Hello, this is my first post on this forum but this problem is driving me nuts!

I have a 83 300sd with a 722.3 transmission

When I first got the vehicle I was experiencing a bad flare between 2-3. Finally after it drove me nuts I decided I was going to install a shift kit. After installing the shift kit, I found that i found that the flare got worse! This time I couldn't even get the tranny into 3rd gear.

After much troubleshooting I decided I would just swap the tranny, to verify that I used the right tranny, I matched the part number for the tranny casing and the stamped number on the valve body.

Before putting in the new transmission I put in the updated green modulator (new off of my old tranny), changed the k1 valve spring, resealed the transmission (according to a mb Manuel) and insured that the transmission was still good (look for wear on brake bands, gears and pump)

Finally after installing the new transmission I found THE EXACT SAME PROBLEM. I tried adjusting Bowden cable, disconnecting the kickdown solenoid, I disconnected vaccum to no avail... The only thing I can find is that if I hammer down on the accelerator in drive the tranny will try searching for a gear but then just go back to flariing. If it put it in low it will drive in 2nd.

I'm at my wit's end and I have no idea what to do next

Did you try adjusting the vacuum modulator?

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1990 190E 3.0L

Hmm, well I unplugged the modulator and I still have flares, from what I understand that should rule out vacuum entirely. Unless you could tighten the adjustment on the modulator too tight, I did do that after I finished the transmission because I wanted firmer shifts.