Door lock hell! (long)
 

Greetings all,
Working on a '89 420 SEL this weekend and had the following nightmare:
Drivers side lock inop with any of the keys. Passenger side door lock was operational and locked entire system beautifully. My idea was to simply switch the handles.
Wrong.
Inside the door panels, the door handle is removed by slightly loosening a set screw on the leading edge of the handle mechanism through an access hole on the inner door's metal skin. Then the lock/handle assembly has a long thin rod which is connected from the back of the keyhole to the assembly carrying various linkages to the door latch and the vacum system. In order to disconnect the door handle I had to pry a small plastic drum which fit inside a keyhole to rorate, then release the lock/handle assembly.
BOTH of these plastic pieces snapped off at this keyhole junction when carefully prying them up.
I tried to drill a hole in the remaining plastic and thread some decent gauge wire through to connect the plastic drum to the linkage, but no dice.
I then tried to drop the entire striker plate/latch assembly from the door to access and replace these plastic pieces...and wow is that a pain.
Any advice on how to get these striker/latch mechanisms out of the doors?
As far as I could tell, the Window regulator bar furthest to the rear of the door, completely blocked getting it out of the door for servicing.
Finally, I have come to the conclusion that my problem did lie in the door handles...it is indeed somewhere within the latch mechanism.
Any help greatly appreciated!

I'm not sure what you have now but I imagine that you had a tumbler problem to begin with. If you can get the key to turn the door handle can be removed without taking the door panel off. When the tumbler won't go one must get the 90deg rotation of the latch by a combination of turning the whole handle and the turning thelatch once loosened.

The tumblers come apart very simply once the handle is off and the tumbler pack can be mmoved from handle to handle. Once you are that far though it becomes plain why the tumbler quit and its easily repaired without any other parts. The tumblers wind up not being moved far enough due to wear. Just throw out the offending tumblers or file them down till they fit.

Steve -

My driver's side door lock isn't locking on my 300E. The key won't turn in the lock - it gets stuck. Passenger side works perfectly. I'm assuming this is due to wear. The driver's side will lock occasionally if I play with it long enough.

Are you saying that I can simply remove the tumbler/lock mechanism from each handle and swap them? This won't affect the alarm or anything?

Can I get a new tumbler? Any info much appreciated - thanks!!

you can switch them but i recall there is an issue with positioning the drain hole correctly. it will be upside down and cause problems later on. you can get the lock with a key for $150 at your dealer...

hmm...maybe I will try and fix the driver's side tumbler then. I am assuming it is the tumbler as the key fits in but it does not turn smoothly if at all sometimes. You can remove the tumber through an access in the rear of the door correct? (area normally hidden when door closed)..?

Perhaps you could get a new lock at a junkyard and then take it it a locksmith to have it made to fit your key.

This should cost less than $150, but I'd call the locksmith first. Mercedes keys and locks are not standard after 1990.

There is certainly nothing in a doorlock that should cost that much.

I don't know if we have ever re-keyed a 124 door lock cylinder, but I imagine we have. The door handles and probably the separate tumbler section on 124 style handles, comes apart. it is not in the MB manual as there are no sub components available.

The way to fix these problems it to disaasemble the tumbler body and file down the worn tumblers (or remove them - there are plenty) untill the key makes them flush. When disassembled the needs will be obvious.

Thanks Steve, that's what I intend to do.

To remove the tumbler - I access it from the 'rear' panel of the door right? (the portion normally hidden when door is closed). There's a large black rubber grommet there that I remove to get access to it, correct? Any tips? I'll be tackling the job tonight or tomorrow...thx!!!