So, I got this 300SDL back in December and I finally got one project done. Before I can do things like fluid changes and maintenance items, I feel like I needed the ODO fixed so I can keep track of stuff. Also, because I have not done the fluids, I didn't want to drive it too much considering I don't know when things were last done.

Anyway, besides the odometer not working, the cluster also had these issues:

Faded needles
Faded gauges
non-functioning temp display
Weird plastic degradation (see pics)

Okay, so for this "weird plastic degradation"...I saw this once before on someone else's pic on this forum but I don't remember who. It's like the plastic is "growing" (for lack of a better term), these light colored bumps all over. They can't really be cleaned off. You can sort of scrape them, but, considering they were all over the cluster and inside the plexiglass, it was going to be near impossible.

Pics of deterioration:



Another one:



I had this old 420 SEL cluster sitting around and the housing was in excellent shape. I just needed to swap everything over.

Here is my before shot. Sorry it is crappy, but, I had to scrape it from a youtube video because I forgot to take high quality before shots (note yellow needles and broken temp display):



Basically, here is what I did for the refresh:

Swap all the gauges to the 420 housing
Paint the needles
Apply new gauge face overlays from whitegauges.net
Swap over the idiot light gels
Replace odometer gears with new from odometergears.com
Replace only the illumination lights for nighttime (#2821's)

Both the drive gear and the secondary gear were toast. For $65, odometergears.com will send you three of the gears. I guess the others just aren't prone to failure. Here's a pic:



Removing the idiot light gels...this was critical to me...yeah, technically, I could just use the 02 sensor light as my glow plug light, but, I like to keep things the way they are supposed to be.

First, peel down the felt strip a little:



I used an x-acto knife to get things started:



Did the same on the SDL cluster and swapped it over.

To renew the gauge faces I got a custom set made by the proprietors of whitegauges.net. Oddly enough, "custom" means stock colors. The white ones they offer are only $20 a set. It costs an extra $30 dollars (total $50). These gauges are just vinyl overlays. I would give the quality a 9/10. Only you would notice any imperfections. They were easy to install. Their website has videos, plus, they send you an instruction sheet for a w123 or w126 specifically (with pictures) which is nice. I also bought their orange needle paint. It's a little "oranger" than stock but its pretty close.

And here's the final product:



Took it for a spin today and the odo works great as well as all the gauges and lights (far as I could tell).

Now I can start all those other maintenance items!

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1986 420SEL W/1990 560 SEL Full Power Interior Swap
1995 E300D
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