OK, I think this is an odd one - maybe someone can give me some advice.

My 82 w123 300d auto tranny is acting odd -- seems to be slipping in 3rd (4th?) on the highway sometimes, but only going uphill. Sometimes it feels like it won't engage and drops to the next gear down instead. Fluid level OK, color OK.

I talked to a local independent who I trust, who recommended a tranny service with fluid and filter. When I asked about vacuum lines maybe cracked from a recent cold snap, he said it would more likely stick in gear than slip, and that filter issues can cause all kinds of strange ills. He also advised that this is a 4 speed tranny - is that true? I've only ever had the 3 gears that I know of.

I'm ready to order up the kit (argh, christmas shipping wait!), but I wonder if it'll do the trick. After searching this fine forum, I fiddled with the kickdown switch, which seemed to be operating correctly as far as I could tell. Disconnecting it did not affect the problem.

Any ideas on what I might concern myself with appreciated.

Thanks,
Matt

I think you received good advice from your mechanic. It sounds like a fluid pickup issue, and this can be the result of a clogged filter.

The most cost-efficient thing to start off with on a transmission issue is the fluid and filter change.

It is rather costly, but I recommend Mobile 1 synthetic ATF in all these 80's vintage MBs. Keeps the transmission cleaned out and works well at all temperatures.

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

Yeah, it IS a 4 speed tranny. maybe you are starting in second, this is common with these cars. something about keeping the car from creeping forward at idle. anyway, if you drive with the pedal floored, the switch under the go pedal should put you in first, then you can count all four gears.
John

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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!

Put a quart of Trans-x in. My 240 was slipping and the additive did the trick. I also adjusted up my throttle pressure.

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My Truck.. 2007 DODGE, 5.9 Cummins, 6spd stick, 4X4. My car..1977 240D, OTHER WHEELS...1955 VW Oval window bug, European Delivery (Holland) with a 1700cc, 2 barrel, Porsche drum brakes. 1939 WILLYS Pick-up. 1967 Triumph 200cc Tiger Cub. 1976 Honda 550F 4cyl Motor Cycle.