Mercedes-Benz Factory Service Bulletins: Trunk Troubles; Mysterious Knock

by | Dec 2003 | 0 comments

These suggestions and solutions for technical problems come from service bulletins and other technical sources at Mercedes-Benz. They are selected and rewritten for independent repair shops. Your genuine Mercedes-Benz Parts source can obtain almost any item designated by a part number. This issue of Factory Service Bulletins represents our first dip of the StarTuned toe into body-related information. If your shop does body work and mechanical work closely related to body repairs, please let us know what sorts of topics you’d like us to cover in future issues.

Trunk Troubles 1


Most Mercedes-Benz trunk latches form wedges in several dimensions to center the trunk panel exactly in its opening. Sometimes that fit can be too tight, regardless of the adjustment.

All Models

The trunk latch mechanism on Mercedes-Benz cars centers the trunk panel in the trunk opening, as long as the latch is properly adjusted with the bolts on either side of the latch. Even if you have that perfectly adjusted, however, that can sometimes mean the trunk fits so tightly it does not pop open when you press the release. The mating parts are plastic, and we’re inclined to suppose any such parts can work together invisibly, with no friction whatever. Nope. Sometimes even slick plastic surfaces are too sticky to let parts work freely. The cure? A dollop of grease at the mating surfaces. Don’t worry, the lock will still work perfectly well. It doesn’t depend on friction at the plastic surfaces.

Trunk Troubles 2


Spring tension determines the ‘antigravity’ lift of the trunk panel, and the position of the spring ends determines that tension. You’re not locked into one hole rather than the other: Increase or reduce the tension as needed by shifting the hole.

Models 124 and 201

If the trunk doesn’t stick, it could still wallow, or possibly it could bang open with a snap. The rate at which the trunk opens once released is determined by the spring tension, and that is determined (in part) by the anchor hole in which it is hooked. There is more than one anchor hole, and each one of them is every bit as official a Mercedes-Benz spring anchor hole as the others. If the tension is enough to raise the trunk panel to its full position, it’s correct. If the tension doesn’t open the trunk, doesn’t open it up all the way, or opens it up too fast, shift the springs in their holes. They don’t have to both be in the matching hole, so you really have three possible settings.

Mysterious Knock at the Door


A strange clunk in a door, gradually growing louder over a long time. But don’t take the door apart first, searching for something that’s not there.

All Models

As long as we’ve covered the spookiness of ESP in our major article this issue, it only seems right to think about strange clunks in the door. Before you open the inside panel to see what is rolling around loose, check the bolts that hold the strap and bar limiting the opening span of the door. If these rattle loose, you could hear just such a sound from the fittings and bolts in the door. It might be a good idea to either replace the bolts with new ones or inoculate them with threadlocker.


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