W124 Lock Cylinder Replacement: How-to
 

My ignition suddenly got difficult to turn...so, I quickly called up a local dealer and ordered a new lock cylinder. Better to catch it before it turns into a major problem! Since I didn't see anything for the W124 chassis, I thought it would be appropriate to write up something quick for it :cool:

If you have the service manual cd, the literature is under the Chassis and Body section, under steering (Removing and installing lock cylinder 46-8110)

• Tools / parts needed

1. New lock cylinder (as of 9/11/09 - $91.50 from dealer)
2. Screwdriver (for removing trim)
3. Hanger or wire (roughly 2 mm diameter wire)
4. Diagonal cutters
5. Ruler / tape measure

• Test hanger thickness (or welding wire, etc).
• Construct tool: Unbent length = 32cm. Two 90 degree bends with two outside 15 cm lengths leaving 2 cm in center. Use diagonal cutters to cut 45 degree portions off the tips (on the interior side - see picture). I also used a little bit of sandpaper to clean up the cuts.
• Remove trim.
• Insert wire tool with key in number 1 position (mine was a bit of a pain to get it to release the lock cylinder).
• Pull old cylinder right out.
• Remove key from old cylinder and swap cylinders in cap (black with small detents).

• Turn key to number 1 position, align cap markings with key.
• Insert new cylinder.
• Turn cap until it sits flush with lock cylinder in appropriate orientation.
• Test key / start car. If it doesn't turn easily, it's probably not seated correctly or the cap isn't flush like it should be.

:)

W123 ignition lock replaced
 

Coincidence - I just did mine. Crosslink to other thread: http://www.peachparts.com/shopforum/diesel-discussion/260558-ignition-lock-housing-replacement-re-key.html

Ordered new lock from dealer, price was same ~$90, had to show title and driver's license to get matching key for VIN. Parts guy agreed that they clamped down on selling VIN-matched keys/locks last Oct or so.

New lock came with matched key. Key tests good in trunk/doors. Not bad for an '83.

Technique was similar, only 123's have a single slot to release the tab. I used a jewelers screwdriver. 46-640 in the 123 FSM. And 1.25 mm means 1.25 or smaller, not 1.5 or "close enough".

Per the FSM, after tightening the cap all the way, I had to unscrew the cap back almost one full turn to engage the locking cylinder. It's snug and flush with the minus-one turn.

The PO was kind enough to re-install the highly secure lock in the pic below. Yes, you eagle eyes may notice that there are no tumblers in that cylinder. I'm bummed that I can't start my car with a screwdriver or pull the key out while it's running anymore.

When I did my 240D (upon convincing from the kind forum members who saved me paying the dealer), I got away with just using just a (beefy) paperclip to get the cylinder out. That security lock looks interesting... The W124 was a little more of a pain with aligning the cap, but still pretty similar to the W123.

When I went to the dealer, after making a copy of my registration and ID, they had to go outside and check the VIN and test the key in the door (I ordered a valet key for the sum of $28). I'm kinda glad he didn't try to open the door after unlocking it with the new valet key...as it would most likely have set off the alarm :)

I really think it's a lot simpler to get these right away when you're having key trouble...15 minute job versus probably at least a couple hours (and some hair).

I have to hold my mouth just right to lock my driver door and my ignition is getting a little hard to turn at times.

Could this just be key wear or should I replace them both?

Well, you could try the passenger door...I'm sure it gets used less than the drivers for unlocking. That'll give you an idea if it's the key that needs replacing. :)

With that said, if a new key is difficult to turn in the ignition (i.e. you have to jiggle it to get it to work), you're going to have an extra master key because one comes with the ignition cylinder. When I bought a valet key, it was around $28, so, I'd expect something around that for a master key.

OK, I should have done that while it was still working...
 

...any suggestions on how to get the cylinder out with as little collateral damage as possible if the key doesn't turn anymore at all? :mad: (It's the '87)

Sander
 

Clamp the offending key in a sander(You're looking for the "Vibratory" Power)
and see if it'll "Free Up" enough to turn the key to position #1 !

Wow! Crazy Nate's description and photos for the ignition lock switch saved my butt. Note that the diamater of the wire is critical. Too loose in the slots and it will not release the cylinder. Too big and you can't get it in. Likewise, the 45 degree cutoff is critical as the end of wire must slide over the flange that locks the cyliner into place to release it. It also must slide over the housing retainers to release them.

Here is an additional lesson learned the hard way. When the lock cylinder and the housing come out, they come apart. I was curious about how the housing fit into place. To make sure I got it lined up correctly, I reinserted it, without the lock cylinder, and, guess what? It locked back into place, but without the lock! S---! It took me 30 minutes of studying the arrangement to get it back out.

Thanks Nate.

Tom Bohs

yesterday the lock in my '87 300TD just stopped turning. there was absolutely no warning, it has never given the slightest hint of going bad. i tried both original keys, the vibrating sander, spray lubricant, compressed air, everything i read on here. no joy and the lock would not turn so i could not get the tumbler out. this is my wife's daily and a much needed vehicle to our family so i had to drop all other work and get it drive-able.

i had to get out the power tools and destroy the tumbler and hardened cover to extract the lock cylinder. i have another 124 wagon that is idle at the moment so i replaced the ignition lock with that one until i can get a matched tumbler from the dealer.

our car has just under 300,000 kms and i would suggest anyone who has this kind of mileage to re/re the ignition cylinder as a preventive measure. i wish i had done this. extracting the tumbler by destroying it isn't so hard, but hacking the car made me curse. such a brutal method of 'repair'. my 4-year-old wanted to know why i was breaking the car. then she said something very smart: "do you have to break it to fix it?". from the mouths of babes indeed.

Make sure you push it all the way in as far as it will go. I spent about half an hour with the wire tool almost all the way in, squeezing the wire together to try and get the barrel to release. This wasn't working, but as soon as I pushed the tool in a little bit more it released straight away.

Great pictures. This posted helped me. I had a crude wire I had just cut and it was not working. I cut another one and angled both ends with the bench grinder and I was easily able to release the cylinder which definitely had serious damage. That takes care of my E320. My 300D is next.

What should come off and how
 

I know this is an old thread but I am having difficulty removing the black cover that the ign cylinder sits in.

I have the right size wire [ a dental tool] stuck in the hole with the key at #1. but I can't get anything to move.
I tried turning on the black cover with my hand and then, carefully with a channellock but it does not budge.
Should it just unscrew or does the key/wire have to turn ?
I don't want to damage, break or force anything.
Any advice and clarity?

I read Nate's description then headed out to do the job. It was later that I read this narrative and couldn't believe how precisely it depicts my experience. I wish I would have seen it BEFORE I started!.

I want to reiterate the importance of the angle cut of the tips of the wire and be sure the angle of the cut is as shown in the diagram. The sharper the tip the more likely you are to catch the release hooks on your first try. Be sure the length of your wire is sufficiently long because the release hooks are past the end of the the lock cylinder. And be sure to install the lock cylinder and the bell housing as a unit, rotating each separately until they fall into place.

Tom Theimer

HOORAY for this thread....I had to use bailing wire as my coat hanger was too thick but it popped right out..in fact, I had a harder time getting it back in.

Actually, after I removed the trim piece I pulled on the housing and the cylinder had seemed to separate from it and the whole unit was going to come out. I was hesitant to just pull it out at that point so I rotated it back into place until it locked and then used the tool to remove it as per the instructions.

This was performed on a 87 300TD Turbo