ignition problem, which part?
 

I've got a 1987 300 sdl. I went to the store today and when I came out, it would not start. Key turns, glows, but will not turn to start. After several attempts, and trying letting it roll, and locking the steering wheel, I called my boss to come get me. I went back to the store about an hour later and tried again, but to no avail. After supper I started searching the archives. Went back to the store and removed the lock cylinder. I was then able to start the car by turning the switch with a pair of needle nose pliers. Switch turned easily, although I did have to move it some with the pliers to line it up properly for the a/c to work. Took it to my office around the corner. Shut it down and restarted it with the pliers with no issues. Put the lock cylinder back in and tried it and no go, it will not turn to start position. So, my question is, do I need a new lock cylinder or a new switch, or a new lock assembly? Thanks

Sounds like the ignition lock cylinder, if I understand correctly what you are saying. The ignition switch should turn to glow, then to start....once. Then it needs to return to the off position in order to enable it to return to start.

The local MB dealer priced a new cylinder keyed to the original key for $80. The just need your VIN #, may take a few weeks. It's done in Dallas Texas.

Please explain in more detail. The lock cylinder turns to which position.........and then it stops...........and will not go all the way to the #3 position (start)???

Or does the keyswitch work properly and the engine cranks and won't start?

More details are necessary for a proper diagnosis.

Very similar situation as posted by pandadan. The key turns freely to all positions. It turned to position 1?, where I can insert paper clip and remove lock cylinder. It turned to position 2?, where glow plugs come on. But, when turning to start position there is no spring resistance feeling and no turning of starter. With the lock cylinder removed, I could insert a pair of needle nose pliers into the tangs(indents where the lock cylinder makes contact) and start the car and drive it and it functions completely normal, after turning back slightly to left to get it aligned in run position. However, now I have a new problem. I decided to try to use a screwdriver instead of the needle nose pliers and broke off the piece that the lock cylinder lines up next to. I will be ordering a new ignition lock housing and a new lock cylinder. The housing comes with a new switch. Ordering the cylinder in case it was the original problem. Will try original cylinder first to try to avoid having key for ignition and key for doors.

If you ordered a new key & cylinder from the dealer, they should be already matched to the original using the VIN as a reference. This will eliminate reusing old parts and possibly introducing another problem.

See post under pandadan for the problem and the solution.