Thanks for the input. I now know that I'm not getting 4th gear for sure. Any more insights are appreciated.

What I've done so far: fluid level ok, disconnected the kick down switch, disconnected the transmission vac line - still no 4th

Time for fresh ATF fluid and filter change...

Any possibility that your shifter lever / linkage is messed up, and when you think you have selected "D" you are really in "3"? That would be a nice simple and probably cheap fix...

Vacuum is used to control the soft/hard nature of the shifting.

There is a cable from the transmission to the throttle linkage (aka Bowden cable) which controls the shift timing (how early/late the transmission will up-shift depending on throttle position). It is under the intake manifold close to the oil filter canister, real pain in the but to reach on an OM603.

I don't think that either of these is the issue in your case.

I'll change the ATF and filter to rule it out. My shift lever is firm, I will have to check the linkage though.

I didn't get any positive result when I messed with the vacuum and bowden cable, I don't think it's the issue neither.


Do you have any info regarding the kick down solenoid (the one attached to the transmission)? I have read some threads about it but the TS doesn't report back in each of the posts I read, so they're inconclusive.

I haven't updated this in a while. I did an atf/filter change and I got my 4th gear back.

However, I'm still having issues. When accelerating with about 1/3 pedal, I have to let go for a second or two before it shifts to 4th. And when in 4th @ 50mph, the rev would go up (flaring?) if I give it more than 1/4 pedal. It doesn't happen when I speed up very gradually with a very light touch on the accelerator.

Sounds like the clutches are slipping???

This won't help with the flaring, and I'm probably wrong anyway, but:

When I got my '84 W123, it wouldn't shift in 4th either. The only way to make it shift into 4th was either accelerating very slowly, or letting go of the throttle and resuming once I was above 40mph or so, to make it shift up.

Reason? Bowden cable too tight. Loosened it up to where it has a tiny little bit of slack, and it shifts at much better points now and gave me 4th gear back without a problem.

I'm not a mechanic and I don't know much, but you could give it a try. The bowden cable is easily adjusted by hand. If it doesn't work, you can adjust it back to where it was, no harm done, but at the very least you can rule it out.

It feels like it, but I'm not very sure. Do you think changing the K2 spring will help?

Thanks, I'll try to adjust the bowden cable again and see if I'll have better shifting.

Trying to diagnose my new 82 300d - since search brought me here, thought I'd ask. I'm not familiar with what to listen/feel for with the tranny and I've already fixed some clunking in the downshift to 1st by finding a cracked vacuum line.

When I'm on highway doing 65-70 my tach reads somewhere around 30, maybe tad under. Does this mean I'm getting 4th? I can't tell if I'm feeling all the shifts that I should.

That car was geared for the 55mph NMSL, 3000rpm at 70mph sounds right.

X2

70 MPH at 3000rpm....that's what my SDL turns.

ok, thanks!