OK I am stuck. I am trying to remove the key and cylinder from a 1987 300 SDL. I have found some threads on this and I am still confused. I just got the car and found out from the previous owner that he removed all but one of the tumblers. I spent over an hour trying to get the key to turn. I finally got the key to work, but with a lot of force. I need to remove the key. What position do I need to insert a pin to unlock? How far does the pin go in. Should I be able to feel a spring tension? A lot of questions, but I am in a bind,

Im not sure of the difference from a w123 to an 300sd but when i removed my key cylinder in my 300d parts car last night i turned the key to the first position, then inserted a paper clip and proceeded to turn the black ring with some force, not great, but some counterclockwise to unscrew it. i had to wiggle the paper clip a little to disengage the lock pin. i didnt feel or hear any spring tension the only indication was that the black metal ring started to unscrew i also sprayed a little shot of pb blaster inside of the black metal ring to help it turn easier. but, i would not suggest spraying it in the keyhole.

W123 and W126 diesels used the same ignition lock assembly.

The tumbler is not your problem. You need to replace the lock assembly which wears internally until it will no longer pull a locking pin from the steering lock. As long as the tumbler works with the key, the tumbler should be sufficient to work in a new lock assembly. If you have concerns, replace the tumbler with the lock assembly.

There are threads here that suggest turning the key while using a random orbital sander or other vibratory device on the inserted key in order to goad the assembly into releasing the steering lock. I have not done this, but it couldn't hurt to try if you need to.

The tumbler/key must be in the position 1 (first detent) to allow the pin to be inserted in the hole. You should be able to 'feel' the release of the catch that will allow the ignition ring to unscrew. It takes a bit of pressure as I recall. I can't remember if you need to keep the release engaged for the whole time you are unscrewing the ring or not.

__________________
mjk

'84 300SD 119KMi (Liesl der Diesel)
'84 300D 326KMi when the oil left (former parts car)
'82 300SD 253KMi (new parts car)

I tried and tried to get a pin to release the lock but I had no luck at all. I finally coated the key with never seeze and for now it is working good. I still cannot understand why the lock will not release. I measured and the pin I was using would go in about 1.25 inches but I did not feel a release. I will try again to get the cylinder out. It has been a PITA. PS I was using a ss tig wire that was rigid. Any suggestions or thoughts? Thanks Jack

It helps to file a chisel point on the wire so that the points are on the outside and the bevel going to the inside. A small thing, but it helps the wire get into the clip. Once behind the clip, the tumbler comes right out.

There's two parts to the tumbler: 1) the top (visible) and guts; and 2) the outer frame. The wire should slide in about 3/8ths of an inch at the edge of the top before it hits the hole in the outer frame. What you might try doing is moving the key back and forth slightly to align the slot in the top with this hole. If you shine a light you should see the hole at the bottom of the slot when it's aligned properly. The wire should slide in another quarter inch to fully retract the pin. As the wire slides in it pulls a pin into the tumbler frame. It doesn't do a sudden release. The farther the wire slides in, the farther the pin retracts until the wire bottoms out a quarter inch in. You might try jiggling the key while pushing the wire to provide a little wiggle room for the pin to retract.

Just to note, the hole is only exposed when the key is in position 1, which is about 90 degrees from position 0 (remove/insert key position).

Once the pin is retracted (wire is fully inserted) you'll be able to turn the outer ring in a counterclockwise direction. The ring secures the tumbler in place on the steering lock assembly. Once the ring is spun off, the tumbler can be removed.

__________________
mjk

'84 300SD 119KMi (Liesl der Diesel)
'84 300D 326KMi when the oil left (former parts car)
'82 300SD 253KMi (new parts car)