Home Depot and Lowes cannot make a key for my 240D- their automated machine doesn't recognize it.

Do I have to go to a MB dealer? Or a locksmith?

I have exactly one key for my car and that makes me nervous.

Thanks-
Lynn Kasdorf

You can get a replacement master key (or valet key) keyed to your VIN, from the dealer with the title, current registration and photo ID.

They come from Germany, about a week on average and cost around $25, last time I ordered two spares a few years ago for my 1978 W116 300SD.
Some dealers require the car to be present in the lot at the time of ordering the key.(Home office policy for MBUSA evidently).

The plastic portion of the replacement key is poorly designed and it tends to break off after a few hundred twists in the locks.

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

When I owned a 123, I was able to get keys made at a locksmith. Later cars required keys made by the dealer.

A locksmith should be able to copy your key; however, if your key is old, worn or not an original MBZ key it would be better to get an original one from the dealer cut by VIN as suggested. Copying a worn or non-original key results in a marginal product at best. The keys from MBZ cut by VIN work very well and would be fine to copy.

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

I got one about a month ago from the dealer, they wanted registration, but to be on the safe side I also took in the title. It took a few days and cost $35 and worked perfectly first and every time. OEM is the way to go.

My local hardware store (not a big box like Lowes or something, they couldn't do it) actually had a key blank that say FOR MERCEDES on it. Made me a copy for $4, works great in my 84 300td.
The dealer up here wanted to charge me $75 to have one key made.

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1984 300TD -- summer daily driver
Many others that aren't Mercedes...

I need to know what dealers yall go to. A few dealers I called wanted anywhere from $50 to $80 for a single key.

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Current: 1975 450SEL, 83 300D, 88 Yugo GVX, 90 300D OM603 swap, 91 F150 4.6 4v swap, 93 190E Sportline LE 3.0L M104 swap, 93 190E Sportline LE Megasquirt, 03 Sprinter, 06 E500 4Matic wagon.

Aftermarket keys will eventually cause problems in the tumbler. The metal used to make an aftermarket key is inferior to genuine MBZ keys and the filings that wear off from an aftermarket key will cause the tumbler to fail. New keys can also be ordered from the MB Classic Center.

I use my original key on a daily basis, just wanted a spare in the case I lose my keychain, etc.

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1984 300TD -- summer daily driver
Many others that aren't Mercedes...

Go to a real locksmith, older the better, if he has an available blank with care (hence the old guy!) he can make an exact duplicut of what is working for you now.

If he doesn't have a suitable blank you or he will have to find that first then he can work it.

Couple things to consider with these cars. As the lock is used over time both the key and the in this case the leaf wafers of the tumbler will wear over time. There have been times when a new key would not operate an old lock easily because although the key was perfect the other worn parts are not.

The MB tumbler is designed so that the leaf waters are centered in the tubular key way barrel when a good key is inserted, they do not protruded into the TWO locking channels in the outer body shell. When a new key/perfect key is used because the leaf waters are worn one or more of them may not center perfectly leaving a small protrusion still intruding into the locking channel of the tumbler's outer body shell. Then the tumbler rotation is impaired, it seems to not be able to turn cleanly, easily and smoothly. Much of the time you can just wiggle the key a bit while turning and there will be enough slop to allow it to eventually move just enough to let it turn. Some times you can live with it sometimes it's too much of an annoyance.

In that case the only recourse is to fully disassemble the lock's tumbler and with the key you want to use inserted into the naked tumbler barrel inspect the leaf wafers and identify which ones would need a bit of protruding material removed to allow the barrel to fully disengage all the leaf wafers from either locking channel.

That is really not easy for some people so in the alternative they replace the entire lock and key as a set.

Bottom line if your key works good now a good locksmith can produce a clone of it pretty straight forwardly, probably not too expensively and might even welcome the challenge.

You can pretty easily pull the lock and take that and the good key you have to the shop with you that way he can fit it perfectly.

Do W123s take the M79 blank?

I had two spare keys made at an actual locksmith here in town, so not a Lowe's or Home Depot. Think I payed 8 dollars for 2 keys. They had no problems copying them. I have heard some horror stories about using such keys on a daily basis though. Apparently the copied keys are generally of a softer type metal that will wear down in the ignition key and leave metal fillings behind that can gunk up the ignition and give problems.

I made the spare keys just in case I lose the original so that I can still get in and move the car, but I will get a copy from the Mercedes dealer right away if I ever lose the original.

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"The MB W123 is so bulletproof, you can drive them forever. Which is a good thing as it takes that long to get anywhere."
Betsie: 1984 W123 300D (hobby, 280k miles)
Myrla: 2001 Mazda Protege 2.0 ES 5spd (daily driver, 130k miles)
The Turd: 2007 Toyota Camry (wife's car, 118k miles)

Unless someone has photos of an open cylinder with evidence of key shavings, I'd dismiss this as unfounded rumor. Mercedes locks, especially on the earlier cars, are nothing special.

The original keys are steel, the ones you get from a locksmith are brass. So yeah, I'd call that softer. Before I knew that I was using one made at a locksmith, thinking the original would wear down too far one day so I wanted to save it. Turns out the replacement wore out pretty quick so I'm back to the original which still works flawlessly.

Keep a brass one as a spare, but a replacement really needs to be steel. Shame nobody makes aftermarket ones, they could be a popular individual. Wish I had easy access to machine tools, I might do it myself.

-Rog

Now I wish I had saved a 300D key. Steel seems unlikely. My original 190D key is chrome plated brass. But it's ground off where the teeth are cut. So I don't think it's there for anything more than corrosion control. Chrome is very hard. Are your keys magnetic?

The important thing here is that the wafers in the cylinder are made of brass or bronze. If the key is harder than the wafer, then the key will wear out the wafers. So if you want to extend the life of your lock, you don't want a hard key.