The inevitable lock cylinder failure......and the cure

[UTn_boy]

Today my lock cylinder failed in the ignition switch of my 1979 450sel.  It's a late model, so it has the KESO style key and lock cylinder.  Unfortunately, they're no longer available.  (Part of Mercedes's ploy to discourage people from having/wanting a W116)  I didn't want to find a used one and end up having two keys to the car.  So I decided to give Mercedes a swift kick in the ass by disassembling and repairing the cylinder myself. 

The hardest and most trick part about doing this is removing the pressed in roll pin out of the front retaining ring.  I ended up having to cut the metal out around the pin so I could grab a gold of the roll pin with a pair of wire cutters for extraction.  It's ok do do this because when the lock cylinder is back in the car, the bezel that goes on over the lock cylinder will hide the area that has been cut out.  It's not a significant but, only about 1mm or so. 

As can be seen, most of the brass tumblers are standing proud of the core with the key inserted.  The tumblers are supposed to be pulled down level so the core will turn inside of the cylinder when the key is inserted.  If you're having a hard time following me, think of the dead bolt on your front door.  In order for the door to open, the metal part of the lock must be pulled inside of the door so the door will open, right?  That is essentially what the idea is in a lock cylinder, but times 10. 

Why does this happen?  Well, the first reason is that the tumblers are made of brass, and the factory keys are steel.  The brass tumblers are much softer and are quicker to wear, especially when a metal harder than the tumblers (the factory key) is constantly drug across them when the key is inserted and removed.  As the years go by, the grease inside of the lock cylinder dissipates, and eventually it's metal on metal. 

The second, and most preventable reason, is due to having a large wad of keys on your key chain.  Excess weight will wreak havoc, and in a short time.  This is particularly expedited when the lubrication wears away. 

So what is the solution since the lock cylinders are no longer available?  It's simple.  Once the core has been removed from the lock cylinder, you simply insert the key (preferably a new key) into the core, and file the tumblers down level with the surface of the core.  Clean and lubricate everything, and you'll be good to go for another plus or minus 100,000 miles.  And for heavens sake, lose the wad of keys.  Buy yourself a key fob from Mercedes, part number 108-890-06-61, and let that be the one and only key that hangs out of the lock cylinder. 

If any of you need this job performed, I'll be happy to help you out.  I'm not necessarily looking to make any money.  I'm only wanting to help others out in the face of adversity.  I've done this job several times on different models ranging from a 600 to a W126.  I rather enjoy the job, but you'll have to get the lock cylinder out since I can't be there to do that part.  All you need is a paperclip to remove the cylinder.  If the key will no longer turn, it may be too late.  At this point, the whole ignition lock/switch assembly will have to be removed from the steering column.  If that can be done, then there is a good chance that it can still be repaired, but no promises.  If it cannot be repaired, then you simply buy a used one, and I'll still be able to make it all work while maintaining the use of your original key. 

The whole point of this is to maintain the "one key fits everything" convenience.  I cannot stand having two keys to my car. 

[76116]

Nice one, thanks for sharing this...

[floyd111]

With all things one has to know and cover, when owning a W116, I would really welcome a "service" where barrels can get "refurbished"
I would think you stumbled onto a very interesting concept!
Count me in! I'll send you all my barrels, to be redone, before they break down.
It may be time to calculate your fees.
Are door/trunk/glovebox barrels as "easily" redone?

Next up: refurbishing Hirschmans and window lifters. There's a whole market out there!

[Harv]

Does the tumbler come out like this?

[UTn_boy]

Thank you for the kind words.  As I finish the job I'll post more pictures.  I also think I'd like to make a video, too.  Fair warning though, it'll be a novice attempt at filming. haha.  We'll see. 

HARV: Yes, that this how the lock cylinder is removed.  The key must be turned into position "1" before the paperclip can be fully inserted. 

STAN:  Whenever you're ready.  And yes, the door/trunk/glove box lock cylinders are serviceable, too.....but only if there are good bones to work with.  Sometimes the cast Zinc will be too far gone. This is usually a problem for cars that spent a life in coastal areas or in areas with a lot of salt on the roads.   
            I didn't know that Hirschman antennas were something that anyone was wanting repaired.  I've been repairing my own Hirshman's for several years now......
            I'm assuming you're talking about the window lifter motors?  I think those turn up from time to time NOS on ebay.  Otherwise, I'd imagine that they're a no brainer being such a simple motor. 

[revilla]

Very nice Aaron. Thank you very much. I see 3 phases. Repair after failure, recondition before failure (per Stan) and preventive maintenance (non-invasive). On the latter, any advice you can offer to avoid (read prolong) doing the more complicated phases of repair/rebuild?
Thanks again for such great tech note.

[floyd111]

The Hirschmanns are known to be very solid, but there are surely broken ones out there that would merit a rebuild.
The masts are still readily available and affordable, from hirschmann.
For my project, I would want a rebuilt Hirschmann, rather than wait for a breakdown one of these years.
This stuff will only get rarer by the years.

As soon as I have all cylinders out of the cars, and collected, I will find you again and we'll work out a process.
Still, it would be good to have some idea in mind about the cost of things.

And..the window lifters and -motors issue are a no-brainer. There WILL be stiff demand for such a refurbishment service.
The ones popping up on ebay are only second-hands, for a long time now.

[UTn_boy]

Revilla: Thank you for saying the kind words. Yes, I can offer advice.  First of all, after the lock is repaired, I clean them and then lubricate them with anticorrosive grease.  For maintenance afterward, I suggest buying a tube of the anticorrosive grease from Mercedes, ($11.00 USD) and occasionally putting some grease on the key itself.  As it is inserted, the grease is introduced, and the actin of the tumblers going up and down will distribute the lubrication.  You'll want to insert and remove the key a few times afterward and wiping the key off each time.  This will remove excess grease,a nd will also prevent grease from getting on your hands/clothes. 

Second, BUY A KEY FOB, and DO NOT put other keys on the fob and/or key chain.  I don't really like key chains much past how nice they look, as they scratch the dash and steering column.  However, they definitely pose no threat the the lock cylinder.

Stan, the power transistors and the electrolytics are what usually go bad in the antenna motors.  Corrosion is a problem in the lower quadrant, which will usually seize the pilot gear for the mast cord.  Over the years, I have amassed enough antennas to last me a lifetime.  I have this weird habit of feeling the need to snag every one I find regardless of its condition.  I'm certainly glad I've done this so long ago, as they're harder to come by now, and when you do see one on something like ebay, they want $400-$500 for it.  It's a joke. They're only worth about $50.  Granted, I'd definitely pay more if I knew it were rebuilt, low mileage, or NOS. 

Regarding prices, I still don't yet know.  I hadn't really planned on charging anything except shipping and the grease, which I would include with the reconditioned cylinders.  Send me an email and lets see if we can brain storm. 

Well, carbon piles are a dime a dozen for the window motors, and they usually clean up pretty good.  Guess I'll have to stay on top of my game huh? 

[floyd111]

This week I got lucky to bump into 2 NOS Hirschmanns, still in the box, but I have also snagged up 2 used others, haha, just in case. Never paid more than 75usd though, ex shipping. But, they needed new masts. That's extra, as is shipping.
I thought to maybe open them up and have a look-see what goes on in there.
Need to have the aluminium casing re-anodized anyways.

[ptashek]

Next up: refurbishing [..] window lifters.

My restorer suggested a rather simplistic idea, but with a high chance to just work - bolt on a 3-4mm thick hardened steel plate to the back of the window regulator to keep it a) straight, b) from flexing under load. He said there should be enough clearance in the door to do this safely, with the only downside being you gain about 2kg+ of dead weight per door.

I haven't done this, and opted for new ones from the stealership instead, but I'll definitely test this on one of my spares. Simple usually works out best

[revilla]

Thanks Aaron. Will follow advice given, hoping that the cylinder lasts longer.

[UTn_boy]

Stan, the aluminum housings aren't anodized.  Cast aluminum doesn't take being anodized to well, anyway.  It flakes off.   They're just plain old cast aluminum housings with no exterior coatings on them or in them.  Only the hardware that attaches to the housing that allows it to be affixed to the chassis is yellow zinc plated. 

If you find one that is in nice shape, simply clean it up, etch it with something like MAG wheel cleaner, and then spray a flat or satin sheen clear coat over it to prevent discoloration from oxidation.  Also, when the car is finished, the antenna motor will be hidden from sight anyway. 

Funny thing about the window regulators......I've never had one fail.  I recently bought one that has a problem,  but I don't yet know the what or why.  What I've found over the years, all in W108/W109, W116, W126, and W114/W115, is that the metal part of the door that the regulator attaches to usually cracks/distorts.  The repair involves welding the crack, and then welding a stiffening plate to the back sides of the door frame where the regulator attaches to. 

[floyd111]

good tips here!

[UTn_boy]

I thought it important to mention this.  Before any repair work is done the the core and the tumblers, it's imperative that a new key has been acquired.  In the following picture, take not of the two original keys that came with the car.  The top one is more worn than the bottom one, but they're both badly worn.  Notice how the top edge of the top key has a parabolic shape about it.  It's supposed to be flat.  Also, the actual cuts on the side of the key are extremely worn. 

If I were to repair the lock assembly with a worn key, then any new keys bought or made subsequently wouldn't work in the lock.  I'd venture to say that the cause of most lock cylinder failures is the result of both worn keys and worn tumblers.  Consequently, I can't do any alterations to the tumblers until my new key has arrived. If anything, just buy a new key for good measure.  Pretty soon, they, too, will no longer be available.  :/

[Harv]

Believe it or not, my local Mom & Pop locksmith had these keys in stock. They are Italian made keys by the name of Silca. He had to use a special machine to cut it and it took some time. Once he tested them, I told him to make me 3 or 4 so I'll have them. Then he said they are $45 each. I said I'm good for now.

Here you can see the OEM key vs the new key.