked before as well. They are perfect. To be sure I actually used some rubber treatment oil on them. Compare to my W126, these rubber are like new.

The sound at first come from the rear passenger door but now they are from all doors.

It sounds like they are from the bottom part of the door.

I feel like I am writing a ghost story....

Michael

Michael my 93 500sel is doing the same thing, dealer said to have the closing assist replaced ie...another $500. I would like to know if there is a way to fix the closer in the door? anyone?

Do a search on "closing assist", it will give you lots of material.
The pump is activated by an electrical signal from the first catch on the door lock. It then runs untill it sees a signal from the door that it is closed, or untill the timeout circuit or the high pressure switch shuts it down! If it can not do the closing assist in three tries it disables that door or circuit. It can be reset by removing fuse#9 in the trunk. The hiss is an indication the pump is resetting the diaphram so it will be ready to "close assist " again. It is normal for the doors to pull in and then relax slightly as the pump turns off.