Mercedes-Benz Forum banner

Drivers door handle not opening door

11K views 10 replies 5 participants last post by  rlambert911 
#1 ·
Hi All,

I've just bought a 1994 S500 Coupe which has been standing around outside unused for the last couple of years. It is a sound car with only 2 owners and 84,000 miles and the owner stopped using it due to the engine cutting out when hot. I think this issue is related to the ignition module so that is my next task once I have got the other issues resolved.

So to the door problem...

The soft close and the central locking works ok, and I can unlock the car with the key or the remote. The button on the door pops up as it should and the exterior handle moves in and out freely but it doesn't open the door, the only way I can open it is by using the inside handle.

The passenger door works as it should.

I have sprayed lots of WD40 into the lock and I removed the torx bolt on the inside of the door to release the handle mechanism so I could spray inside but it hasn't helped.

The door was opening correctly so the problem has only occurred whilst parked up.

Any ideas please?

Thanks Richard
 
See less See more
#2 ·
So I'm guessing no one else has had this problem?

I'm going to take the door panel off to see if I can spot anything wrong.

Is the connection between the door handle and the lock electrical or mechanical ?

Thanks
 
#3 ·
I have the same but on passenger front door. When I unlock door, all four button pops up but passenger door doesn't go open from outside. Only sometimes. Sometimes it works and sometimes not. Just now it didn't work, I tried to unlock with the button on center console and it unlocked.
 
#4 ·
rlambert: The connection is mechanical and fully accessible from the outside of the door. I wouldn't crack open the inside of the door unless you're sure you need access to the entire latch mechanism.

The way the exterior handle works:
- The handle is attached to a linkage that is parallel with the direction the handle moves (in and out). At the end of the linkage is a ball.
- That ball slides into a circular socket that is part of the lack mechanism.
- Pulling the door handle pulls the linkage, pulls the ball, pulls the socket, and that releases the latch
- The way this is supposed to be assembled is that front of the door handle is inserted into the door, you push the rest of the handle into the door, and then slide the handle assembly towards the rear of the car. Pulling the handle assembly towards the rear of the car is what slides the ball into the socket.

It sounds to me like either somehow the ball missed the socket, or either ball or socket is broken. Small chance the linkage post-socket is broken but pretty unlikely.

PetrFin: Your situation sounds like a broken lock rod or actuator. I just fixed an identical situation in my car, which was broken lock rod. What was happening in my car was that while the lock rod was broken in two, because the space the rod operates in is fairly tight, the rod stays upright and operating in the same general "column" of space. Randomly it will make contact with the other half of the broken lock rod and push the lock button up. If the lock button never goes down with the power locks, then this is likely your situation since even if the broken lock is perfectly aligned, it can't pull the other half with it. It's only able to push. If sometimes the door lock button goes down with the power locks, then it's probably the acuator.
 
#6 ·
Thank you for you description, that is very helpful. I will have another look at the lock, I'll remove the securing bolt and jiggle it around a bit.... and see if I can relocate the ball.
 
#5 ·
I have had similar intermittent problems with the S500. The driver's door and the passenger door will sometimes decide not to work and I have to open from the inside. I sprayed the hell out of everything with silicone spray and it seemed to help.
 
#7 ·
We'll I've had another look at it and it's not the handle, that is working ok and the ball is locating ok. The problem is in the linkage to the lock as if I pull directly on the linkage it moves ok but doesn't open the door.

The internal handle still opens the door ok.

I've sprayed loads of penetrating fluid on the mechanism and will check it again but it looks like I need to take the lock mechanism out next.
 
#9 ·
Well, if you're central locking works properly, the handle is working properly, and the linkage attached to the socket is moving but not opening the door... then you've got a latch issue.

When the latch is in a closed and locked state, the linkage attached to the socket can still move but it just doesn't actuate anything. There are a few inputs into the locking lever (external key, lock button at top of door, lock rod to central locking actuator) but it all sums up to the same thing. Something in the linkage after the locking lever is hosed up.

Pictures always help. I happen to have a driver side coupe door latch at hand. I bought it when I was having my own door lock/window drop issues but didn't end up needing to use it.

First picture shows the latch in an unlocked state. The red circle is where the lock rods connect, and you can see the rest of the locking lever attached to that area. The red bushing at the top rotates with the key to push/pull the lever. Lock rods obviously push/pull the lever as well. As far as the locking mechanism itself, the locking lever actuates the smaller lever in the blue circle. That smaller lever is what locks the latch, or at least actuates everything else inside the that latch that locks it. Cue the second picture.

Second picture shows the door latch in a locked state. You can see the difference in position of both levers. What I suspect is that you've got an issue with the lever in the blue circle. That lever has a little spring that manages it's position. The spring pushes the lever towards the unlocked position when the big locking lever isn't pushing it into a locked position.

I suspect that level is the next likely suspect for what's broken. The latch assembly overall is really solid. I would be really surprised if any of those levers, etc were broken. But that little spring on the little lever in the blue circle. That could be broken. You'll need to loosen up the latch so you can get a finger up there to see if you can manipulate it and see if the spring is still engaged.

If that's not it... you're beyond my knowledge for sure.
 

Attachments

#11 · (Edited)
Ok it's fixed.

I had to get to the lock mechanism, so the door panel came off and I unbolted the lock. Once it was free I was able to access the lock via the various holes in the door.

It was nivefiveone's post which helped, specifically the pictures. If you look at the blue circle in the 2nd picture, my mechanism was in this position even when the door was locked or unlocked.

All I had to do was push the mechanism slightly and it sprung open as per picture one. I was surprised how little effort it took to free it and once freed it worked fine.

I reinstalled the mechanism and now have a working door handle.

Only issue now is the key doesn't operate the central locking ! Although the remote does so I'm not that worried.

Cheers
Richard
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top