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2006-2009 Range Rover MkIII / L322
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4 Posts
Discussion Starter #1
Hi,

I'm hoping to get some advice. I have newly bought a 2006 Range Rover, 4.4L Jaguar V8, with the 6 speed automatic (ZF6HP26?). 62k miles. Later engine and gearbox but pre-facelift dashboard, manual handbrake, etc. My first Land Rover product, I was really impressed by it...


I've done almost 1000miles since I got the car and it has become more apparent this week that the gearbox is 'slipping' in D.



  • Gear selection seems to work fine - R, N, D, P all seem ok, no noises or thumps or pauses or anything switching in between.
  • There is a hint of the 'cattle grid' noise as it slips.
  • Slipping most obvious on part / little throttle, around 2000-3000rpm. Often acts more like CVT in this range, unless I use more throttle.
  • Slight evidence of rpm 'feathering' on the rpm dial at a steady 30-40mph. You can sort of feel it too.
  • Seems better in Sport mode.
  • Seems better / no slip in manual mode.
  • Occasionally when coming to a stop there is a slight shunt felt, not always, no noise.
  • I have iCarSoft latest v2 reader - shows no gearbox codes when plugged in. No warnings on dashboard etc.


I have car booked in on Tuesday at local garage. Plan is to: -


  • Check gearbox oil level. I do not think it has ever been changed (I see no paperwork to say it has). Inspect for signs of coolant?
  • Drop the gearbox pan and inspect magnets. Assuming no alarming chunks of metal, box will get new pan / gasket / filter.
  • Install refurbished torque converter from Sussex Autos. Refill transmission with new oil.


I am thinking it could be the torque converter with the cattle grid noise, hence the above. I have not seen much evidence of this on the later Jaguar engined cars, compared with BMW where it seems to occur at much higher mileage?

I'm trying to be sensible with what could be wrong, whilst not throwing needless money at it. A few other items floating around my head at the minute are: -


  • Gearbox oil cooler - are these a problem on the Jaguar engine cars like with the earlier BMW ones?
  • Mechatronic unit - is there any way to know if this could be the issue?

Can anyone more knowledgeable please offer any advice?

Not a great start to RR ownership :-?

Thanks
 

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LEGACY VENDOR
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2,369 Posts
It does sound a lot like your torque converter lock-up clutch. The only way to know for sure (without dropping the transmission and replacing the converter) is to monitor the engine, turbine and output speeds together with the EDS 6 signal (TC LUC solenoid current) to see what it’s doing. Clearly, you’d need diagnostics kit which is capable of recording this data at a reasonable capture rate e.g. IIDTool or Faultmate



Phil
 

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Registered
2006-2009 Range Rover MkIII / L322
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4 Posts
Discussion Starter #3
Hi Phil,

Thanks for your response, your posts are the reason I joined this forum. Very informative.

I went out today with the iCarsoft plugged in and it does appear to be happening in the 'range' of the LUC. I have not worked out how to graph the data, but assuming I was monitoring the correct solenoid - 'Pressure control solenoid 6 driver', then the solenoid does appear to be showing 0.05A at idle, which I believe is correct. During driving I saw 0.39A - 0.58A. Do these values seem sensible?

I'm a bit concerned that the LUC could be worn with only 62k miles on the car? Would it be possible that the solenoid 6 is faulty, even if it was showing the correct amp values? I guess a faulty solenoid for the LUC could cause the LUC not to apply enough pressure, even if it was showing the correct amps through diagnostics? Could the LUC get this worn if the car was driven hard around town a lot?

I checked the gearbox temperature after a run - showed 92degC.

One final thing I notice, when cruising at 60mph+ steady speed and the throttle is pressed to accelerate but not enough to kickdown, the rpm raise approx 100rpm before 'take up'. Is that normal? No noises or anything - you would even notice unless looking at rpm.

Thanks again,
 

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LEGACY VENDOR
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2,369 Posts
Would it be possible that the solenoid 6 is faulty, even if it was showing the correct amp values? I guess a faulty solenoid for the LUC could cause the LUC not to apply enough pressure, even if it was showing the correct amps through diagnostics?
Yes, exactly. The solenoid current tells you what it’s being asked to do but doesn’t tell you if it’s doing it. The speed traces show what the lock-up clutch is actually doing. 62k miles does sound like a low mileage for wear in the lock-up clutch, and certainly the 6HP26 is infamous for its solenoid problems. The solenoid currents that you mentioned look about right.

I’d be very interested to learn if iCarsoft can capture and record live data (though I suspect it can’t) and, if so, at what frequency.

I guess that you could speculatively replace just the LUC solenoid (a new one costs £70) but you may be wasting your money. Another possibility would be to remove your Mechatronic unit and send it to Pete Stirrup for testing www.valvebodyuk.co.uk

Phil
 

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2006-2009 Range Rover MkIII / L322
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Discussion Starter #5
I just wanted to leave an update. As mentioned above I bought an OEM service kit for the gearbox - sump / filter / gasket, and new oil (Ravenol ATF 6HP). Step 1 was to drop the sump and check the contents. The oil was dark in colour but the magnets in the sump were clean. The amount of oil suggested the amount in the gearbox could not have been far off so I do not think it was the oil level.

The garage made the decision to install the new service kit and refill with oil (at correct operating temperature) and see if that had any impact after a week or so. This has made a huge difference alone to the gearbox and it seems a lot more positive and the symptoms seem 95% gone. There appears to be no slip now on any of the hills I had the problem before, and no noise. It seems to be getting better each day.

Whether this is short term fix I will have to see. Obviously I have only replaced around half the oil in the gearbox as it was not flushed. If the car behaves I will wait until next MOT (or garage visit...) and have them change the oil again, so should be 75% new oil then.


If the box requires removal and sent away, can anyone recommend places in the UK for these 6 speed ZF gearboxes?


The iCarsoft V2 does indeed capture and record live data. It does this to a removable memory card that comes with it. The frequency I am not sure - I was hoping to remove the card and see what the graphs looked like if the data is readable in Excel or Google Sheets. I would recommend this tool for what it can do for the money. User friendly too.
 
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