[modern] 90 Sov. Transmission Shifting Poorly When Warm

Hi All,

  While waiting for the manual to arrive for my 90 XJ6 Sov. 109k, new

bearings for the diff sitting on the garage floor, the transmission has
started to do something awful. I have only been driving the car once a week
or so until I can get the diff fixed and all the other maintenance done.

  Right after a cold start, the transmission shifts OK 1-2, 2-3, 3-4.

As the car warms up, about 5 miles, shifting gets sloppy. Shifting from
1-2, 2-3 feels like I’m letting off the accelerator for a second. Later,
when the car warms up to temp, shifting 1-2, 2-3 also develops a “thump”, a
hard shift. Ive seen posts on the list from you with these cars having 150K
and 180K miles, so its very discouraging for a car with 109k.

  The fluid does not appear to be low.  I check after driving for a

while (engine idle, trans in park): the first time I pull the stick out,
its dry. I put the stick back in, pull it out, and its very near the top
“HOT” mark. The fluid is old (planned on replacing it after the bearning
job), but not excessively burned. There’s no evidence that the car
overheated, but its an old cat and I don’t have any history on it.

  It does not sound like a inexpensive fix, but anyone have similar

experiences with a good outcome?

Regards,
Mike

Mike,
I would pull the pan and check the filter and magnets.

The filter is just a screen, and you can wash it out
and dry it, but the correct filter has a spout
out the bottom…the incorrect filter has a hole
on the side.

The magnets will likely have a bit of fuzz on them,
this is normal.

I would suspect a problem from the trans sitting
and not a serious mechanical problem.
No trans alarms on the dash?

The 1990 transmission is electronic operated.
It has its own throttle position sensor built
into the engine throttle position sensor, it has a speed
sensor on the tail shaft (like the abs sensors), a pressure
reporting sensor, and the gear change solenoids.
The transmission ecu DOES output an ignition timing retard
signal during shifts to the main engine ecu.
If the transmission ecu is getting the wrong signals
from the throttle, the pressure, the speed, etc,
shifting can go wacko.
Gummed up valves can also cause problems, and they can change
with temperatures.
After checking the pan and filter, try some synthetic trans fluid,
the stuff for the new cars.

Even old fluid should not be burnt or dark…

Brett
1990 XJ6>

Hi All,

  While waiting for the manual to arrive for my 90 XJ6 

Sov. 109k, new
bearings for the diff sitting on the garage floor, the
transmission has
started to do something awful. I have only been driving the
car once a week
or so until I can get the diff fixed and all the other
maintenance done.

  Right after a cold start, the transmission shifts OK 

1-2, 2-3, 3-4.
As the car warms up, about 5 miles, shifting gets sloppy.
Shifting from
1-2, 2-3 feels like I’m letting off the accelerator for a
second. Later,
when the car warms up to temp, shifting 1-2, 2-3 also
develops a “thump”, a
hard shift. Ive seen posts on the list from you with these
cars having 150K
and 180K miles, so its very discouraging for a car with 109k.

  The fluid does not appear to be low.  I check after 

driving for a
while (engine idle, trans in park): the first time I pull
the stick out,
its dry. I put the stick back in, pull it out, and its very
near the top
“HOT” mark. The fluid is old (planned on replacing it
after the bearning
job), but not excessively burned. There’s no evidence that the car
overheated, but its an old cat and I don’t have any history on it.

  It does not sound like a inexpensive fix, but anyone 

have similar
experiences with a good outcome?

Regards,
Mike

BRetts right on this one - I would give it a filter & fluid change-
ELECTRONIC VALVE BODIES REQUIRE?WORK BETTER WITH THE NEWER SPEC FLUIDS
BECAUSE THE SOLENOIDS WORK BETTER WITH IMRPROVED LUBRICITY OF THE
SEMI_SYNTHETIC SPEC FLUID. IE DEX III & MERCON V. I would personally flush
it multiple times with cheap costco DEXIII $12.00/ case fluif - or get it
reversed flushed - to clean the converter… The I would add a bottle of
Lubguard OR switch to pure synthetic fluid … A solenoid may be acting up as
well. Finally, many of the new valve bodies are made of aluminum VS case
iron - aluminum loves to embed particles & get sticky - the rule is 1)
cleanliness is next to godliness with electronic valves bodies & 2) frequent
fluid changes & 3) high quality fluid are essential …

BIGGY

Ok all this talk of trans. problems has me thinking of my 103k mile 90
VDP that is just sitting waiting for my attention.

I have not had the time to spend investigating it’s many problems. But
the most serious of it’s short comings is that it only moves in reverse.
I bought it this way when I also bought my 88 XJ6. The 88 is now my
daily driver but in time I want to get the 90 on the road. Quick checks
I’ve done on the trans. shows that it is full of red fluid and that it
will try to move forward if on flat ground. Rev. is solid and the
converter seems to have good “stall speed” in rev. I checked the
trans. relay under the dash on the right side and it is operating. Then
I ran out of time. I have a wiring diagram for this car but no factory
manual yet. One of my local Jag. parts suppliers tells me this ZF24 is
a strong trans. with few internal problems and that the problem may well
be electrical. I do not get a trans. dash light warning. I’ve read some
of the posts regarding accumulator spring failure but assume that this
would cause harsh apply and shifts but that the clutches would still
engage. Could a sticking or failed solenoid cause no forward drive
without turning on the light? (it does come on if I disconnect the relay)
Any thoughts would be appreciated.

Matt
88XJ6
90VDP
77MGB
87F250
98E350

R Mahoney wrote:>BRetts right on this one - I would give it a filter & fluid change-

ELECTRONIC VALVE BODIES REQUIRE?WORK BETTER WITH THE NEWER SPEC FLUIDS
BECAUSE THE SOLENOIDS WORK BETTER WITH IMRPROVED LUBRICITY OF THE
SEMI_SYNTHETIC SPEC FLUID. IE DEX III & MERCON V. I would personally flush
it multiple times with cheap costco DEXIII $12.00/ case fluif - or get it
reversed flushed - to clean the converter… The I would add a bottle of
Lubguard OR switch to pure synthetic fluid … A solenoid may be acting up as
well. Finally, many of the new valve bodies are made of aluminum VS case
iron - aluminum loves to embed particles & get sticky - the rule is 1)
cleanliness is next to godliness with electronic valves bodies & 2) frequent
fluid changes & 3) high quality fluid are essential …

BIGGY

A bad EPC solenoid on many domestics will not give you any forward gears…
Im not sure of the 4HP24 - the thing is bullet proof generally - if it has
been maintained - however, if you bought it that way, chances are that the
other dude changed the fluid as a desperate attempt to solve his no-D
perdicament - IE the thing HAD toasted fluid in it … However, your best bet
is to trouble shoot this - IE whatever the Jag manual calls out OR call
Jaggi in Houston & ask him for some ideas …if your lucky - its a solenoid -
if your not lucky - you can pickup a used one & slap it in - because of
their robustness - they really dont fetch too much of a premium because
there are lots of them around … IE supply & demand are weighing in your
favor

BIGGY

Thanks!-----Original Message-----
From: owner-modern@jag-lovers.org [mailto:owner-modern@jag-lovers.org]On
Behalf Of R Mahoney
Sent: Saturday, April 06, 2002 8:43 AM
To: brett.gazdzinski@wcom.com; ‘Mike Pukmel’; modern@jag-lovers.org
Subject: Re: [modern] 90 Sov. Transmission Shifting Poorly When Warm

BRetts right on this one - I would give it a filter & fluid change-
ELECTRONIC VALVE BODIES REQUIRE?WORK BETTER WITH THE NEWER SPEC FLUIDS
BECAUSE THE SOLENOIDS WORK BETTER WITH IMRPROVED LUBRICITY OF THE
SEMI_SYNTHETIC SPEC FLUID. IE DEX III & MERCON V. I would personally flush
it multiple times with cheap costco DEXIII $12.00/ case fluif - or get it
reversed flushed - to clean the converter… The I would add a bottle of
Lubguard OR switch to pure synthetic fluid … A solenoid may be acting up as
well. Finally, many of the new valve bodies are made of aluminum VS case
iron - aluminum loves to embed particles & get sticky - the rule is 1)
cleanliness is next to godliness with electronic valves bodies & 2) frequent
fluid changes & 3) high quality fluid are essential …

BIGGY

Brett,

Yes, I planned on taking off the pan and doing a fluid and screen change
soon.

There are no alarms on the dash. The car DID sit for about 1 year prior to
my purchasing it.

I just took it out for a run tonight, and got it up to 95mpb. No shudders
or shakes. Starting at about 40mph I put it in “passing gear”, i.e.
kickdown, and it downshifted smoothly, and ran up to 95 and stayed there
with no problems. Its just when Im shifting from 1-2 2-3 at low
acceleration.

The fluid is definitely OLD but not burned. Ill do another post when the
pan is off.

On a related aside, on the top of the coolant expansion tank, around the
filler cap, theres some crust. It looks like coolant spatter at one time
(or more than one time). I noticed this on a some pictured of a few Jags
on Ebay. Does this indicate that the car overheated at one time?
Overheating will affect the transmission too, right?

Since Ive had the car, I have not seen any fluid come out of the expansion
tank.

Thanks Again,
Mike-----Original Message-----
From: owner-modern@jag-lovers.org [mailto:owner-modern@jag-lovers.org]On
Behalf Of Brett Gazdzinski
Sent: Friday, April 05, 2002 11:29 PM
To: ‘Mike Pukmel’; modern@jag-lovers.org
Subject: RE: [modern] 90 Sov. Transmission Shifting Poorly When Warm

Mike,
I would pull the pan and check the filter and magnets.

The filter is just a screen, and you can wash it out
and dry it, but the correct filter has a spout
out the bottom…the incorrect filter has a hole
on the side.

The magnets will likely have a bit of fuzz on them,
this is normal.

I would suspect a problem from the trans sitting
and not a serious mechanical problem.
No trans alarms on the dash?

The 1990 transmission is electronic operated.
It has its own throttle position sensor built
into the engine throttle position sensor, it has a speed
sensor on the tail shaft (like the abs sensors), a pressure
reporting sensor, and the gear change solenoids.
The transmission ecu DOES output an ignition timing retard
signal during shifts to the main engine ecu.
If the transmission ecu is getting the wrong signals
from the throttle, the pressure, the speed, etc,
shifting can go wacko.
Gummed up valves can also cause problems, and they can change
with temperatures.
After checking the pan and filter, try some synthetic trans fluid,
the stuff for the new cars.

Even old fluid should not be burnt or dark…

Brett
1990 XJ6

Hi All,

  While waiting for the manual to arrive for my 90 XJ6

Sov. 109k, new
bearings for the diff sitting on the garage floor, the
transmission has
started to do something awful. I have only been driving the
car once a week
or so until I can get the diff fixed and all the other
maintenance done.

  Right after a cold start, the transmission shifts OK

1-2, 2-3, 3-4.
As the car warms up, about 5 miles, shifting gets sloppy.
Shifting from
1-2, 2-3 feels like I’m letting off the accelerator for a
second. Later,
when the car warms up to temp, shifting 1-2, 2-3 also
develops a “thump”, a
hard shift. Ive seen posts on the list from you with these
cars having 150K
and 180K miles, so its very discouraging for a car with 109k.

  The fluid does not appear to be low.  I check after

driving for a
while (engine idle, trans in park): the first time I pull
the stick out,
its dry. I put the stick back in, pull it out, and its very
near the top
“HOT” mark. The fluid is old (planned on replacing it
after the bearning
job), but not excessively burned. There’s no evidence that the car
overheated, but its an old cat and I don’t have any history on it.

  It does not sound like a inexpensive fix, but anyone

have similar
experiences with a good outcome?

Regards,
Mike

Mike,

That is normal.
A new cap may help, but the caps are vented and
may weep a bit…

Its not a sign of overheating.

Brett
1990 XJ6> On a related aside, on the top of the coolant expansion tank,

around the
filler cap, theres some crust. It looks like coolant spatter
at one time
(or more than one time). I noticed this on a some pictured
of a few Jags
on Ebay. Does this indicate that the car overheated at one time?
Overheating will affect the transmission too, right?

Since Ive had the car, I have not seen any fluid come out of
the expansion
tank.

Thanks Again,
Mike
-----Original Message-----
From: owner-modern@jag-lovers.org
[mailto:owner-modern@jag-lovers.org]On
Behalf Of Brett Gazdzinski
Sent: Friday, April 05, 2002 11:29 PM
To: ‘Mike Pukmel’; modern@jag-lovers.org
Subject: RE: [modern] 90 Sov. Transmission Shifting Poorly When Warm

Mike,
I would pull the pan and check the filter and magnets.

The filter is just a screen, and you can wash it out
and dry it, but the correct filter has a spout
out the bottom…the incorrect filter has a hole
on the side.

The magnets will likely have a bit of fuzz on them,
this is normal.

I would suspect a problem from the trans sitting
and not a serious mechanical problem.
No trans alarms on the dash?

The 1990 transmission is electronic operated.
It has its own throttle position sensor built
into the engine throttle position sensor, it has a speed
sensor on the tail shaft (like the abs sensors), a pressure
reporting sensor, and the gear change solenoids.
The transmission ecu DOES output an ignition timing retard
signal during shifts to the main engine ecu.
If the transmission ecu is getting the wrong signals
from the throttle, the pressure, the speed, etc,
shifting can go wacko.
Gummed up valves can also cause problems, and they can change
with temperatures.
After checking the pan and filter, try some synthetic trans fluid,
the stuff for the new cars.

Even old fluid should not be burnt or dark…

Brett
1990 XJ6

Hi All,

  While waiting for the manual to arrive for my 90 XJ6

Sov. 109k, new
bearings for the diff sitting on the garage floor, the
transmission has
started to do something awful. I have only been driving the
car once a week
or so until I can get the diff fixed and all the other
maintenance done.

  Right after a cold start, the transmission shifts OK

1-2, 2-3, 3-4.
As the car warms up, about 5 miles, shifting gets sloppy.
Shifting from
1-2, 2-3 feels like I’m letting off the accelerator for a
second. Later,
when the car warms up to temp, shifting 1-2, 2-3 also
develops a “thump”, a
hard shift. Ive seen posts on the list from you with these
cars having 150K
and 180K miles, so its very discouraging for a car with 109k.

  The fluid does not appear to be low.  I check after

driving for a
while (engine idle, trans in park): the first time I pull
the stick out,
its dry. I put the stick back in, pull it out, and its very
near the top
“HOT” mark. The fluid is old (planned on replacing it
after the bearning
job), but not excessively burned. There’s no evidence that the car
overheated, but its an old cat and I don’t have any history on it.

  It does not sound like a inexpensive fix, but anyone

have similar
experiences with a good outcome?

Regards,
Mike