Please Help, now trunk wont open? 87 300E - PeachParts Mercedes-Benz Forum

#1 05-08-2002, 05:06 PM

I went to the gym to work out, had all my stuff in my trunk, close it, lock it, come back and it wont open with master key? WHAT THE HELL IS WRONG! I'm ready to bust it open!

JimSmith · #2 05-09-2002, 12:22 AM

Mateo,

The trunk lock performs a few functions and the workings can get a little complicated. If you have locked the doors and trunk using the central locking feature, does putting the key into the trunk key hole and turning it counter clockwise open the door locks? If so, with the key turned, push the button in and lift up on the trunk lid, and it should come open. If that does not work, remove the key in the vertical position, and cycle the driver door lock, then see if the trunk opens (when the doors are also unlocked).

If that does not work, I think you may have something out of adjustment. Kind of a "Catch 22" situation though, since you have to get the trunk open to make any changes to the way things are working. Good luck, Jim

Benzomatic126 · #3 05-09-2002, 08:50 AM

I have the same problem with my 1983 380 SEL. As Jim has stated it has to do with locking the doors. If I lock my doors the trunk is also locked and I cannot get in with the master key. If I unlock the doors, the trunk is also unlocked. There may be a certain way to unlock the trunk with the doors locked, but I have not found it. At least the frustration is gone after understanding why it will not open.

#4 05-09-2002, 11:50 AM

yea I've tryed to lock the doors, unlock the doors, nothing works. I realize that if you turned the to the left, it locks the doors and does not allow the Valet key to open the trunk. But I dont know what happened? It just wont unlock! Wont turn either direction. I'm taking it to a lock smith today. Thats the only thing I can think to do. Thanks for the imput.

JimSmith · #5 05-09-2002, 01:23 PM

Mateo,

You didn't say the key wouldn't turn before. Also, is the key slot vertical or horizontal?

There are a couple of issues to check, like does the key go all the way in? If someone put something in there while you were busy doing something else, or, some crud just got in there over time and has lodged so as to prevent the mechanism from moving enough to unlock, you will likely have to go to a locksmith. If the crud can be washed away with WD-40 or the like, you might try squirting some in there. You might also try a newer key with the features that engage the pins in the lock a little less worn.

If the key slot is vertical the vacuum system for locking should handle unlocking. If the slot is horizontal, it won't. If the slot is horizontal the problem is likely in the trunk lock alone, if the slot is vertical the problem may involve the vacuum actuator as well (assuming the central locking system functions normally except for this location).

Sorry I can't be of more help, but that is about all I can think of, Jim

#6 05-09-2002, 06:27 PM

Thanks for all your imput. I'm still at a loss. I've had it to two locksmiths and no luck. The position is horizonal. The key is in good shape and is not worn that bad. Looks like I'm going to have to drill our the lock unless I can come up with something else. They think a tumbler is loged somewhere and wont let the key turn. Any other ideas would be appreciated, but it looks like tomorrow I'm drilling it out.

JimSmith · #7 05-09-2002, 06:51 PM

Mateo,

I just went outside and tried my 88 300E trunk lock. This is the way it works:

With the slot vertical the trunk is synchronized with the central locking system

With the slot horizontal, the key only comes out if you turn it all the way clockwise (to the right), and the trunk lock is no longer synchronized with the central locking system. Turning the key to this position also locks the doors and gas filler cap.

Turning the key counter clockwise unlocks the car doors, gas filler cap and the trunk.

Turning the key is pretty hard and sluggish. I was a little alarmed and will lube the lock next. But the resistance is to the mechanism involved in the central locking system on my car, not the lock tumblers. I can feel the difference. There is a persistent resistance to turning the key all the way through the stroke, except at the very end of the full clockwise motion to lock things. Once the locks all clunk, the key turns, even if the range of motion left is very small, much easier.

If I was you I would get some good spray lubricant like WD-40 and flood the thing, a couple times, and then force it with the key. If you break the key off, well, that's another $20, but I think the key is pretty stout and should be able to force the lock to turn. Hope this helps, Jim

#8 05-10-2002, 10:31 AM

The lock smith I took it to tryed exactically that. They sparyed some lock lub in there, then some WD-40. But I dont think he tryed to force the lock to turn. That would make some sense. It has always given me a little bit of trouble like you described. I will try it. Anything is better than drilling out the lock and ordering a new one from Mercede$ Ben$.

#9 05-13-2002, 01:00 PM

Thaks Jim Smith, brute strenght was the "key" to opening the trunk. I will never use the trunk to lock the system again! Thanks for the tip.

JimSmith · #10 05-13-2002, 09:56 PM

Mateo,

Glad the gadget finally decided to cooperate! I was a little surprised at how stiff my 300E trunk lock was when I checked it. The other cars were much less difficult to turn. Glad to be of help, even if it was just encouragement to take a chance breaking the key before drilling the lock out! Jim