I've got two 126 300SDs. The fuel mileage went down noticeably recently in one of the cars. I couldn't find anything wrong: quick cranking, excellent acceleration, little smoke and a smooth idle. About two months ago I had to replace one of the plastic gears in the odometer which was missing a tooth, causing the odometer to stop altogether. I still suspected an inaccurate odometer was the cause of my lower fuel mileage.

I swapped instrument clusters between the two 126s and the fuel mileage went back to normal on the first car and down on the second.

I have two used 126 speedometers for parts and know how to use a soldering iron. What parts should I be checking to repair this ailing odometer? Do I need to re-solder all of the solder joints? An other suggestions?

Thanks.

__________________
Tom Evans
69 280SE 91K (wish I still had it)
73 220D 98K
78 300D 134K
78 300D 185K
81 300SD 301K (still have)
82 300SD 321K (still have)
84 300D 268K
84 6.2 Diesel GMC Suburban 225K (a whole different story!)

I would recommend changing all three replaceable gears in that cluster. I did it on mine about 3 months ago. It worked great till recently. I suspect the large gear that is "pressed" onto it's own shaft is slipping. I am going to remove it and use a little loctite on it.

__________________
----Adam

1985 300SD 322,000

The gear I replaced is one that is supposed to turn freely on its shaft. There was an light, clear oily film on these gears. Don't know where it came from - I certainly haven't been into the odometer before.

I'll look for the large gear that needs to have good connection to its shaft and use a little Loctite.

Locktite red, Locktite blue or doesn't matter?

__________________
Tom Evans
69 280SE 91K (wish I still had it)
73 220D 98K
78 300D 134K
78 300D 185K
81 300SD 301K (still have)
82 300SD 321K (still have)
84 300D 268K
84 6.2 Diesel GMC Suburban 225K (a whole different story!)

actually I read somewhere that green loctite is supposed to be used.

Loctite 620 to be specific. It is for slip fit situations when filling a large air gap.

Just a dab will do you though.

__________________
----Adam

1985 300SD 322,000

the pressed on gear rarely if ever slips.
the problem lies in the teeth of that gear dissappearing...

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

i've replaced the gears in two 126 odometers so far.

www.odometergears.com in Newport News, VA sells the gears and you can buy them in a set. i wouldn't bother replacing just one, do all 3 while your in there so you don't have to do it again.

the guys at odometergears.com are totally helpful. just ask them

__________________
R Martin
Dallas, TX (Addison)

86 560SEL, 128K

VSTech,

Could you elaborate on your comment that "the problem lies in the teeth of that gear dissappearing..."? I've already replaced the gear with the missing tooth. Since I have a full set of gears, should I simply replace them all? Do you think something is binding in the odometer?

__________________
Tom Evans
69 280SE 91K (wish I still had it)
73 220D 98K
78 300D 134K
78 300D 185K
81 300SD 301K (still have)
82 300SD 321K (still have)
84 300D 268K
84 6.2 Diesel GMC Suburban 225K (a whole different story!)