Hello all, new to the forum. I have spent the last month reading and reading. I have found abundant information regarding the transmissions in these vehicles however, I have not found an example of my specific problem.
I have a newly acquired 1983 300SD whose performance has been amazing. As previously stated however, it starts in second gear. It will start in first if you manually move the shift lever into L and then it will only shift into second at 3800 rpm in any accelerator pedal position. The number on the trans case is 722.303. I have checked all vacuum related components and I am receiving 13lbs of vacuum at the modulator, it drops to zero at full throttle. When lengthened/loosened, the bowden cable allows the transmission to shift earlier and when tightened/shortened, it shifts later in the rpm band. With bowden cable unhooked, the car still starts in second gear and changes through the gears very rapidly. The fluid and filter are new as well as the fluid level being correct. There is a small leak coming from the B2 case. Besides checking the internal pressure of the transmission, which I will be doing in a couple days, where/what should I be looking towards to solve this dilemma? I thought B2 piston initially, but first gear works when manually pulled into it. The kickdown switch is operable and functions as it should. What would cause this 722.303 to start in second by default instead of first when the accelerator is depressed? Any or all suggestions would be greatly appreciated.

most of the MB diesel transmissions are designed to start in second. they only drop into first if you shift into L or put the pedal on the floor from a dead stop

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1981 NA 300D 310k miles

It should shift back to first gear upon take off, that is controlled by the bowden cable. Normally when you press the accelerator pedal the linkage pulls first on the bowden cable (to shift back), then it actuates the IP lever. If the transmission does not shift back, first check if the linkage is adjusted to specs, it is in the FSM:

30 Acceleration Control System - OM617 turbo

There 30-300, section C, type 126.120

The shift back to first is obtained by disengaging the B1 brake band, by relieving pressure on the B1 piston. So if the linkage is OK, it can be the B1 piston or the valve that controls it, see here:

Transmission Experts: Please help - Benzworld.org - Mercedes-Benz Discussion Forum

Sometimes it is as simple as changing the transmission oil and filter, it should be done every 35,000-40,000 miles or so.

it could be the fluid leak in the b2 case. you should pull it and replace the o-ring. also replace the piston and sleeve if you don't know the condition of the trans.
another possibility is the transmission was pulled from a gasser, and it's designed to start in 2nd. if you pull the entire trans identification number, perhaps Whunter can search it out and verify what car it came from.

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1987 190D 2.5Turbo
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1987 300TD
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Thank you sooo much. This has given me more areas to inspect. The bowden cable seems to be in proper adjustment along with the linkage, however; the cable feels great when you pull on it until the last ~.5in of travel where it feels very spongy... I will soon check the pressure just to eliminate (hopefully) that being the cause of the the B1 band not disengaging. I will drop the pan and inspect why the bowden cable feels spongy as well as checking the functionality of valve 17 in the valve body. Again, thank you very much. If there are any items I can disregard in checking or any more possibilities, please share. Thank you! Thank you!