1981 300D non-turbo sedan with 200,000 miles. everything was working great until yesterday when i discovered that my key will not turn the lock on my drivers side door, which means that the vacuum will not engage to lock all of my doors. the vacuum system in general is working great, i don't think that's the issue as the key itself will not turn one way or the other. now my car is sitting in the lot at work with all doors unlocked! i can't push any of the lock buttons down because i think they're linked to the vacuum system (?). anyone have experience with this, any quick fixes? should i try to spray brake cleaner in the lock or will that mess things up? looked everywhere for help but found only vacuum related lock inquiries. thanks!

DONT SPRAY BRAKE CLEAN IN THERE!!!! Insted go to any walmart or auto zone and ask them about an Powered Graphite lubecration for lock make sure its not an oil b/c that would just screw up the locks even more, worst comes to worst you may need to get the lock for a reapair at your local lock smith, its cheaper if you remove the lock by yourself, also as for tempory you can unlock and lock all of your doors by using your trunk lock... i hope this helps

__________________
Current Garage
2008 Mercedes GL320 CDI 188k mi Repair/Work in progress
1994 S350 160k mi Garage Queen & prepping for repairs
2005 E320 CDI 203k mi Healthy & Daily Driver
1994 S350 357k mi Retried as parts car
1984 300TD 214k mi Blown OM617 Poss OM603 Swap??

Sold
1987 300SDL 200K+
1994 S320 181K mi
2008 E320 Bluetec 127k mi
1999 S420 130K mi
1980 240D 360k mi
15+ Others that has come, stay and gone

GONE, BUT NOT FORGOTTEN
1995 E320 SE 220k mi
1984 300SD 350k mi

I've had lock problems in the past I took the lock out and took it to a locksmith and they found a bunch of pocket lint inside the barrell. I would try pulling the lock out and cleaning it out. You probably have lint in there not allowing the key to go in all the way.

__________________

Great everyone, thanks for the ideas!!! Does anyone know where I could get a pictorial or a step-by-step on removing the door handle/lock? Is this a remove the door panel situation or can you pop this thing off from the outside? I've got the engine mechanics down, but this is my first step into some body work!

Thanks again!

I had exactly this issue on my 240D recently. Since yours got stuck all of a sudden the #1 thing to try is a different key. Its quite likely a key worn a bit might not work. I saw this on my car.
If that doesn't work you take the door panel off, take out the 3 screws that hold the door handle, there are 2 on the jamb side of the door which may be covered by a little plastic plate and 1 inside the door. Don't lose the moisture barrier while you're doing this.
Since the key won't turn you need to loosen (but not remove) the lock too. Thats held by I think just 2 screws in the door but I forget, you'll have to look at it.

With the lock loose you can pull on the door handle assembly and twist gently to separate them and take the door handle out. Reattach the lock to the door.

With the door handle out you need to drive out the roll pin that holds the rod that connects to the lock. When you take that bit off it'll also free up the spring and allow you to push the lock cylinder out of the door handle, this all sounds more complicated than it really is, when its in front of you its pretty obvious. It must be, I've done it after all.
When you take the lock cylinder out make sure you've got your key in it, otherwise you may drop lock tumblers and its then a job to put them back in the right order....

So wrap your hand around the cylinder to hold the tumblers in and slowly remove the key, now slowly open your hand without letting the tumblers spring out. Some of them are possibly not moving. Use some brake cleaner or penetrating oil or what not and get 'em all free'd up. On mine some were so badly stuck I had to use a brass punch and hammer. Definately a BRASS punch, the tumblers are also brass.
Once they're all free'd up and moving lubricate with graphite or something (I'm using a little white lithium grease too) and reassemble. The worst part of reassembly is getting the rod back into the lock but even that isn't so bad.

This is a good project that you can definately do yourself. Put down some newspaper and you can do most of it on your kitchen table.

The lock has to be removed from the inside by first removing the inner panel.

I would first try gently prying open the cover over the key slot of your lock and blowing compressed air in to dislodge dirt that may be preventing the key from going in all the way -- as Andrew has suggested. Use a tiny screwdriver and maybe one of those compressed air cans that are sold for cleaning computers.

I don't believe the trunk lock will lock any other doors on your car. That requires wiring that the W123 cars didn't have.

Can you lock the car from the outside on the passenger side? I'm surprised that the door buttons don't work unless the driver's door lock is jammed so that the vacuum actuators are always powered?

Jeremy

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

You will need to remove the inner door panel.
Make sure the window is up. Essentially the door handle is secured by two phillips screws.
The first is easy. Open the door. If you still have a round plastic cover on the door jamb near the butt of the handle, remove it. Then remove the screw inside.
Now you will need to look through a hole in the door in the area of the door handle. Once your eyes adjust, you will see the forward screw holding the handle in place. Remove with a long phillips screw driver.

There are a couple of ways the handle can be removed now. On some cars you simply slide the handle forward and "unhook" the rear of the handle removing the handle butt first.

Others require the use of the key. And then slide. Your problem presents a challenge to see if you can turn the key enough to disengage the key shaft from the latch.

Good luck.

__________________


Selling used Mercedes parts on Ebay...always changing...
cdplayer51 take a look!
____________