Door lock cylinder repair

[66andBlue]

After a short trip with my 230SL I noticed that the key would not turn in the driver side door lock. In case it happens to you here are a few tips for a possible repair provided you have some spare parts from another lock cylinder.
1. Remove the handle, unscrew the locking arm (or stem), then remove the locking clip and the parts come apart. See first photo.
Careful, do not remove the key while doing this!
In my case one of the five tumblers was broken and the bits prevented the cylinder from rotating.
2. To replace a tumbler slowly pull out the key while using your index finger and thumb to press down on the spring loaded tumblers. Two of them point down and three point up. Usually there is enough old grease and gum present to prevent the tiny springs from firing these tumblers into orbit. But if you are a neat guy who doesn't want to get dirty fingers you may have washed the cylinder clean with carb or brake spray cleaner and then it is a distinct possibility that they'll fly off.
3. The reason for the broken tumbler was my original key whose teeth are now no longer sharp and pointed. As shown in the second photo this causes the tumblers not to retract completely and you have to wiggle it up and down and pull away a tiny bit. By trying to rotate the cylinder with a bit of force I obviously broke one of them. Fortunately my spare key is still good and when inserted all tumblers are flush.
4. Even if you have spare tumbler of the correct size you may have to file the "nose" a bit in order to insert it correctly into the slot.

I'll put this into the technical manual also.

[Jordan]

Thanks Alfred.  Perfect timing as this is one of my next tasks as the key in my drivers side door lock will also not turn.  Although the key would not turn in your lock were you still able to lock the door with the door latch?  My latch will not lock either, I can't push it to the other side.  So it is either a door handle problem or a door lock problem.  Thanks for the great info and pictures.

[ja17]

A little graphite lube in all the locks, could save you from an expensive repair in the future. Especially ignition lock assemblies should be graphite lubed every so often. Original keys are cut in steel and do not wear as fast as the brass generic blanks. Often times The Classic Center can order you a new set of original keys for your car. I recently ordered a new original ignition key for a 190SL from The Classic Center.  It was less than $10.00 and included shipping!

[Rolf-Dieter ✝︎]

Thanks Alfred, I had mine (driver side) fixed at Mercedes Benz, the bill was $220- LOL the mechanic found one of the horizontal connecting rods missing (must have been left out during the restoration) he fabricated a new one. I guess I paid for labour more then anything else.

My passenger side door (I can lock it from the inside only) and glove box still needs fixing, thanks Joe for the graphite lube tip makes a lot of sense. I will properly also order a spare key set from Tom at the classic centre (hate to hot wire the car should I ever loose my keys).

If the graphite does not work I'll go Alfred's route this winter