I just posted about a problem with my car door lock. Shortly after posting I found a solution, and wanted to share that with everyone on a positive post (as opposed to one that says I have a problem, that not everyone will read if they don't yet have, or didn't have that problem previously to post a suggestion.

Easy, quick, and SSSSsuper effective! Spray some lithium in your door locks, and they will work like new, if not better.

Incredible difference!

1991 300d, 200,300

If you mean into the tumbler, that's a bad idea.

Lithium grease will attract dust and dirt and before you know it the lock will be gunked up.

Only use dry lubricants in lock tumblers. WD-40 is bad, Lithium grease is bad, motor oil is bad. Graphite is good, silicone is good.

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'84 190D 2.2 5MT (Red/Palomino) Current car. Love it!
'85 190D 2.2 Auto *Cali* (Blue/Blue) *sold*
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I 2nd the opinion about lithium grease being a poor choice for lock tumblers. Especially those that are outdoors a good portion of the time. Lithium grease really is a dust magnet, and will be gummed up quicker than you think from environmental factors. It'd be different if it was an interior door lock on the 10th floor of an office building. Silicone or similar sprays that leave little to no residue are a much better option for continued operation of the lock tumbler in the long run.

I have used WD40 in the past with some measure of success, and did not experience any troubles with it, but it is good to know that is another item to put on the list of "things not to use in a lock tumbler", LOL. That's what I LOVE about this forum; we get to learn from other peoples past experiences.

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2007 Dodge Ram 3500 Cummins Turbo Diesel 4x4
1994 GMC S-15 pickup 4.3 5MT
1985 300 SD
1978 300 CD
1962 220-S Fintail - awaiting restoration

We used graphite lube in the front door lock of our house. It worked wonders.

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1982 300SD -- 211k, Texas car, tranny issues ____ 1979 240D 4-speed 234k -- turbo and tuned IP, third world taxi hot rod

2 Samuel 12:13: "David said to Nathan, “I have sinned against the Lord.” And Nathan said to David, “The Lord also has put away your sin; you shall not die."

Per Locksmith's advice...

And it works on locks that have been "Frozen" by disuse.

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'84 300SD sold
124.128

I don't know what MB recommends....but as usual with the cold onset, my door lock tumbler was sticking again(small doors are long gone) and I used silicone spray as well...freed it up, cleaned out the gunk and a few weeks later....still working like a charm!

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I discussed this with a lock smith a few years ago he claims graphite was a thing of the past then he showed me a special lock smith silicon spray at $20 a can. I never bought it but use the readily available silicon spray yearly on all locks no problems since.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

As I answered in the other thread that the OP posted on this, the gold plated answer is to completely disassemble the switch and reassemble dry. ANYTHING you put into the lock mechanism stays there, including graphite. In time, any lubricated car lock will accumulate a sticky mess. As a stopgap, you can first use a paint-safe carb or brake spray to clean out some goop, and then apply a light spray oil to lubricate. Once your lock becomes sticky, this will need to be repeated from time to time.

The problem is that once the lock get sticky, inserting the key is like running a fine saw blade over the pins. They gradually wear and when they reach the point that they mismatch, they will cause the cylinder to bind. The keys seem to be harder than the pins, so the pins wear more than the keys. If you use a new key in a sticky old cylinder, you will likely ruin the cylinder. This is because the new key will try to lift the sticky pins just a bit higher, thus increasing the chance that they bind.

As mentioned on the other thread, you can find instructions for opening an ignition cylinder and adjusting pin height on my website, and I will follow up soon with similar instructions for repairing door locks, as well as instructions for removing and cleaning the pins and springs.

Lock190

I use the lock cylinder grease spray from MB. PN 002 989 06 51
Pic of it attached

Attached Thumbnails

 

interesting.... I wonder what it consists of, chemically? Does the back of the container happen to say what it contains?

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2007 Dodge Ram 3500 Cummins Turbo Diesel 4x4
1994 GMC S-15 pickup 4.3 5MT
1985 300 SD
1978 300 CD
1962 220-S Fintail - awaiting restoration

There is no information on the container that shows ingredients.
See the 2 attached pics.:
One shows the back of the container, the other shows the useful tip...depress and dispense.

Attached Thumbnails

   

Thank You,

Mxfrank !

Do you think Your described Procedure is a good Idea in "Advance Maintenance"
BEFORE you need to buy a NEW Lock Cylinder ?
for older locks that haven't seen either Texas or Stuttgart in 100K?

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'84 300SD sold
124.128

If you let the lock get to the point where you just can't remove the cylinder, then it's a big deal to drill out the cylinder and replace the entire assembly. I find the cylinders begin to stick at about 150K miles. I'm pretty comfortable taking them apart now, so it's no big deal to PM them before the problems become impossible to fix. BTW, here's the companion article on door locks:

Repairing Mercedes Door Locks

Go to the dealer and request the SDS (safety data sheet, used to be called MSDS). By law they have to give it to you.

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Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech