124 Door Lock re-key? - PeachParts Mercedes-Benz Forum

Maxbumpo · #1 01-18-2019, 01:09 PM

Anyone BTDT? The driver's side door lock on my 124 wagon is going south, I can lock but can't unlock because the tumbler won't turn far enough to unlock.

I've got a complete set of door locks from a same year sedan (1987 for both cars, donor and recipient) and I've got keys for the donor.

Ideally I can take parts from the donor and restore function to my daily driver wagon and keep it one key for all locks and ignition.

sixto · #2 01-18-2019, 01:54 PM

Have you tried a dry graphite lube? Can you take key and tumbler to an old school locksmith for repair? It probably doesn’t have to be brought to new standard. Maybe the tumbler just has to be loosened so it works with that key at the risk of working with similar keys.

Sixto
98 E320s sedan and wagon
02 C320 wagon

Stretch · #3 01-18-2019, 02:45 PM

In my experience you are better off removing the lock that is giving you trouble and spraying loads of cleaning fluid (such as brake cleaner) through it and then doing the same with a pressurised lubricant (not WD 40). I've found there to be loads of swarf in the lock that causes the trouble. Once removed - with luck - the lock will work for a little longer.

If you still have the original keys the dealership is (well was) able to get a replacement lock if you want.

Changing a whole lock set is a bit of pain - but when needs must...

sixto · #4 01-18-2019, 04:37 PM

It’s worth checking but I read MBUSA is out of the business of cutting locks and keys to VIN for 124 and older models. They sell lock and key sets but not cut to VIN.

Sixto
98 E320s sedan and wagon
02 C320 wagon

Maxbumpo · #5 01-18-2019, 07:04 PM

Thanks guys, I'll try the clean and re-assembly.

I didn't explain my idea very well. I'd like to use parts from my car and the donor set to create a new driver's door tumbler / lock assembly that will open with my original key, which also works in the ignition and the passenger door lock.

Has anyone taken a 124 door lock tumbler out and rearranged / replaced the wafers inside so that it works with a different key? I know that folks have done this on 123 cars.

jbach36 · #6 01-18-2019, 07:50 PM

I used white lithium spray on my locks and it made them like new. There are warnings on the internet not to use oil because it attracts dirt while lithium does not.

Maxbumpo · #7 01-19-2019, 08:57 AM

FSM Procedure 72-240: Well the lock / tumbler assembly is very easy to get out of the door: on the back edge of the door, remove cover over little hole, insert 3mm hex and turn out (CCW) hex screw four turns. Insert key, turn to unlock (CW) direction, push lock / tumbler toward rear of car and pull out. Easy peasy, takes me longer to get the tools out than to pop that lock / tumbler out.

Washed it out well with brake cleaner, then with Houdini Lock Lube, no change. Lots of black juice ran out, I kept going until it was fairly clear, but nope.

It looks like there is a pin at the end of the assembly that can be removed, which then allows a piece and a spring and then a cir-clip to come off, and then just maybe the tumbler will come out of its housing. There are two more pins inserted into blind holes, I guess I'd have to grind the housing off on the blind side to be able to drive those out, but I'm not sure what that would gain me unless my first guess about removing the tumbler is wrong.

There is one white wire, must be for the alarm system or door lock system, which is attached to the lock / tumbler, and I don't see how to easily remove it. Given it can only send one signal (ground or not ground) I'm thinking it must be for the alarm, as the central locking system would require two signals, lock or unlock.

dlssmith · #8 01-19-2019, 10:29 AM

I ended up using a paper clip with about a 1mm bend at the end to hook some of the debris that had collected inside the lock. Gently, of course. And with the brake cleaner and lock lube. I got the lock working pretty well. Just washing it out didn't do it. Had to hook the crap left inside. I did this with the lock removed so as to be able to use gravity to assist and I was able to use compressed air to clean it too.

Maxbumpo · #9 01-19-2019, 12:24 PM

Well I was wrong on the wire, it actually has three conducters inside for the locks and the alarm. There's a big plug on the end of the door, remove that and the connection plug for the wire can be disconnected, so now the whole lock / tumbler assembly comes out.

This site discusses 201 door lock repair:
https://www.coolcatcorp.com/Mercedes%20Locks/Door%20Lock/190%20Door%20Locks.html

His procedure is very close for a 124. My lock required only the tang pin to be removed, the other two pins are in blind holes. Once that pin was out, tang assembly comes off, and then the tumbler can come out with the key inserted and turned 90 degrees to either the right or the left.

Careful! Don't pull out the tumbler too fast, easy does it, now you have access to all the wafers and springs, and there is a little ball bearing that lives in there too, so don't loose that.

Maxbumpo · #10 01-19-2019, 02:49 PM

Once the tumbler / key were out, I made a little diagram of the orientation and slowly pulled the key out, hold the wafers to keep them from flying off. Key out, wafer ends pointed horizontally, I worked from one end of the tumble to the other, pulling out wafer, marking my map with what number wafer, laying the wafers in order, and finally using a very fine pointed tweezers I pulled out all the springs.

Four of the positions have wafers that are two part (two springs) with different numbers on each sub-wafer. Not sure what that is all about, but they are a pain to keep straight and then get lined up when putting the key back in.

Be sure to keep track of the little ball bearing that is in there. It fell out before I saw where it lives, so I put it back into a small hole on the inside. That seems to be the right place for it.

Cleaned the tumbler and the cylinder really well with brake cleaner, sprayed off with compressed air. Cleaned each wafer with a rag and alcohol individually, managed to break the end off one of the springs, but re-used it anyway, didn't seem to harm the operation (yet).

Put on a very light waxy lubricant (Boeshield T9) and put it all back together, no joy. Same problem, key will turn in lock direction but not in unlock. A few of the wafers stood proud of the tumbler, so I carefully removed them and filed them done. I worked from tallest down and re-try the lock after each was corrected, until it finally works. It is still a little notchy and you have to hold your mouth just right, but it works. Put it all back together, now on to house chores....