I need a little assistance from someone who has had a similiar problem. Took car to get front end aligned after tie rod replacement. Indy started car a couple times then said something was wrong with key switch.
Here it is; when key is turned to glow, no prob, glows properly. When turned to start position, key turns farther than normal and does not engage starter. Wife called me on phone, stuck at Indy.
I talked to indy and said, turn key to run postion and jump across start solenoid. He did this and my wife got home.
My question is, is this the key tumblers or is the complete assy going to have to be removed from steering column?
Sorry for the long saga explaining it.
Thanks in advance. I'm going to be out fiddling with it.

When similar happened to me in other cars, it is because the ignition key housing is rotating. That was in older 60's cars with a simple screw-in dash switch. Your 83 240D is likely the same as my 84 300D, with the key switch in an extension tube off the steering column. I took mine apart to fix a jamming key, due to a broken spring detent in the rear. As I recall, the key innards are held in by a locking wire spring that pops in a little hole in the housing. You must get the key in a certain position to push the wire free of the hole to pull the innards out. You can find instructions and photos here in a search.

Sounds like you can at least turn your key, that is good.

Here is a Diesel Giant pictorial on the switch an some good pictures. he is grinding off the lock pin which you won`t have to do.

http://www.dieselgiant.com/repairignitionlock.htm

Iam thinking your problem could be either the tumbler where it turns the lock housing, the pis are worn, or it is in the ignition switch on the rear of the lock housing.
here is a write up I did when I replaced mine. I have done this 3 times so far.
I jest replaced everything and was done with it. If you need to replace the tumbler, be sure to buy it from the dealer, and it will be the correct one for your VIN #. if you decide to pick up one for another car, you will have 2 keys, one for the door and one for the ignition. loose the ign key and there is no way to get one from the dealer as they go by vin#. something to think about.

Ignition cylinder problem...

Hope this helps.

Charlie

__________________
there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

Bill and Charlie; your both helpful. Yes; I can still rotate key with some manipulation. It was hard to get to turn. For some reason the key wants to turn past the start position. I used the wire trick and unscrewed the black housing around key tumblers and pulled it out. Now, I'm trying to determine if its the tumblers that are messed up or what. Seems like with the key being able to go past the start position; is that bad tumblers or in the actual ign switch mounted on back of housing.

Use a slot screwdriver and push in on the spring loaded Tang at the bottom of the holeof the housing with the Tumbler removed. push down on the Tang and turn to the right. the GP light should light up, and turning a bit farther, the engine should start. Iam thinking if it is turning farther and not starting, then it might be in the lock assembly.

Do you feel resistance with a spring? you should be able to turn against the spring into the start position then it will go back to the run position as you let go.

Charlie

__________________
there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

Thanks Charlie; I'll try that today. I thought the tumblers were going to be the problem but I'm going to do the screwdriver method and see what happens. I really appreciate the help.
Its ironic; I just replaced a tie-rod end and sent to indy for alignment; the power steering pump had been leaking so I replaced it, and the alternator was making noise so I replaced it; then the wife gets stuck because ignition switch. Does it ever end? Oh I know; its 29 years old.
Thanks again.