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Discussion Starter · #1 ·
Hi

New to the forum but I'm hoping RRPhil or anyone else equally knowledgeable may be able to offer some advice.

First, I should confess that I actually own BMW not a RangeRover, however they share the same gearbox (ZF 2HP26) and searching for a solution to my problem led me to this excellent forum, so I'm hoping you might take pity and help out. :)

Anyway back to the problem, I have a 2004 BMW 535D with 170k on the clock, I've owned it for just over a year however recently the gearbox behaviour has been getting worse so I'm looking for some advice regarding a possible solution.

Symptoms
Occasionally under load I get a "cattle grid" style rumbling (suspected Torque Convertor)
Gearshifts can occasionally be quite hard and clunky
The main problem is the constantly fluctuating revs. Under any sort of load the revs are constantly surging and it sounds it's changing gear all the time. It also feels akin to when the clutch is slipping on a manual gearbox i.e. the revs seem a lot higher relative to the speed of the car.

I took the car to a transmission place in Nottingham who took it for a spin with me and said it needed completely refurbing at a cost of £2000 +vat.

His diagnosis was that the cattle grid sound was due to the torque convertor failing and that the surging (even when putting it in manual mode and holding it in gear) was due to worn bushings on the input shaft which was allowing fluid to leak past the seal and therefore causing unstable hydraulic pressure. (It sounds similar to this diagnosis http://forums.bimmerforums.com/foru...45i-transmission-slam&p=21919159#post21919159) The difference with mine is that I don't have any error codes being thrown.

Any way I'd welcome any thoughts on any ways to confirm or deny this diagnosis before blindly spending £2400 on anew transmission

cheers

Matt
 

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Hi Matt,

The 6HP26 wasn’t used in Range Rovers until 2006MY (2007MY for diesels) so you BMW chaps have more experience (and mileage) on this transmission than we do. I can’t recall seeing a post on the Range Rover forums describing exactly your problem, though from our experience with the 5-speed units the ‘cattle grid’ noise does sound like a worn out torque converter lock-up clutch. The only recurring issues that seem to be reported on here regarding the 6HP26 relate to faults with the Mechatronic unit solenoids (& the infamous 2-1 rollout shift, of course). I’m not familiar with the issue you mentioned regarding the worn bush and resulting hydraulic leakage so that’s interesting information, but as the shaft only transfers (low pressure) lubrication flow to the intermediate shaft at that bush I don’t see how this could influence any of the clutch pressures.

The surging you’re experiencing could be related to the TC LUC also. It might be worth swapping the LUC solenoid with an identical neighbour and seeing if the problem moves with it?

Easy for me to say (because you’d be paying for removal & refitting of the transmission twice if it’s not the case) but I’d be tempted to fit a re-manufactured torque converter (from JPAT or Sussex Auto Parts) initially and see if the problem sorts itself. There’s no need to open up the transmission to replace the TC so any competent mechanic should be able to perform the swap.

Phil
 

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Discussion Starter · #4 ·
Thanks for the quick reply Phil :)

Yes I've searched quite extensively and not found any threads with what seems to be the exact symptoms I'm experiencing but you're right my next step is to get the Torque convertor done, I was just umming an ahhhing whether to bite the bullet and also do all the seals and fibre clutch packs whilst the box was out, I've seen your excellent guide on the 6hp26 teardown and nothing scared me too much there, the only thing I'd need to do would be fabricate one of those compression tools you made for the pressure clip. Or do yu thnk tha would be a waste of time as none of those things are likely to be contributing to my problem?

I've already spoken with JPAT and Sussex Autos and was surprised with the price difference between some of their parts! Torque Convertor - Sussex Autos (£187.50 +vat) JPAT (£337.98+vat) both on a core exchange basis.

cheers

Matt
 
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