Td5 D2 engine - Fuel Leak

Always on the lookout for the next maintenance issue to emerge whilst at the same time keeping an eye on any existing 'conditions'. 

The other day after a drive to the local superstore, there was a distinct smell of diesel fuel in the air when I got out. It could have been any of the cars around although I recall there not being that many parked in the immediate vicinity. I planned to have a closer look and investigate more after returning after the shopping. 

Needless to say it slipped my mind and with the shopping all stored away and no hint of diesel fumes, I happily continued the journey. 

On returning home after a little drive around I was greeted on exiting the door by the smell of Diesel again. This obviously meant the fumes where from Hx and that "pit of the stomach' feeling returned. 

Reverse parking Hx on the drive further revealed a trail of drips on the road surface marking out the manouvere kind of like a blood trail.

I quickly placed a finger into a fresh splash and it felt and smelt of Diesel. This was serious,  I have never seen so much obvious spillage before! Reluctant to get under and check things out I elected to wait till the morning and mulled the situation overnight.

Initial fear was the FPR was leaking again. I had repaired this back in May 2013 and it was quite an undertaking to get at it...  I recalled fitting a 'leak off tube' onto the regulator casing (using some spare blue vac.tube) and routing this tube down below the chassis. My thinking  being that any future leaks would be easier to detect and help to keep the rest of the engine clean!

The next morning I went out to investigate the leak. There were no telltale puddles under Hx or under the bonnet. I removed the acoustic cover from the engine to get visual access to the regulator. It looked dry enough and I was able to get fingers down there and check all the hoses and connections which all appeared to be dry and with no residue of a diesel leak anywhere in the engine bay, things started to get a bit non predictable.

The fuel system on the Td5 has a working pressure of 4 bar which is the equivalent of 58 psi and more then enough to turn a pin-prick hole into a gushing fountain. I figured that any leak would have left a tell tale stain even after the diesel had slowly evaporated and looking for fresh stains should be a guide to the leaks location.

I decided to start the engine up and observe the fuel system with the engine running at full pressure. It started with its usual eagerness and I revved it up above the idle for a while. There was nothing obviously leaking under the bonnet and the 'drip-tube' was dry. I then switched off and scratched my head with a cup of tea.

When I looked out the window waiting for the kettle I immediately saw a big dark patch on the floor behind the rear offside tyre. It was like the water run-off puddle when the icy frost melts, but I knew today it was something else. 

Took this photo after I had mopped all the spilt diesel up! This was after running the engine for a minute or two. I did not see this spillage form as I was concentrating on the engine bay. (DOH) It would have been constructive to see if the spill occurred with the ignition on and the pump 'priming' and/or with the engine running or even when the engine stopped ..

Either way, it's clear the leak is from the area of the fuel filter..

Two views of the fitted fuel filter mounted on the chassis rail inside the rear wheel arch. 

This filter is overdue for replacement and I have a 'Mahle KC80' waiting to be fitted for over 12 months while I was supposed to be sorting the ongoing 'water sensor' issue.

The fitted position of the fuel filter on the Td5 Discovery has always seemed odd to me. Admittedly it is easily accessible for maintenance, but being exposed and close to the rear wheel and open to the elements and flying debris kicked up from the tyre could be an issue. Particularly with that water sensor and it's electrical plug hanging low on its base..

Even the Td5 Defender has a similar issue with its location, but it is fitted with a metal cover plate to protect the filter from the elements.

Here is the filter and cover installed on a Defender, more about this later....

FINDING THE SOURCE  OF THE LEAK

Whatever the cause of this leak is, Hx is going nowhere till its sorted.

Two more views showing the fitted filter. The top of the filter where all the pipes attach appears dry so I believe the leak is from the filter body or the water sensor/drain plug at the bottom. If the above photos are enlarged it is possible to see drips of diesel on the lowest surfaces and even on the end of the sensor drain tube.

The filter body is secure but the water sensor appeared to tighten up a bit. Only noticed this when I tried removing the sensor and found I was turning it the wrong way!

Historically, there is a well documented fault with the fuel filter supply pipes that can result in one of the pipes chaffing on other components and leaking. This fault was even the subject of a VOSA recall program that effected thousands of Discovery 2.  Hx is unfortunately one of them but I have no idea if the remedial work was ever done to Hx. It just involved re-routing the pipework to avoid any possibility of chaffing. It is possible that it is the cause of the leak but surely if so then there would be more direct evidence of the source of the leak? 

For now, all my money is on the drain plug/ water sensor at the base of the filter. There is a lot of documented problems with these units ranging from snapped wires, false alerts (Hx has those! ), cracked and leaky bodies..  So much hassle in fact that Land Rover even deleted them from the final production run. However, knowing the cost of these units the reason for deletion was more likely penny-pinching cost savings.

What I propose to do is to fit the new filter complete with the supplied standard white plastic drain plug and delete the fitted water sensor and drain that is currently fitted on Hx.

This is a photo of the Td5 Discovery water sensor/drain (WKW500070). It can be seen fitted to the base of the fuel filter in the above photos and also shows where the electrical cabling attaches. The tubular drain is also clearly visible here.

This is the water sensor and wiring loom from a Td5 Defender (WKW500060 ). Although the sensor body and mounting is the same, the electrical plug is different and they are not interchangeable. The Defender installation offers a better level of protection from the elements inside the wheel arch then the exposed Discovery install. 

This is the new fuel filter. It came fitted with the white plastic drain plug that is interchangeable with the 'water sensor' on the Td5. 

The Land Rover part number ESR4686 is for all Td5 engines and it is readily available from a number of aftermarket suppliers. I bought this filter back in June 2015 for £8.40 and only now am I getting around to fitting it!

I don't know who the OEM factory-fitted filter was made by. And I have to assume that the leaking filter has never been changed before. 

I sourced the new filter from a LR specialist garage that stated they used Mahle filters for all their workshop services.

Interesting to note that this Mahle filter is labelled 'Bearmach' on the box.

Two close ups of the manual drain plug on the base of the filter. The grey rubber washer provides the effective seal and it's recommended that it is lubricated with oil or diesel before fitting. The plastic thread on the drain plug can easily be damaged by excessive tightening so be careful when fitting.

If this drain plug fails in service then all the fuel will drain out and the engine will be starved of fuel. Thinking about it, this is a handy way to sabotage a Td5,  just reach inside the wheel arch and loosen that plug....

I intend to fabricate some kind of a plug to place into the bottom of the drain tube to combat the ingress of dirt given the exposed position of the fuel filter on the Discovery.

REMOVING, REPLACING , PURGING

Removing the old filter is straight forward. It simply screws off just like a standard oil filter. 

It's important to ensure the upper sealing rubber rings are retrieved as they often stay attached to the filter head. 

The new sealing rings should also be lubricated lightly. In service the filter body can get quite warm due to the heated fuel passing through returning from the engine. This may well be a reason for the filters location exposed to the airflow to allow for heat dissipation. The heat and pressure probably contributes in time to the bonding of the rubber sealing ring. 

Another tip is to drain the old filter first and use that fuel or better again, use fresh fuel to fill up the new filter before fitting it in order to help with the 'purging' process. 

I tried to drain the old filter while it was still mounted on Hx by using the water-sensor drain on its base.  At this point it appeared that the water-sensor body was a bit 'loose' and this may well have been the source of the leak. 

Frustratingly, no fuel ran out of the drain hole but instead it flowed out from the top of the sensor body as I loosened it off. I quickly tightened it up to stop the flow then removed the complete filter body and then removed the water sensor and drained the fuel into a suitable container. Quite a bit came out and there was the inevitable spills as well.. It is recommended to wear rubber gloves and old clothes and have some rags handy to mop the spills up.

Above is a generic graphic of the filtration flow through a cartridge type filter. The fuel to be filtered enters around the outer holes in the top panel and exits via the central hole. Any fuel poured into the new filter to prime it should really be poured into the outer ring of holes on the top panel of the filter. 

The Td5 fuel system operates at high pressure and any air in the system must be purged to achieve this. Changing the filter will inevitably introduce air to the system, but the 'purging' process once started is done automatically.

Once the new fuel filter is mounted it is time to start the purge process by turning the ignition key to P2. 

The dash board lights will be lit, but, and this is important... DO NOT ATTEMPT TO START THE ENGINE AT THIS STAGE.

The 'engine management' warning light may well stay illuminated indicating the system has detected a fault (ie..air/low pressure ) in the fuel line. 

Rave and personal experience indicates that at this point the purging starts automatically and will continue for 3 minutes. It is normal for the fuel pump to run for three minutes when the ignition is at P2.

The fuel pump will be heard to surge fuel around the system to remove the air. There is a purge valve built into the filter head and the fuel pump itself. 

Bear in mind that if the new filter is empty, it will need to be filled by the pump and that will prolong the purge process. Three minutes is the 'time-out' period for the fuel pump operation governed by the engine Ecu. If a hand is placed on the fuel lines the pulsing action of the pump can be easily felt, but more noticeably the gurgling and rumbling from the pump in the fuel tank will easily be heard. It may be necessary to repeat the process a number of times to ensure that the air is fully purged from the fuel lines. 

This is a good reason to fill the new filter up with fuel before mounting it. The downside of repeated 'purging' is it can easily drain a weak battery leaving the engine difficult to start. 

Once the purging process is complete, the engine should start immediately or after very little cranking. This is assuming the battery is fully charged and there are no fuel leaks. If the engine fails to start then repeat the purge process.

I followed this sequence when replacing the new filter having filled it with some clean fuel. (pouring the fuel into the outside holes and avoiding the central hole.)

After switching the ignition on, I quickly listened for any noises from the pump area and could hear the surging and a good deal of 'gargling'. This quickly settled down after about 20 seconds and the noise from the pump was imperceptible. I was careful to let the process run for 3 minutes. I then switched the ignition off and checked for any leaking fuel of which there was none. At this point I could have tried starting the engine but I choose to repeat the process again giving another three minutes of purging.

I then attempted to start the engine and it happily fired first turn and ran as smooth as usual.

There is another method of 'purging' slightly differrent to the above 'Rave' procedure.

Basically when at P2 on the ignition, quickly fully depress the throttle pedal 4 or 5 times and the engine mgmt lamp on the dashboard will start to flash. The engine ECU is now in a kind of 'auto-purge' mode and will run the pump for 30 seconds then stop for a few seconds then start the pump again and so on until it declares itself 'purged' and the lamp extinguishes. The engine can now be started as normal.

MORE PHOTOS OF LEAKY FILTERS.

This image from the Web shows diesel leaking from one of the 4 Pipe connections on the top of the fuel filter mounting. The pipes have screw connectors and use copper washers which appear to have failed here. 

The same filter again showing the location of the install in the o/s rear wheel arch. To the right can be seen the rear suspension air-bag and the brake-lines for the nearby wheel. 

This image shows the exposed water sensor on the bottom of the fuel filter. All the dirt and built-up crud is a direct result of its exposed location inside the wheel arch.

This leak was cured by replacing the whole filter head (north of £80).

Same problem again, but this time...

..the intrepid poster (Handy Howie) used some PTFE tape on the effected pipe thread.

Job done !!  And a hefty saving on the cost of a new filter head.

AUTOPSY FOR THE HX FILTER.

This is the fuel filter removed from Hx. The metal label was facing the chassis member. There are no other identifying marks or Brand labels and overall, the surface area can only be said to be 'weathered'.

The base of the filter case has nut flats or 'castellations' formed onto it but they are hardly visible now.

I have owned Hx for 5 years now and never got around to changing the fuel filter till now. Throughout my ownership the dashboard 'water in fuel' light would occasionally briefly light up for just a second or so and then extinguish itself. I figured it to be an electrical glitch as the dashboard light should stay on pernemently till the issue is resolved by draining the water out from the bottom of the filter. 

I had tried to drain the system previously but was dismayed that no fluid at all came out of the drain hole..  Only now with the unit removed from Hx can I see why that was....

Two views above show the inside of the water sensor covered in crud and dirt. The drain hole tube (the bump in the outer ring) can be seen to be completely blocked.

That brass cross-headed screw is part of the electrical sensor and sits inside the filter base surrounded by Diesel fuel.

Three photos above show the now cleaned up water sensor with the cleared out drain tube.

The sealing washer shown below has been fitted in place above.

This is the base of the filter. The sealing rubber washer looks fine but everywhere else is weathered and just shows how dirt, dust and water can find its way into the sensor body as a result of the filters exposed location. 

I have not re-fitted the water sensor onto the new filter preferring to use the supplied white plastic drain. This means that any future water draining needs to be scheduled 'manually' as the warning light system is now disconnected.

  

I also intend to fabricate a plug for the water drain outlet. I secured the now redundant electrical lead and cabling using a cable-tie and stuffed a blob of blue-tack onto the connector terminals to hopefully weather-proof it. 

This is the top panel of the removed filter. The outer sealing ring was also in good condition, as was the central seal, but it is not shown here. The dark patches by the punched holes are all that remains of the dark slimy coating that covered the whole top panel.

Just how long was this filter in service. ?

I have a receipt for a service dated September 2009 indicating a fuel filter change with the mileage on 63094 which matches the MOT dated 8/9/09.  The mileage today is 96248 which gives 33154 miles since last change.

Wonder what the service interval is...?

PROTECTING THE FILTER BODY.

Two views above show the fuel filter installation on a Td5 Defender. It is mounted in the rear wheel arch forward of the wheel...

It consists of two pieces. The mounting plate WKT100010 is shown on the right above and attaches to the chassis via the filter-head mountings and the cover plate.  WKT100020 shown on the left encloses the filter and clips onto the mount-plate. 

These are not expensive items and are still available new...

It is possible to fit this protection (with a bit of modification) to the Td5 Discovery as the above photo shows...

Deleting the water sensor and using the standard white plug would further aid the fitting and the security of the fitment.