W123 Steering Column Lock Reliability Concern/Fix
 

Last Monday, Lilly's ('84 300D) steering column lock failed. Unable to pick the lock I called a locksmith, whose picking attempts were also unsucessful. Ultimately, the locksmith used a Dremel tool with an abrasive cut-off disk to cut the hardened face of the lock into quarters so that it could be removed and expose the Zamak lock cylinder so that it could then be drilled out. Even after removing the pieces of the cylinder, the column still could not be turned and further 'surgery' was needed.

As it turned out, the key part of the mechanism had not failed. The real problem was caused by a broken part in the assembly which closes the warning circuit switch when the key is inserted into the ignition. This piece broke loose (probably due to age), blocking the cylinder from rotating far enough to pull the locking pin out of the steering column or making the necessary electrical contacts to start the engine. 3.5 hours and $214.56 after the locksmith arrived, I had a running car sporting a pile of metal debris and broken cut-off disks on the floormat.

Achtung!! Vorsicht!!!
It's been said before but I'll repeat: When this part fails you are a captive audience until the locking assembly has been destroyed and extracted from the steering column. Fortunately for me, we have extra vehicles to use and SWMBO's car was in a relatively secure location. Even so, this exercise was a huge inconvience but, it was nothing compared to what it would have been like had this happened at a Dennys parking lot in Hearne, TX or a truck stop in Santa Rosa, NM.

Yesterday, I pulled a replacement column lock assembly from one of my parts cars and noted that the column locking pin only moves about 1/4" to engage and lock the steering column. Right then I decided to disable the column locking mechanism on all my cars by grinding-down the locking pin far enough so that it cannot engage the steering column. I may be compromising an anti-theft feature of the vehicle but, at least if the lock assembly fails, I can hot-wire the car to get it running and move it to a safer or more convenient location for repair.

I had never contemplated the hot-wiring of a 123, but I suppose that one would need to disconnect the shut-off actuator in order for the engine to run with the switch in the "off" position. Disabling the steering lock certainly seems like a reasonable idea. It could solve another problem that I was facing-nothing to do this afternoon.