300SD transmission issue

[mattwestm]

I posted this elsewhere, but thought I might get some different opinions here.

I was driving to the junkyard today and got about 30 miles down the highway. I stopped for fuel and after driving away, my 300SD was not wanting to shift out of 2nd gear. Even when I manually shifted it in 3rd, it would not shift. Sometimes shifting to third, then back to drive would cause it to shift into 3rd. The car will not shift into 4th gear at all. Reverse and 1/2 gears work fine, although it takes about 3500rpm to get into 2nd.

I've only owned the car for about a week, but noticed no other transmission issues besides some slight flaring going into 3rd gear (wouldn't have bought it with tranny issues). I drove it home over 150 miles and have driven it 6-10 miles daily and have seen no issues. I'm hoping that it isn't time for a rebuild.

The fluid is clean looking, but was overfilled. I siphoned out some which did nothing. I checked the kickdown switch which is not stuck. I might try unplugging it tomorrow. I didn't see anything wrong with the bowden cable.

Should I drain and change the transmission filter? Where should I go from here?

[cooljjay]

ummm how do you shift manually into third?

The shifter has notches to go into first L and second S...

If you are flaring then that may have been the first sign...the trans was going to go..

Things that need checking

fluid/filter check when car is right at operating temp, idling in park and it should be between both notches

kick down switch, unplug the switch to see if it changes

bushings...you have 4 bushing.

Do you have a bowden cable or vacuum adjust trans or both?

linkages.

[mattwestm]

Originally Posted by cooljjay

ummm how do you shift manually into third?

The shifter has notches to go into first L and second S...

The W126 diesel has "3" and "2" positions.

On the W123, does L stand for low or first, and S for second?

This vehicle definitely has a bowden cable. Not sure about vacuum adjustment.

[tangofox007]

Originally Posted by mattwestm

On the W123, does L stand for low or first, and S for second?

Whatever the letters stand for, "L" allows operation in 1st and 2nd, "S" allows operation in 1st, 2nd & 3rd.

[mattwestm]

A leaking vacuum system shouldn't prevent the transmission from getting into a higher gear as the vacuum is only responsible for the harshness of shifting, correct?

[mattwestm]

Update: The car sat all day yesterday. I drove it again today and it shifts fine (but still a little flaring going into 3rd). What gives?