It is in the FSM in the same section as removing the steering lock. Basically the procedure is

0. take off the silvery o-ring.

1. insert key and turn to position 1 (this releases a "detent" or something, I think that's what they called it).

2. push/wiggle a paperclip or other similar metal probe (1.25 mm is the official diameter I think) into the little hole at the edge of the key face (this retracts the "detent" and allows the black cylindrical sleeve to unscrew).

3. With the paperclip still in place you can now unscrew the black cylindrical sleeve that surrounds the locking cylinder and remove both items.

Clean and reassemble in exactly the reverse order.

My mistaken idea above failed to take into account the fact that the "detent" is only released in position 1. I suppose an alternative would be to drill out the entire cylinder. You would only have to replace a cylinder then. But if you clean your cylinder out when it starts to get sticky then it shouldn't ever jam up in the first place. Even with a cheap brass key.

By the way, I think it is even easier to do this for earlier model 123s.

Miner beat me to it. I did a DIY for the door locks if you want to do them too.

Thanks Miner. Could a high-pressure blast of air right into the lock help to blow out any filings in there? Is there a potential for disaster?

I wouldn't say there is a potential for disaster, but I also don't know how well that would help either, as the cylinder butts up against the steering lock mechanism, and so it doesn't allow for a lot of room for air to circulate. If my lock were stuck, though, I would pretty much try anything to get it to budge.

But if all you are wanting to do is blow the debris out of a functiong lock, then I would say you are way better off just removing the thing as per above. There is no potential for disaster that way.

I used your DIY to do my door locks just the other day. Thanks for putting that up. It helped me a lot. I posted a little addendum to your article here:

http://www.peachparts.com/shopforum/showthread.php?t=157511

suppose one could just cut most of the end of the key off and jam it in the ignition using whats left of the stub to turn it thereby avoiding friction :D

Glad to see it helped somebody out.

I think I paid about $15/ea for the MB ones at my local dealer...

Hi,

I am having a little problem with the keys in my '83 240D too.

The round headed one works in the ignition and the doors and the square headed one only workes in the passanger door and ignition. Neither will even insert all the way in the glove box or trunk lock.

Is the Valet key cut different or have a different blank cross section? Or what else might be the problem?

Thanks

Ron
'83 240D

That just meant the car had an alarm. Nothing more. You can go to a craft store and get some red dots for the key and stick them on!
:D

The square headed one should be the master key and should work everywhere. The round one should work for everything except the trunk and glove box (at least that is what I read -- I dont have one and have never used valet parking anyway). It does seem strange that the master key is not working in the glove box or trunk or in the driver's door. But your saying that they don't even insert all the way might be a clue. When I cleaned my driver's door lock it was all packed with grime and especially the little cutout that the tip of the key slides into. It kept the key from going in all the way. This was very awkward to clean but you can do it if you work at it. This might be the trouble with the trunk and glove box.

My lock looked like it was packed with graphite and the locksmith I went to the other day told me to avoid it.

I think I would start first by removing your driver's door lock and seeing if it is gunked up. At the very least you can see why your valet key works but not the master. Follow bgkast's DIY and my little addendum too. Then you can move on to the trunk and glove box. I dont know how to service those but I bet some others here do. Or you could just figure it all out as you go (this is my prefered way of doing things :D).

My brother is a locksmith, he says Locksmiths always like it when people squirt Graphite in their locks and some time later bring the car in to get the locks fixed, all they do is squirt WD40 (or similar) to flush it out and charge them a service call, what $30?

The master key is probably worn, look at the cuts on it, if they are getting rounded then its worn, a new key is what you need (code cut from the dealer, hint ;) hint)

The square key is the one that is almost new. It was dealership cut. The round key is very warn and possably origional.

What is the differance between the master and the valet keys in cut or otherwise? To me they only look different in the head, not the grooves or cut.

Thanks,

Ron

The keys wear down over time. I have the original master key for my car and it has to be turned one way to fit into the new ignition switch I installed a few months ago. When it goes in the wrong way it doesn't fit!

Aha! yes that is the sign of one side worn more than the other, I suffered with a key like that unitl I realize done day it might not work on the "good" side then I would be in real trouble!