Hi all,

Just started having issues with the gearbox on my 2008 3.6 TDV8.

It's started to hang on to 4th gear up to about 3k revs before it can be forced to shift up by lifting off the throttle a few times. Also, if I'm in 4th gear and coming to a halt (approaching a junction, for instance) then instead of shifting down through the gears it just seems to go into neutral and the engine is idling even though I'm still slowing down from about 40mph.

I'm also getting some juddering at speed, which started at the same time as the gearbox issue.

I've scanned the car and I'm not getting any codes and there are no lights on the dash.

I've no history for this car, so don't know if the gearbox has ever been serviced. I'm going to assume it hasn't. Would that help matters? The car is on 118,000 miles.

I'm having these issues when the car is both cold and warm.

Any help would be much appreciated.

TrustyBib said:

Hi all,

Just started having issues with the gearbox on my 2008 3.6 TDV8.

It's started to hang on to 4th gear up to about 3k revs before it can be forced to shift down by lifting off the throttle a few times. Also, if I'm in 4th gear and coming to a halt (approaching a junction, for instance) then instead of shifting down through the gears it just seems to go into neutral and the engine is idling even though I'm still slowing down from about 40mph.

I'm also getting some juddering at speed, which started at the same time as the gearbox issue.

I've scanned the car and I'm not getting any codes and there are no lights on the dash.

I've no history for this car, so don't know if the gearbox has ever been serviced. I'm going to assume it hasn't. Would that help matters? The car is on 118,000 miles.

I'm having these issues when the car is both cold and warm.

Any help would be much appreciated.

Click to expand...

One for @Bemble

Try posting on the L322 section of RangeRovers.net. There is a fellow there, RRPhil, who is an expert on those transmissions.

Take a small sample of the gearbox oil, if it's black don't empty it out!! .
If its a clowdy red/blue or clowdy in general it could have been ignored for a while.
If clean then it could have been emptied recently in an attempt to save it.
Shuddering could mean wear inside the box.
With the oil sample pour it into some white paper and check for dust/debris.

Mark Piercy said:

Take a small sample of the gearbox oil, if it's black don't empty it out!! .
If its a clowdy red/blue or clowdy in general it could have been ignored for a while.
If clean then it could have been emptied recently in an attempt to save it.
Shuddering could mean wear inside the box.
With the oil sample pour it into some white paper and check for dust/debris.

Click to expand...

Thanks, I’ll give that a go. What’s the significance of the black oil? Why shouldn’t I empty that out?

Also make sure the filler plug is removable first, before taking samples or draining anything.

pwood999 said:

Also make sure the filler plug is removable first, before taking samples or draining anything.

Click to expand...

A very good point!!

TrustyBib said:

Thanks, I’ll give that a go. What’s the significance of the black oil? Why shouldn’t I empty that out?

Click to expand...

If the oil is black and smells burnt then it could well be the clutch disk material suspended in the oil. If emptied out there is a good risk the clutch disks will just slip!!
Hopefully not the case.

You have the ZF 6HP26X transmission.

“...It's started to hang on to 4th gear up to about 3k revs before it can be forced to shift down by lifting off the throttle a few times...”

I assume you mean shift up rather than shift down? One reason for the transmission to hold on to the lower gears is because the fluid is overheating (cooling strategy mode) but, as your having the issue when the transmission is cold, this seems very unlikely to be the cause.

Wear of the rear stator bush (caused when ZF were experimenting with lead-free materials) is a very common issue with the 6HP26/28. The bush acts as a seal for the E-clutch, which is used in 4th, 5th & 6th gears. The proportion of turbine shaft torque seen by the clutch is 72.6% in 4th, 125.5% in 5th and 100% in 6th. Consequently, 5th gear will be the first to slip as a result of pressure being lost through leakage. The transmission controller will therefore hold the transmission in 4th gear to prevent the clutch pack being damaged through overheating. Eventually the clutch will slip in all three higher gears and the transmission will then not upshift above 3rd gear.

Maybe you’re just starting to see the early signs of this issue? (although it would be more likely to happen when the fluid is hot, as the lower viscosity increases the leakage).

“…if I'm in 4th gear and coming to a halt (approaching a junction, for instance) then instead of shifting down through the gears it just seems to go into neutral and the engine is idling even though I'm still slowing down from about 40mph…”

I don’t know if your diagnostic tool can measure & record live data but it would be interesting to see if the solenoids are actually being triggered for downsequencing. If they are, it could possibly be that the torque converter lock-up clutch isn’t engaging so there’s no overrun braking.

“...I'm also getting some juddering at speed, which started at the same time as the gearbox issue...”

Again, this could possibly be the torque converter lock-up clutch playing up, when it’s in controlled slip mode. Live measurement would also allow this to be investigated, if your diagnostic kit has the capability.

Anyway, certainly worth checking the fluid first.

Phil

P.S. For info. RRPhil & Bemble are the same person

Bemble said:

I assume you mean shift up rather than shift down?

Click to expand...

Apologies, yes. I've edited the original post to reflect.

Bemble said:

I don’t know if your diagnostic tool can measure & record live data but it would be interesting to see if the solenoids are actually being triggered for downsequencing.

Click to expand...

My diagnostic tool can measure live data, but I'm unsure to what degree as it's not a particularly expensive one. I'll give it a go tomorrow and see what I get.

Bemble said:

this could possibly be the torque converter lock-up clutch playing up

Click to expand...

If this was the culprit, what's required to repair? Is it a full gearbox rebuild or are there any less-involved solutions?

Thanks for your help.

The torque converter is separate to the transmission i.e. you don’t need to open up the transmission to replace it, though you do need to drop the transmission out of the car to gain access to it. Any competent mechanic can replace a torque converter. There’s no specialist knowledge of automatic transmissions required.


Note that the Y94 converter features a captive clutch which requires specialist skills & knowledge to accurately re-weld the LUC piston retainer back into the correct position. Companies such as JPAT and Sussex Autos have the necessary equipment and know-how and can re-manufacture a torque converter for a lot less money than a new one.



Phil

I'm having a specialist help me with diagnosis later today, but to be on the safe side I'm preparing to have to remove the transmission.

I've just been going through the manual for removal and reinstallation, and it looks as though I need the following parts:

- 12x driveshaft bolts
- 4x flexplate bolts
- 1x torque converter fluid seal
- Various O-rings

Does anyone have the part numbers for these to hand by any chance?

Anything that I've missed? Any other jobs worth doing in there whilst I have the gearbox out?

Thanks

Hi everyone, just to close this issue off - my torque converter had given up the ghost. Drained the oil and it was completely black and had a very nasty burnt smell to it.

I had it rebuilt at Sussex Autos for £300 inc VAT and they provided an amazing service. Very quick turnaround and also provided a lifetime warranty.

Fitted the new torque converter, cleared the old adaptations, changed the oil and filter/pan (genuine ZF parts) and she's now running sweet. Very responsive with the gear changes and much smoother than before too.