How do you remove main instrument housing on 1989 Mercedes W126 300 SE to replace Tacho speedo access gauge faces?
I presume this is like the one on the W126 280 S
A special tool is available with the agents but this is not essential.
Take a table knife with a rounded end and press it carefully between the cowling and the meter cluster, now carefully work completely around the cluster to loosen the adhesion between the cowling. The cluster is merely pressed in and there are no screws or tabs to break. It is only a friction fit.
Now using the blunt ended knife carefully lever the cluster out from the cowling working around the cowling levering the cluster a little at a time. Now use the two small buttons ( one to set the clock the other the odometer -or milometer )on either side to pull out the cluster. This should do it. If it does not:
Force a fairly long ( 2 feet ) length of ribbon using the blunt knife around the end of the cluster. You force the middle of the ribbon keeping the two ends in your hand. Now pulling the ends alternately work it a few inches towards the middle, then pull on both ends and the cluster should come out.
When putting it back wrap two pieces of BLACK ribbon, one around the electrical plug at one end and the other around the small metal pipe to which the vacuum tube is fixed, leving about two inches out of the cowling, this will be un-noticeable and enable you to pull out the cluster easily next time .Also rub some slicone POLISH ( the one for shoes will be fine ) outside the cluster and the inside of the cowling on the surfaces that meet.
I have done it on my W 126 280 S, so I know it works.
Mohan de Mel
SRI LANKA To add:
There's another way, undocumented, but it avoids damage to your dashboard cowling, the meter buttons, and for me, it's actually easier.
Using a short small Phillips screwdriver, unscrew the loudspeaker grille nearest the meter cluster, e.g. the left one if your W126 is left-hand drive. Remove the loudspeaker. In most cases I have seen, they are not themselves screwed in, but held down by the same screws as the grille. If the speaker wires are long enough, you can simply set it aside, otherwise just unplug the spade connectors, they're not difficult to reattach. A corner of the meter cluster should now be visible through the hole once occupied by the speaker. Push the meter cluster outwards (towards the seat). As the near side starts moving, catch the far side and pull out as far as you can. There are two connections to disconnect, as mentioned above. One is the vacuum hose and the other is the electrical connector. Once unplugged, you can lift the entire meter cluster out. Rafael