300D Transmission Slipping (2)

wrote:

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.

wrote:

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 will try that and check it--thanks!

wrote:

 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 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...

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.