211 E class drivers door won't shut

[mickday]

I have an intermittent problem with the drivers door on my S211 E55K

Door opens OK as normal but sometimes when I pull the door closed it just bounces back open and does not close and will do the same when tried again. Locking mechanism appeared to be in open position as door was closing flush with bodywork but just not staying shut.

This has only happened on a couple of occasions both at night so have not really been able to look at the lock mechanism properly at the time. By fiddling with the handles (inside or out) a few times it will then close OK.

Car has key-less go and I have used this both times to unlock the car at the times I have had the problem (key in pocket and pull door handle)

Has anyone else experienced the same and perhaps have any ideas of what may be the problem

 

[AMGeed]

This thread could be useful Mick. A few idea there anyway.

http://www.mbclub.co.uk/forums/interior/23145-door-lock-bouncing-ml-w163.html

 

[evdok]

Dirty lock mechanism maybe, Spray WD40 that might help.

 

[mickday]

I have already tried spraying some silicone based lubricant into lock mechanism and this did not seem to make any difference as it has happened again since.

It has only happened a couple of time, both times at night typically

No problems with locking or unlocking but thanks for the suggestion AMGeed

 

[Will]

I reckon this issue is linked to the keyless go system. As you know when the door 'open' switch is activated on the reverse of the door handle, the door is unlocked and also opened/pushed away from the car as it disengages from the catch.

This issue happened once to me sometime last year - the door wouldn't latch when pushed closed. I cycled the keyless go open/closed and it then latched fine as normal and has been okay ever since.

I put it down (as a guess) to low voltage as a few days before this I'd been doing a few jobs on the car outside for several hours and ran the battery low. Hence I wondered if the motorised latch/unlatch had sort of stuck in the wrong position?

Just a thought

 

[mickday]

Thanks Will I think you may be onto something as I have only just recently been using the keyless entry option as I have replace the drivers door handle with a new one with working buttons.. I may experiment with remotely unlocking with the key and see if I can work out a pattern..

As I mentioned it has only happened twice anyway!

 

[mickday]

My problems with my door got worse on Saturday night after inadvertently opening my door with the keyless handle rather than the remote.
I ended up not being able to close my door at all. Luckily I was not too far from home when it happened so I drove home holding my door shut ready to take a look on Sunday.

So I removed the locking mechanism from the drivers door to see if I could work out what was wrong. Upon inspecting the mechanism it was visible that there was a cam which is driven by a motor that when engaged releases the door catch to open the door effectively pushing the door open. I suspected that this was not returning back to its original position thus preventing the door from latching closed after it had been opened.

I decided to dismantle the motor assembly to explore the mechanism further, it turned out that at the opposite end of the motor to the cam is a gear connected to a spring, similar to a clock main spring which when power is removed from the motor returns the motor and cam back to its original position allowing the door to be latched.

Here is a picture of the motor mechanism with the spring assembly removed

Here is a picture of the spring

All the components were quite dry and had very little grease left and the spring was also corroded. So I decided to clean up everything and apply some silicone grease to ensure that everything ran freely. Once reassembled I tested it manually several times to ensure that the spring would return the cam back to its original position.

So in the end all put back together and the problem solved... Top:bannana:

 

[Alps]

hi mick

only just saw this.

hopefully wont re-appear again, I had a similar problem and would only happen when the door in question was opened from the locked position.

the keyless locking relies on the spring and the spring had basically broken. if opened when doors are unlocked it would work fine.

I had to buy a new lock in the end

 

[mickday]

hi mick

only just saw this.

hopefully wont re-appear again, I had a similar problem and would only happen when the door in question was opened from the locked position.

the keyless locking relies on the spring and the spring had basically broken. if opened when doors are unlocked it would work fine.

I had to buy a new lock in the end

Hi Alps,

Yes mine behaved the same as your if the door was already unlocked then no problem, but if you opened the door from the locked position it would not latch afterwards.

I am hoping this will be a semi permanent fix as I very rarely use the handle to open the door from locked position (only when I forget that it is locked) I usually use the remote fob to unlock the car prior to opening the doors

 

[E270 Owner]

Always makes me smile when £1,000's of tech relies on one of the oldest mechanical principles.

 

[YDY]

All,

I've scoured the Internet, and this thread was the closest answer to the issue that everyone is seeing. After taking the latch out of my W211, and taking it apart, I was able to figure out what's going on here.
This answer only applies if your car has Keyless-Go, and the door fails to latch.

The door latch can be released three different ways. The internal door pull, the external door pull, or with Keyless-Go.

The external door pull and keyless-go door pull APPEAR to be the same, but they are actually very different things.
When the car is UNLOCKED, and you pull the door handle (internal or external), it's a mechanical lever or cable action that releases the door latch.
When the car is LOCKED, and you pull the outside door handle (with Keyless-Go), you're really actuating an electrical contact switch in the door handle. Assuming the key fob is in the proximity of the car, that contact switch causes a motor to spin and rotate a gear 180 degrees. The gear has a CAM on it that moves a lever to release the latch. After the door releases, NORMALLY the gear/CAM unwinds back to it's home position. (When activated it winds up a spring which then causes the gear/CAM to unwind when power is removed from the motor).

The problem is that if the CAM rotates 180 degrees and then "sticks", the door will NOT latch. It's just like as if you held the internal door pull in the fully extended position.

My latch was stuck in the fully engaged position. I applied 12V to the motor manually a few times to simulate activating Keyless-Go, and it finally unwound like it it needed to. After it unwound, the latch started to work as expected.

If the spring is broken, the CAM will never return to home position, and the door will not latch. You'll need replace the latch or spring.
In my case, the spring was fine. I added an extra bit of preload to the spring, lubricated everything, reassembled and reinstalled. The latch works just fine now.

Mickday's photos above show the Keyless-Go motor, spring and the white gear with the CAM on it.

ydy