My 86 300E odometer and trip odometer is not working. Anyone out there removed and repaired these?

Thanks in advance.

1986 300E

do a search.... a fix was described by a mb tech along the lines of inserting a dowel into the gear spindle to hold the digits in place and greasing/cleaning the unit

I had the same problem with my odometer a few weeks ago and rather than send it out for several hundred dollars I decided to take a look myself. Here is how I fixed it:

First off, here is how the odometer works. The speedo cable turns a worm gear on the left side of the unit (if you are looking at the face) which then turns another gear. This second gear is attached to a thin metal shaft that holds all of the numbers in place. There are 6 digits for the odometer, hence 6 black gears but there is a 7th gear that is gray that is found to the right of the final black gear.

Beyond the gray gear, there is one more gear that turns another gear which turns the trip meter gear. The trip meter gear works in exactly the same manner with a gray gear to the right of the other black gears.

I have had two different failures with my odometer.

1) The first problem I had was a very easy fix. What had happened was the first gear (connected to the worm gear on left) had slipped out of the worm gear. I slid it back into place and glued a cap on the metal shaft on the other side so it wouldn't slip out again.

2) This second problem was a little harder than the first. The metal shaft was no longer turning the final gray gear on the odometer (it was slipping) so the numbers weren't rolling. To fix this, I removed the face and VERY CAREFULLY epoxied the gray gear to the metal shaft. If you are not careful you may end up glueing everything together and it won't work correctly. Just a quick reassembly and it will work again.

If this task sounds too daunting for you but you don't want to pay lots of money email me and I'd be happy to do it for you.
Oh, and I'm not responsible for any odometer fraud...

Peter
1988 300e
1988 420sel

I fixed mine about a month ago. The infamous grey/silver gear on the far right had worked loose from the shaft (do a search, this is usually the cause). In my case, the shaft had slid to the left far enough that it fell out of the housing on the right-hand side, causing it to disengage from the gears below it that drive the trip odometer. If the gears aren't all held together, nothing turns.

The fix was simple. Like others on this board have done, I used a small drill bit to push the shaft out and hold the wheels in place. (I wasn't too careful since mine had been out of commission for so long that I had to advance it about 10K to catch up.) I used a pair of pliers to rough-up the spot where the silver gear goes. Then I put it back together and the silver gear fit tightly.

NOTE: The scratches you make in this spot can be barely visible and will still create enough friction to keep the gear in place. I wasn't sure it would work because I could barely tell that I had scratched the shaft. Now I've gone about 1000 miles and it's working like a champ.

Word to the wise - never reset the trip meter while moving -- EVER!

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Jay
1998 S320

Thanks for the help in such great detail guys! This forum is the greatest!

1986 300E

JSlabotsky
Your thread to the original post bit me! "Don't set the tripometer while moving." Wish I had known that earlier!!! My odometer and tripometer stopped working recently so I did a search. After reading how to R&R the cluster I did the odometer/tripometer search and started reading. When I hit your thread to the post I knew I had done something wrong. I think I'll be able to handle the repair yet I am wondering what I did when I repeatedly pressed reset while moving. Do you know? Thanks ~ Steve

Well, I'm just echoing what other people have said. I wish I had read this forum before I broke mine.

When you do the repair, you'll be able to tell why this happens. The top stack of digits is turned by the input gear from the speedometer. A gear on the far right of the stack turns a gear in-between the top and bottom stacks. The middle gear then turns a gear on the far right of the bottom stack. Follow all that?

The only thing keeping the top gear fastened to the shaft is friction. If something causes it to keep still while the shaft is being driven, it can break loose and just spin freely on the shaft. Usually doesn't happen until the car has a lot of miles on it (say 100K or so).

When you reset the trip meter, it binds up the gear that is driven by the top stack of digits. Since the input shaft is still trying to turn, but the gear that drives the trip meter cannot turn, something has to give and the shaft starts slipping inside the silver gear.

Probably not as good an explanation as seeing it for yourself. When you fix it, it will all make sense.

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Jay
1998 S320