Hi friends. I am seeking an advice for a problem I had recently with my 1991 350SD Turbodiesel sedan with automatic transmission. Upon the routinary short driving that I do daily, I noticed a jerky (not smooth) shift from first to second gear the day I had the problem. I drove about 5-6 miles, and all of the sudden when I was returning to my office, the transmission will not shift under any circunstance to the second gear. The day before, I did a 75 miles trip without any symptoms. Previous work, was that I replace the radiator, with a loss of about 3-4 ounces of transmission fluid (not replaced). The car ran at a higher temperature than normal, at the upper white line of the gauge (around 10 in a clock) but never into the red zone, when the upper plastic cover of the radiator cracked. I added ATF to the appropriate level, but the condition is still present.

Any ideas? Does it seems like an overhaul for the AT with 94K miles on it? What should be my first step?

Thank you for the opportunity.