'81 240 manual...OK speedo, but "slow" odos...
 

This for me is a "new" car, and very lightly used...however, while the speedo (old version) seems accurate, both the main and trip odometers are reading about 50% of the mileage they should.

Any suggestions as to fixin' approaches? Would prefer a gastank additive that would clean up the problem while I drive :).

Well where would you put the gastank additive though? ;)

I believe there is a plastic gear which controls their function and just needs a little help. I heard if you rough up the shaft just a little (imprint with vice grips maybe) with something it'll work fine again, I'm sure somebody else can go into more detail than this.

A wee-bit of LockTite where the gear and shaft meet... Wait a little while until it sets up.

Do a search on it for exact directions. You need to pull the instrucment panel, use a drill bit to push out the old shaft and hold the numbers in place, rough up the old shaft where the pot metal gear is pressed on and push it back together. Voila!

Morgan / others...thanks! (more)
 

The "MBZ" diy articles are very helpful in a great many areas...all would do well to click on Morgan's post and copy the link.

Odd that MB would share such a problem with mere "mortal" cars...but also telling it didn't show up until after the odo had rolled over 250,000!