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1984 Mercedes Key replacement

Certain repairs on these old Mercedes diesels are actually quite easy. As I remember, to replace the starter key tumbler, insert the starter key and turn to the unlock position, stick a paper clip in the small hole in the tumbler and the whole thing comes out. If the key is already in the #2 position it should be easy. Replacement parts can be found at reasonable prices on the internet or ebay. Keep your 300D as long as it runs. THey don’t make em like that anymore.

  1. If needing to change the cylinder, it could be because you are unable to turn the key to start any longer. If that is the case, the above method would not work.
  2. Even if you are able to turn to position 2, the above method still may not work.
  3. If you are unable to remove the tumbler, you will have to change the whole lock assembly. From the dealer that will be approximately $350 not including labor, but if you are mechanically inclined and internet savvy, you can do it (I did).
  4. You could get new tumbler or whole assembly from ebay or whatever for cheaper, but if you want to keep using just 1 key for doors and ignition, you will have to pay a locksmith anyways, so consider the total cost before going this route.

Careful!!! When I heard this call, I wanted to chime in and say WAAITT! I just had the same problem on my Chrysler Crossfire (made by Daimler in Germany). It turns out the Chrysler ignition is just a Mercedes part with a Chrysler sticker and insanely inflated price tag.

These ignitions are notorious for locking up internally - not the tumblers at all. It has to do with the steering wheel lock mechanism as you remove the key. There is a way to remove and modify the ignition yourself and fix this problem for good permanently - or if you’re not handy you can pay a dealer upwards of $500 for them to replace the ignition and wind up having the same problem return in a few months or years (random!).

Someone was nice enough to take pictures and illustrate the process below: