PeachParts Mercedes-Benz Forum - View Single Post - My odometer finally stopped working! Also more questions

tinypanzer · #2 05-05-2009, 10:42 PM

I just dealt with this issue recently, and it's not too bad a job.

First, you will need to order the 12 tooth gear from odometergears.com, or at least that was the gear used in my '90 300SE. I think yours should be the same.

Then, you have to pull the instrument cluster out, which is really no big deal at all. You can do a search here and see how to make the tools and how to use them. Easy.

Then you just have to open up the cluster enough to get to the broken gear. It is the tiny gear that sits on the end of the motor shaft that drives the odo.

You will notice that the plastic gear that was on there has split, leaving the metal insert that was once part of the gear on the shaft. You do not have to remove this insert. The new gear is designed to go over it. Here's the tricky bit - pressing the new gear on there. It's a tight fit, and mine never went all the way on, but it went on far enough to hold well and work properly. At some point I just decided that I was more likely to break it if I applied more force to get it to seat 100%. It has worked fine. Forces are so tiny that it's plenty "on there" to hold.

Once you get it seated, I would apply a dab of vaseline or similar heavy grease. The new gear has the tendency to be a bit noisy under certain conditions, particularly when it's very cold. Odometergears.com says this is normal, I say they could have done a better job of making that not happen.

Then the light bulbs - some have little plastic bases that twist-lock into cutouts on the circuit board of the cluster. Others are hard wired to the harness inside the dash. The twisties are easy to replace, the other ones require a splice and solder or a crimp.

Here's the cool thing - you can get all the bulbs you need from a junkyard cluster because only a few of the bulbs ever come on long enough to wear out and get dim. Those are the frontlighting bulbs, the low gas bulb, the brights bulb, and maybe one or two others. The rest of them only come on for a few seconds when you start your car and never accumulate any wear.

You can tell if the bulb is dim or not by if it has a silvery coating inside the glass. That coating is actually metal that has evaporated off of the filament and deposited itself on the glass. Very easy to spot.

If you can't find any, I have several good used cluster bulbs of both the twist-in and hard wired type.

Holler at me if you have any questions about it......