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.

__________________
Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

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

__________________
1977 Mercedes 240D. 4-speed transmission. Windows, A/C, and sunroof: all manual. Medium Red. 204K miles.
1988 Subaru GL wagon. Dual range 5-speed 4X4. Daily driver w/ twin parts car.
1994 Subaru Loyale wagon. 5-speed 4x4
1966 International 3/4 ton 4X4 truck. Ooh yeah!
1952 Ferguson TO-35 farm tractor.
1984 Snapper rear engine riding mower. Just like Forest Gump.
1988 Nimble 20 sail boat
--Older stuff is built better--

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!

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Look here...

__________________
1977 Mercedes 240D. 4-speed transmission. Windows, A/C, and sunroof: all manual. Medium Red. 204K miles.
1988 Subaru GL wagon. Dual range 5-speed 4X4. Daily driver w/ twin parts car.
1994 Subaru Loyale wagon. 5-speed 4x4
1966 International 3/4 ton 4X4 truck. Ooh yeah!
1952 Ferguson TO-35 farm tractor.
1984 Snapper rear engine riding mower. Just like Forest Gump.
1988 Nimble 20 sail boat
--Older stuff is built better--

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!