Ignition switch problem?

[blhfla]

My 85 300D has begun to show signs of an ignition switch issue, I believe. Over the past few weeks, it has intermittently (on occasion only) not turn off (glad MB put in the emergency kill switch on the linkage) and not start (I had to turn it "off" and remove/reinsert the key to get it started- but only once so far). It also seems to hesitate sometimes before kicking the starter over.

Is this a soon to be dead ignition switch? If so, do I just replace the whole mechanism? Anyone know how much they are from MB or do I chance it at a junkyard?

[Mustang_man298]

Sounds like the shaft/tab between the tumbler lock and the switch is either broken and barely gripping on raw friction or stressed and about to twist off.
I've seen that type of failure many times on several cars, usually caused by old grease in the switch getting gummy and putting excess stress on it when you turn the key. I would fix it asap, and the wrecking yard might be a hard stretch, these things appear to be pretty well built. When I got my car the P.O. had lost the keys, I unbolted the column and dropped it to try to bypass the switch to get the steering unlocked so I could get it on the trailer, when all was said and done, I had made no progress, the ignition "looks" like it'll pop right out if you undo the banjo clamp, but it won't. I finally ended up putting a floor jack under the front member and using that to steer it onto the trailer, then ordered some key's by the vin #. (Was cheaper than a locksmith)
The good news is, if it is built like most locks I've seen, then even if the tab to the electric switch busted, you could still be able to remove the tumbler with the key as long as it turns, and then get in with some needlenose pliers or a pick and get the remains of it out.
-Chris

[blhfla]

Diesel Giant has a great writeup about removeing the lock/tumbler/switch. With my key working I can still remove the lock assembly from the steering column, but do I need a whole new assembly or just the "lock cylinder" which I guess is the same thing as the "ignition tumbler". Or is it? Is that all I need to replace? Or are the the contacts in the lock assembly the problem? I haven't taken it apart yet (because it is my only transportation right now and I want to gather ALL the parts I need first) so I only have Diesel Giant's pictures to go by, which makes it somewhat difficult to visualize how it all works together.

[JamesStein]

Take a look at this page I started a long time ago but never finished.

http://raptusregaliter.gig4free.com/W123/index.html

The important thing is to get the ignition out and figure out what the problem is before it fails completely.

Your problem sounds very similar to what I was having with my car.

Your mileage will varry with a donor from a yard. The main problem you'll run into is, its tough to get these things out without the key. If the yard has the key, odds are they will charge you an arm and a leg for the assembly (my local yard wants $120 for it. New is $169.00 from Phil here at Mercedes shop.

[blhfla]

Thanks JamesStein. I'm thinking my problem is a worn ignition switch, because my key/tumbler inserts/removes/turns 100% fine. So I think after 21 years and 205K miles the electrical contacts have worn enough that they don't make good contact on occasion (like a worn distributor cap on an old gasser. If I'm going to drop the dash/steering, I might as well replace the switch and vacuum line switch on the lock assembly (at about $30 for each they're cheap enough) - I only want to get under there once. Does anyone think these could NOT be the source of the problem?