I have all the related problems of a maladjusted vacuum system, which I am going to address next weekend, with the help of this forum, but I am unsure if this is also related. My transmission will not shift into high gear until I am going 65 mph, regardless of throttle position. I do not want to drive it due to the high rpm's which I'm sure diesels are against. I have to work this weekend so I will be unable to work on it this weekend, but I was just wondering what you guys think. Could it be a throttle linkage problem?

P.S. the car is a 1981 300D.

What's the 1-2 and 2-3 shift points?

the 1-2 shift is early at around 15 mph, and the 2-3 is around 35-40 mpg. The shifts are hard at part throttle but smooth out at full throttle.

The 2-3 is at 35-40 with very little throttle? If so, then it's also very late.

I thought these transmissions usually shifted at certain setpoints, and the vacuum system adjusted the harshness. I realize throttle position will affect when the car shifts also, but this car shifts the same regardless of throttle position.

sure thing