300D Transmission Slipping

No... simply changing the fluid and filter might help. When I got my car, it
was slipping on takeoff... occasional. After fluid change and filter, it
hasn't slipped since then. The tranny has 209,000 miles now.

I use Valvoline Dextron ATF or Pennzoil Multi-Vehicle ATF. For the 5 speed
transmission, I use Amsoil synthetic Universal ATF.

I would have thought this too, but the transmission fluid and filter
were just changed this Fall after I had the engine rebuilt.  So the
fluid is new, and transmission slipping.  What are other fixes for
this short of a rebuilt trans.?

Did he do a full drain including the torque converter? If not, then that is
not enough... what I do on mine... without draining the torque converter is
to drain, fill, drive 10 miles and repeat 3 time.

On the third time, I then change the fluid.

What gear is it slipping? Only when starting to move? Or certain gear? How
many miles on the tranny?

Tiger:

I was contemplating doing the "drain and fill" method, but am not sure
if I want to do that if I am going to convert to synthetic trans
fluid.  Then on the other hand, maybe I don't want to switch to
Synth.  During the engine overhaul, the transmission fluid was drained
twice (once to change, another because they pinched the gasket upon
installation).  However, I do not know if they drained the torque
converter--I would like to think they did, bur not being certain, I
would have to say, maybe not.  The transmission is slipping in all
gears.

Randall

P.S. Only 218,000 miles on transmission.

218,000 miles and you didn't spring for a rebuilt tranny while your engine
is out? Yeah, the engine cost a fortune...

Slipping in all gear is not possible unless catastrophic failure. Usually it
is slipping upon start that the engine revs and then tranny jerk...

Have you tried adjusting your vacuum modulator? Adjust it counter clockwise
for less vacuum assist... and more firm gear. Improper asjustment cause
slipping in all gears.

Or from an old engine to new rebuilt engine is enough to cause slipping
because new engine got more vacuum pressure.

Other possibility is improper tranny throttle cable adjustment. It should be
slightly loose on idle position... just follow the cable from your tranny.
it should be loose a bit.

Don't waste your money on synthetic.

Tiger.  OK, forget synthetic.  I was about ready to take that decision
anyway, after reading all the posts here about it.

No, I didn't think about a rebuilt transmission at the time that the
engine rebuild became necessary, because I was somewhat in shock from
the notion of needing an engine rebuild at just over 200K miles, and
insofar as the transmission was not slipping or showing any signs of
needing maintenance at that point, the thought of replacing the
transmission never even occurred to me.

Your point about the vacuum adjustment seems to be the most plausible,
although I will certainly check the throttle cable adjustment.  The
transmission does slip as it goes through each gear, which makes this
seem more than a likelihood.