automatic transmission 2.5 V6 Rover 75

[Chris varming]

This subject may have been on the agenda before, BUT I have suddenly encountered the following: Transmission is OK when I start the engine, goes forward and reverse as it used to do. After a few minutes it simply does not engange in any of the gears. When the engine has cooled down it works again for a few minutes. I have changed the transmission oil as I thought that was the problem, but no luck. Any ideas? Regards, Chris Varming

[vitesse]

Hi Doc, odd problem, sounds like an electrical issue to me, some sort of communication failure between the ECM (main ECU) and the Jatco ECU perhaps. I remember an issue I had with one of my SD1s, one of the gauges would only work when cold as when the PCB (printed circuit board) expanded connection was lost - cooled down and back to normal. Ordered a new circuit board from Rimmer’s and all was well.

Do you have the diagnostic programme Toaf? That might provide some clues although it isn’t nearly as comprehensive as a Rover T4.

Keep well

[SD1too]

Hello Chris,

As you haven't reported ERR or EP displayed in the instrument pack, it's worth checking the fluid level (possibly pressure related due to relationship with temperature).

When you changed the fluid did you ...

• Use N402 spec. fluid?
• Use your multimeter to monitor fluid temperature at the round multi-pin connector?
• Use the level checking plug as described in the manual?

Simon

[Chris varming]

Originally Posted by vitesse

Hi Doc, odd problem, sounds like an electrical issue to me, some sort of communication failure between the ECM (main ECU) and the Jatco ECU perhaps. I remember an issue I had with one of my SD1s, one of the gauges would only work when cold as when the PCB (printed circuit board) expanded connection was lost - cooled down and back to normal. Ordered a new circuit board from Rimmer’s and all was well.

Do you have the diagnostic programme Toaf? That might provide some clues although it isn’t nearly as comprehensive as a Rover T4.

Keep well

I have tested the automatic transmisson with the TOAF and there was no errors found on the Jatco module. Hmmm...

Originally Posted by SD1too

Hello Chris,

As you haven't reported ERR or EP displayed in the instrument pack, it's worth checking the fluid level (possibly pressure related due to relationship with temperature).

When you changed the fluid did you ...

• Use N402 spec. fluid?
• Use your multimeter to monitor fluid temperature at the round multi-pin connector?
• Use the level checking plug as described in the manual?

Simon

I have used the Castrol Transmax ATF recommended by Landrover specialist in Denmark.
Using the multimeter I have not done.
I went through the procedures as described in the manual.
Driving the Rover today I heard a little noice comming from the gearbox, this was only heard when there was no power on the transmission. When the temp. reached 75 on the instrument pack the problems started and there was no power from the gearbox. Stopped the engine for 4 minutes, started again and in 2nd gear I managed to drive about 200 meters, then the RPM went up and no power. I managed to get home after 4 attempts.
Have you any indication of what that could be?
Kindest regards, Christian Varming

[SD1too]

Originally Posted by Chris varming

I have used the Castrol Transmax ATF ...

Hi Chris,

Thanks for your reply. I've had a look at the Castrol website and there are six varieties of this product and none of them meets MG Rover's N402 specification. There are many fluids which do and using one of those removes any possibility of incompatibility.

Having said that, I would be very surprised if that is the reason for the loss of drive you are experiencing.

Originally Posted by Chris varming

Have you any indication of what that could be?

I suspect low fluid level but in any case it certainly needs checking, bearing in mind the absence of fault codes and the fact that the symptoms are temperature dependent. The recommended fluid temperature is between 35 and 40˚C which is uncomfortably hot to the hand so do you think it's possible that when you changed the fluid it was at a much lower temperature than this?

The connector you need for temperature measurement is C0243 which is black, barrel shaped, has 18 pins and is located beside the battery. You're looking for a resistance reading between pins 7 & 8 of 1.7kΩ (35˚C) to 1.16kΩ (40˚C). Further information can be found with a forum search.

The only reported problem with the JATCO gearbox is a cracked reverse piston and that can result in loss of drive and particularly reverse gear but make sure that your fluid level is correct before considering that.

Simon

[Chris varming]

Just want to let you know that I've not been able to find out what actually is wrong with the automatic transmission. Every morning I start the car and it runs perfectly for about 1 km then suddenly the power is gone and I can only limp home as described earlier. Guess I'll have to find someone who can swap the transmission, (I have a 75 with a bad engine but a good transmission - and a 75 with a bad transmission but a good engine) Thanks for your reply. Chris Varming

[Zsoltipapa]

hi Chris,
just bought 2002 2.5 automatic from an old man (195.000 km), he exchanged all parts needed, had tons of invoices. perfect looking car, stayed indoors.
After driving 500 km I had the same symptoms, slipping gears, I stopped, start again, drove 2km, same, drove to next mechanic.
Transmission works ONLY when cold, car warms up, revs up, no drive.
Transmission oil was changed 5000 km ago, 2 solenoids as well.
Mechanic wants transmission oil change.
What a hell is this ?
Previous owner says there is a magnetic switch inside gearbox that can fail causing this,
I go mad, I want to love this car....
Please help me,
Zsolt

[SD1too]

Originally Posted by Zsoltipapa

Transmission works ONLY when cold, car warms up, revs up, no drive.
Transmission oil was changed 5000 km ago ...
Mechanic wants transmission oil change.
What a hell is this ?

Hello Zsolt,

You ask: "What the hell is this"? The answer is that it's a very strange fault that we have not come across before.

Do you see 'EP' in the gear selector display instead of 'D'?

My first thought is linked to the fluid change 3,000 miles ago. When the fluid reaches normal operating temperature it becomes less viscous or thinner. That can lower fluid pressure, especially if the level is low. Also, use of fluid not meeting N402 specification might affect pressure when hot. If it is not known which fluid was used for the change 3,000 miles ago then I agree with your mechanic's comment.

My second thought is that you may have a faulty fluid temperature sensor. However this is very unlikely as no-one else has reported this.

Automatic transmission faults are nearly always related to fluid level or engine tune.

Simon

[Zsoltipapa]

hi Simon,

thanks for fast reply.
car showed EP yes, and oil was right spec.and changed with pressure based professional machine, but was black when we checked now (instead of red).
Can you imagine that the car was flawless for 3000 miles then broke down,we changed trans oil, and it drives again?
(we deal with american cars here and the Middle East, and if this happens in case of old cars, we put some additive ,done, haha)
interestingly people here suggest electronic failure and mechanic failure like torque converter......
to be honest, car was very slow when floored at start, diag shows 1471/72,VIS motor, but owner said he exchanged them,I guess its other issue.....
what do you think?
I follow your work its great,I chose this rover after a wonderful 2003 Mini Cooper as a daily here....
Regards,Zsolt

[SD1too]

Originally Posted by Zsoltipapa

... we changed trans oil, and it drives again?

So have you solved that fault?

Originally Posted by Zsoltipapa

... car was very slow when floored at start, diag shows 1471/72,VIS motor, but owner said he exchanged them, I guess its other issue.....
what do you think?

Slide out the balance flap behind the actuator (motor). They can stick half open.
Check that the power linkage moves without excessive play and is engaged with the actuator's drive.
The electrical connectors can sometimes make intermittent connection.

To improve engine performance further, remove the gauze filters from inside the cam covers. At the suction side you'll find a pinhole, probably blocked with carbon deposits from infrequent oil changes.

Simon