People Hi again,

The autobox on the camel (a 200Tdi 1993 evented  Discovery converted to
autobox) has started developing a problem with its high gears.

It appears that the four gear is reluctant to engage and that third gear is
stuck or slipping.

The vehicle runs nicely at fourth gear with around 3000 rpm at 120 Kph.  But
after a while third gear changes by slipping downwards at the rpm range and
the engine runs at 4000 rpm at 100 Kph with the gearbox not wishing to
change up to fourth gear.

It also has a general feel like a manual gearbox with a very worn clutch.

Gearchange from first to second and second to third is OK.

When the "slipping" and stuck gearchange from third to fourth (not happening
at all that is) is happening the car also has problems with its reverse
gear.
Meaning that when I stop and wish to reverse the engine revs a lot for the
car to actually move back and it also has the "slipping clutch" feel to it.

-------

The autobox was struck with a contaminated ATF problem some years ago which
led to the ATF burning and also chaffing the friction plates.  The ATF was
changed three times, an antislip additive was added and it worked nicely for
about two years.  Then the first gear got stuck (no change to second gear or
upwards). Gearbox was removed and checked.
Friction plates were found to be OK and a spring in the vavles housing was
found to be broken in three pieces.  After that the autobox was re-installed
with almost no problems apart from a reluctance to engage first gear
immediately when very cold and a somewhat bumpy change from first to second
gear.

I have bought a nice secondhand autobox from a 300Tdi Discovery (complete
with torque converter) so most probably I will be replacing the faulty unit
altogether.

But it would be very helpful to know what is the most probably cause for the
"slipping" third gear, stuck third to fourth gear change and "slipping"
reverse problem (all of them not happening until the car is hot and not
happening all the time).

One more thing that was happening was that the kickdown appears to have been
engaging very easily.  When on fourth gear and at around 130 kph if I
pressed the accelerator pedal more ( in order to increase speed) the
kickdown would engage and drop down to third gear (with 4500 rpm at the
engine).  Is this something that can be addressed to by shortening the
kickdown cable's travel (effectively increasing the accelerator pedal's
travel without engaging kick down) and would this be a reason why the third
to fourth gearchange has started to malfunction and the third gear friction
plates most probably got worn out?

Sorry for the big posting and lots of questions but autoboxes are unknown
land and your input is always appreciated and extremely helpful into getting
into grips with things.

Take care and happy New Year.
Pantelis