Key Suddenly Won't Work
 

One of the keys I've used in the car ('92 300D Turbo) for the past 22 years suddenly decided to stop working yesterday. My wife used it to drive the car in the morning and when she came back to it several hours later, it wouldn't work in the lock. Fortunately, she had the other key with her, which did work.

It's the old-timey key, with the black rubber fob around the handle (if that's what it's called), and it sits in (but is easily popped out of) a dedicated leather case it came with when the car was new .

Any thoughts?

Time for a New Steel (Mercedes ONLY ) Key
 

Anything other than the MB Steel Keys will allow metallic shaving to be created
and enter/shorten the lifespan of the Lock Cylinder's "Leaves".

The best deal is with a MBCA membership,And Purchase from the Classic Center
in California.

This gentleman can help you.
Thomas Hansen@MBUSA.com
(949) 5984842

Y'all might also think about getting a New Ignition Lock Cylinder
(That comes with a New Key That matches all your other locks by VIN #)
After 22 years y'all might be looking at ignition lock cylinder wear also.

The reason I suggest Prophylactic replacement of the Ignition cylinder is that
If it wears to the point of "Locking Up" and you can't get it to Position #2 to
be able to R+R the cylinder... You are "Up the Creek".
Much more complicated and expensive procedure.

I.E. :

http://www.peachparts.com/shopforum/...turn-help.html

http://www.peachparts.com/shopforum/...-r-r-w124.html

http://www.peachparts.com/shopforum/...iesel-gas.html

You can call BAUM Tools in Florida and get this tool kit that has Lock cylinder removal tools for
about $20.00.
(2nd Picture, Bottom Tool)
Along with Tools for Instrument cluster "Pulling" and Radio removal keys.
(800)949 6657

Owners who are Machine-ist DIY-ers have sucessfully made their own tools ,But It was just too
easy and cheap for me to get them from BAUM.

lock
 

I once read on a forum a way to repair them by removing the barrel cylinder and as you look at the barrel and the tumblers , to find the ones that are high ,and remove just the ofending ones . I have looked for ages to find the post again and i cannot. I did my passengers side and it works now. If you can get the lock barrel out, you would get it put right by a locksmith.You can file them if not to bad.They wear over time and then the tumbler wont clear the slots inside of the barrel as you try to turn the key.You can try WD40 if you have it over there or Plus Gass before you remove it first Pelican Parts will show you how to remove the barrel.

lock
 

This may help ,i dont know. You will have to put this in Google
Guide to dissemble and fix lock barrel on 190e.