As promised, here is a definitive, photo guide to changing the fuel filter on all post 2002 diesel A2s:
Firstly, familiarise yourself with the following parts, as shown in the workshop manual drawing:
You will be changing items 2, 4 and 5 and they are all included in the box when you buy the filter from a dealer. The box contents are shown below:
You will need the following:
Ramps, axel stands and jacks,
10mm socket
27mm socket (hex, not bi-hex)
Gloves to avoid getting diesel all over your hands
Drip tray
Hose Clamps
Proceed as follows:
Raise the rear of the car in whatever way you prefer (I reversed up onto ramps) and then remove the dimpled aluminium cover just in front of the rear nearside wheel (held on by 10mm speed nuts, which often shear off!).
Clean off the filter housing and surrounding areas to avoid contaminating the new filter.
Use the hose clamps to isolate pipes 11 and 12, as shown below:
You can clearly see the front clamp and the rear one is just poking out from behind. This step is essential to avoid loss of prime and airlocks in the system and also to minimise fuel loss. If you don't have clamps, get some otherwise if you proceed beyond this point without, you'll be in a world of pain later!
Anyway, once you have isolated the filter, undo the central 10mm nut and get the drip tray ready - diesel will start to trickle out, but if you lose more than a cupful, something is wrong! You can see the stream of blue diesel coming from the filter in the above photo.
When the trickle has stopped, undo the main cover of the filter housing, using a 27mm socket. Do not use adjustable spanners, mole grips, 12-point (or bi-hex) sockets or anything else. You MUST use a 27mm hex socket, as the nut is plastic and easily deformed unless pressure is applied evenly all around to all surfaces. If you ruin the nut, you will have to buy an entire new housing, as it isn't available separately and it costs £55!
Once you have removed the filter, it is time to change the 3 O rings and insert the new filter:
Cover the new O rings in fresh diesel before tightening them in place. Also, remove any sludge from the cover cap (the bit with the 27mm nut moulded into it), as otherwise the holes in it will be blocked.
Reinstall the filter, making sure you positively get it snapped into position, then screw in the cover cap, to 25Nm and finally the 10mm nut assembly, to 2Nm.
Wipe everything down again, remove the clamps and check for leaks. Leave the car for 30 minutes or so to allow the housing to refill with fuel before driving (nice time to get a cup of tea!), refit the dimpled aluminium plate and lower the car.
Job done!
Cheers,
Mike
