The manual 2.5 DSE can experience erratic lumpy tick-over due to numerous reasons, most of which are easily diagnosed. My own vehicle suffered from this problem and it took two years of trial and analysis using a Rovacom Lite diagnostic system, to deduce that the problem was caused by a faulty dual mass flywheel. A number of other owners helped me confirm this fault and the classic symptom appears to be that it occurs after the transmission has reached full engine temperature (not just water temperature on gauge), usually after 7-8 miles or more from cold. The symptom is a stutter or uneven tick-over when stopped at a junction. This disappears if the accelerator is very lightly pushed or touched.
Replacing the DMF is an expensive job through Land Rover dealers, with estimates in the region of £1200- £1300 including labour and VAT. The parts I fitted to my own vehicle were manufactured by LUK and on removal of the original ones, were found to be identical to the OEM parts, including the part numbers. The difference in price between 'Genuine Land Rover Parts' and LUK parts was in the order of £350, although they were identical and from the same manufacturer. 'Genuine Land Rover Parts' are NOT made by Land Rover themselves as this exercise demonstrates, so this description is mis-leading and it is better to deal with LUK distributors than with Land Rover! If replacing the DMF, it would be wise to replace the clutch assembly (LUK) at the same time and also the two roll-pins in the clutch actuation fork, located on the shaft inside the clutch housing. A clutch alignment tool is needed during re-assembly. LUK make OEM parts for BMW as well.
The following photographs show the P38 suspended on four ramps, the gearbox to trolley jack adaptor that was made for the job and the gearbox/transmission assembly then mounted on the trolley jack below the vehicle. The P38 was set on maximum height and the battery disconnected before work started. (Switch ignition off and remove battery negative terminal within 30 seconds to disable alarm & immobilizer) The gearboxes/transfer box were removed as a single unit, but there is only just enough space to manhandle the unit - to the millimeter. With hindsight, it might be easier to split the transmission. The flywheel bolts were loctited during reassembly and torqued to the recommended 77 ft.lb.
(1) - P38 on four ramps (2) - Bracket to fit trolley-jack
(3) - New DMF in position (4) - New clutch cover before fitting
(5) - Clutch fork (note copper grease) showing roll-pins (6) - Gearbox/transmission assembly on jack
Testing after completion showed not only a complete absence of the fault, but a noticeable improvement in fuel economy and better torque with the vehicle pulling smoothly from lower revs than previous. (This P38 is also fitted with a digital power upgrade unit from Rimmer Bros., which dramatically increases engine power over the standard 2.5 DSE.) See video of my faulty flywheel on 'youtube' at http://www.youtube.com/watch?v=2OPGJR_9c2s with another P38 example shown at http://www.youtube.com/watch?v=3vENIk8UXQs
Since completing this repair, I have tried investigating the problems with dual mass flywheels (DMF's) and I sent an email to LUK in Germany asking them for a technical explanation as to why their products are failing in the P38 Range Rover. My email was addressed to the Technical Director of LUK and sent to 'firstname.lastname@example.org' - I expected a professional reply but instead I received an attempt to either hide the truth or to 'pass the buck". The question I asked is shown below:.
"As the high number of failures is a known problem for the motor industry, your company must already be aware of these failures. As an engineer, I would like to hear officially from your company, the technical reason for the high number of failures? What actually fails and why?"
The answer I received was:
Dear Mr. Bufton,
thanks a lot for having contacted us concerning your problem with the Dual Mass Flywheel.
Please note that the responsibility for further information lies with Rover so it would be better to contact Rover in this case directly.
We are sorry that we can not help you further.
(Personal identity removed after request from Corporate Counsel Schaeffler Group Automotive)
LuK GmbH & Co. oHG
77815 Bühl / Germany
Tel.: +49 7223 / 941 -623
Fax: +49 7223 / 941 -7923
(Email address removed after request from Corporate Counsel Schaeffler Group Automotive)
In my own opinion, this non-committal reply shows that LUK are well aware of this problem and their reluctance to give an honest, truthful reply does nothing to support the morality or professionalism of their company and possibly of Land Rover. My suggestion to anyone else who is having problems, is to contact LUK in Germany via their web-site or published email address and see if they have any more success in receiving an explanation? If any further information is received concerning this fault it will be published on this page. What is the motor industry trying to hide regarding the use of the DMF in modern diesel engined vehicles and why are they failing? Why can't LUK and Land Rover be honest with their customers regarding items that are faulty by design and why can't they solve the problem?
One observation is that the flywheel position magnets, used by the flywheel position sensor, are located on the front half of the flywheel that is bolted to the crankshaft, so why does a fault between the two flywheel halves cause the lumpy tick-over problem? Is it due to reduction in change in inertia on the engine side? Magnets can be affected by heat and a coating of rust (which they had) could theoretically affect the magnetic permeability of the air gap to the sensor, so are the magnets deteriorating over time along with the flywheel? If anyone has thoughts, ideas, or more information I would be interested to know.
More information on how this problem affects many other makes and models of vehicles can be found at: http://www.honestjohn.co.uk/faq/faq.htm?id=115 .
A technical information and data sheet containing an overview of the LUK Dual Mass Flywheel design can be downloaded from the manufacturers web-site at http://www.schaeffler.com/remotemedien/media/_shared_media/library/downloads/luk_zms_de_en.pdf. The design of these flywheels is an extremely complex procedure and a technical design document by LUK, showing some of the calculations and demonstrating the high level of complexity involved in the design of these flywheels can be downloaded from http://www.schaeffler.com/remotemedien/media/_shared_media/library/downloads/02_the_dual_mass_flywheel~1.pdf. From the details in the last document, it is not surprising that these flywheels are failing as there are so many indiividual components involved in their construction, any one of which could cause problems, but the question that needs answering is why they fail in some makes of vehicle but not in others? Perhaps the future solution is to go automatic as they do not use the DMF?
Since writing the above, an ex-student of mine has experienced the failure of a dual mass flywheel from a different manufacturer, on a Mitsubishi Shogun - cost of the replacement part £1514 + VAT. He could not afford the cost of a new part and the garage welded both halves of the flywheel together and fitted a new clutch. He reports that it drives very much the same as with the original DMF. This drastic action is being caried out in the USA on certain vehicles and also on Ford Transit DMF's by some garages in the U.K.Clearly something must be wrong with the design of these flywheels or the materials used in their construction? Surely the cost of such failures should be reinbursed by motor vehicle manufacturers, if necessary by governmental legislation? (Pigs can fly!)
Further thoughts on this subject - I observed that the Mitsubishi Shogun clutch-plate has a sprung centre, whereas the Range Rover P38 has a clutch plate with no springs. In the case of the P38 flywheel, it might be worth exploring a similar option - welding the faulty DMF and finding an alternative clutch plate fitted with centre springs? If anyone decides to try this option, please report back with the results - favourable or otherwise! Update 02.07.2010: Regrettably the welded DMF on the Shogun failed later on and the owner had to buy a genuine new unit at the cost of around £1500!
Useful information regarding maintenance of the P38 can be had from http://www.rangie.com and a really friendly members' forum with a wealth of knowledge is to be found at http://groups.google.co.uk/group/rangie-com?hl=en-GB . P38 owners regularly post problems and solutions on this forum. If you are an off-road enthusiast then visit Dante's web-site at