In addition to the aforementioned slipping malady, I also wanted to mention to the group and solicit comments on what seems to me to be an odd phenomenon of the transmission possibly not shifting into top gear. It seems like the engine revs high and sounds loud at cruise speed (65-70 mph); however, it is a non-turbo 5 cylinder diesel. All engine indications, i.e., temperature, are normal.
You should be able to count the shifts from start. Also, the service manual should have the correct engine RPM for a given highway speed.
I'm guessing that you don't have a tachometer. If you did, then you could tell what speed the engine is running at highway speeds. That should be enough for you to be able to tell if it really is in high gear or not. My 84 300D (turbo model) runs at 3000 rpms at 70. Thats pretty high, but not as high as it does when it is in 3rd at that speed.
I had a similar problem with mine recently. The throttle position cable on mine is wore out and got stuck at full throttle once. This kept it from shifting into high gear, until I unplugged the kick down solenoid under the pedal. Sometimes when the cable sticks (after full throttle acceleration) then it has trouble getting into high gear. To remedy this, I shift to neutral, then back into drive at speed. When the transmission reengages, it will go into high gear. You might want to try unplugging the kick down solenoid to see if that helps.
I was thinking about the vacuum modulator instruction I gave you... you have to turn in clockwise to reduce the vacuum assist... which will make the shift firmer. Counter clockwise will open up the vacuum for more soft and also less pressure.
Doug also got a good tip too... about the kickdown.
MB Tranny tech can quickly diagnose the problem but the problem is alot of them just want $2500+ rather than adjusting for you...
would if I could count that high...
But seriously, even if I knew the RPMs for fourth gear, I do not have a tachometer to check it.
I will try that and check it--thanks!
I'm going to try that, thanks very much.
And thanks for the info about the modulator, as I am going to adjust that today.
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