Servicing a ‘sealed for life’ automatic gearbox

Various standards and levels of servicing are available for automatic gearboxes – Our Range Rover Sport receives a bespoke treatment from Tektronic

OUR SIX-SPEED Range Rover Sport is about to have its automatic gearbox internally cleaned and refilled with fresh fluid by Tektronic, the transmission and 4x4 specialists in Stirling. An advanced Brainbee 8200 gearbox cleaning and filling machine is being used to completely clean the internal components of the gearbox, thoroughly flush out the cleansing treatment and old oil, and finally refill the system with the correct amount and specification of new automatic transmission fluid.

A particular advantage of the Brainbee is its ability to ensure no crosscontamination of old and new fluids as they are being exchanged, ensuring the final fluid fill is wholly to the required specification. To achieve this, the machine has two pumps, so that while removing old fluid or cleaning treatment it is also introducing new fluid through a separate line, and continually measuring the flow rate and quantities. Removed fluid is discharged into a separate tank for disposal, while a second tank is used solely for new fluid. The measurement of fluid flow rates and volumes during the exchange ensures a continual safe working level of fluid in the gearbox, allowing it to be driven during the process to achieve complete circulation, whilst avoiding any risk of partial seizure.

Service requirements

The Land Rover service schedule states automatic transmission fluid should be renewed every 150,000 miles or ten years, whichever comes first (though the workshop manual states the fluid is ‘fill for life’). In my case, the Range Rover Sport is 12 years old with 127,000 miles covered, and the gearbox still works fine. But I want to keep it that way, so the oil change and flush is timely.

The standard service procedure is simply a draining and refilling of the fluid by removing the drain plug from the fluid pan (sump) under the gearbox and, after complete drainage, replacing the fluid via the level plug hole. The gearbox’s standard oil filter is integral with the fluid pan and is normally only renewed if the fluid is known to be contaminated or work

has been done inside the gearbox.

Fluid deterioration and accumulation of debris within the fluid are known to cause juddering during gear changes. The symptoms usually occur after around 140,000 miles and often the more advanced service shown here can return the auto box to normal smooth service before serious damage is caused. In reality, it’s better to play safe and have the system serviced before the symptoms develop.

Transfusion service

Simply draining and refilling the autobox via the drain and level plugs does not achieve a full removal of the old fluid, and the old fluid filter will still be in place. The filter is an integral part of the fluid pan and, due to the position of the filter’s vertical internal pipe, the fluid pan cannot be removed without raising the engine and transmission, which involves disconnecting the right engine mounting (plus cats and heat shield on petrol V8s). This is because a chassis crossmember (which locates the rear of the front suspension) prevents the fluid pan being lowered. A transmission crossmember at the rear of the fluid pan also restricts access to the screws holding the pan to the gearbox, but access can be improved by releasing the transfer box mounting here to raise the assembly slightly. Incidentally, this transmission crossmember can be unbolted and removed from the chassis, though that is not necessary for this job.

During the service, the Brainbee cleansing and filling equipment will be connected with the vehicle’s gearbox fluid system, allowing the engine (and thus the gearbox components) to be run during the process. By working the gearbox during the treatment, its fluid system will be thoroughly cleaned, including the surfaces of gears, fluid channels, valves and clutch packs. Although this gearbox clean and refill is being performed on a 2006 Range Rover Sport with the ZF six-speed gearbox, the work is applicable to all wet clutch automatic transmissions on other Land Rover models.

Filter conversion

The gearbox’s internal fluid filter will also be changed, along with the fluid, and in the case of this vehicle we’ll be accomplishing this by fitting a filter conversion kit. This allows the filter to be replaced without lifting the engine, and will make the job easier in the future. This filter conversion applies only to the ZF6HP gearboxes in Range Rover Sport 2005 to 2013, Discovery 3 and 4, and Range Rover L322.