Hello everyone new to the forum. I'm a 35 year retired Master Tech in gas and diesel vehicles both large and small but I'm stumped with my daughters 1997 E320. We thought the key had went south because it hasn't recognized the key in the ignition for some time but it started and was driven daily. Well we gambled and ordered a new key from MB. We picked the key from the dealer and tried the new key,everything else worked perfectly but the ignition still won't turn..........do we possibly have an ignition lock cylinder with worn out tumblers or the switch part that's faulty??? Sorry for being long winded but sometimes more is better,any and all help will be appreciated . Thank You in advance

 

I have a '97 and have had some key problems, but I don't understand the comment in bold above. If the engine started, the car was recognizing the key. If the key was not recognized, the engine would have cranked but it would not have started. The car is old enough that the ignition lock cylinder may be going bad. If the keys will not turn it will be difficult to replace the cylinder as it has to be turned to run to allow it's normal removal. Perhaps the steering wheel lock has become stuck, keeping the key from turning. A dealer or good indi that is familiar with this set up may be able to use your new key and get the cylinder to turn enough to replace it. The new key has a better chance of turning the worn cylinder than the old worn key, in my opinion. If they can get it to turn you can buy a new cylinder to fit your old keys for about $80, plus the installation labor.