You will spill a little diesel so place some rags or an old sheet of ply under the car. With the air filter in place you can't see the wood for the trees so whip that off! Undo the hose clips at each end of the inlet pipe;
....and the finger clips on the breather pipe;
.....then lift the pipe out of the way;
Unclip the air filter cover and unplug the wires from the air flow meter, remove the filter and now you can get at the bolts in the bottom of the filter casing. Remove the 10mm bolts;
......and now you can see what you are doing with the filter quite nicely. You shouldn't be able to mix up the fuel pipes but if in any doubt just mark one or put a bit of tape on it. Use a pair of pliers to squeeze the clips and slide it down the pipe a little;
Wriggle the pipes to loosten then pull them down off the filter head. Now by squeezing the anchor clips, unplug those "suspect" wiring plugs from the heater;
.....and the water ingress switch;
Now you will have to prize the plugs off the inner wing. One broke on this car shown but there isn't much you can do to avoid it and you might have to use a tie wrap afterwards. You could try softening the plastic by carefully pouring very hot water on it but don't lose any sleep over it! With everything disconnected you can unbolt the housing off the bracket, however, if you don't have a vice just loosten the filter with a filter wrench now while it is still attached;
Lift the assembly off and take it to the bench;
CAREFULLY grip it in the vice and use water pump pliers to pop that water switch off;
It is false economy not to fit a new filter at the same time so using all new seals lightly oiled with clean engine oil or diesel, screw the new filter to the new head and the water switch to the bottom of the filter. It might be an idea to do this with the filter in the upright position to make sure the seals do not get displaced. Assemble the parts loosely first making sure the seals don't twist then carefully grip the head in the vice and nip them all up. They only need to be hand tight - don't get carried away! On my photos it is just a filter change so the old head is refitted. Take the assembly back to the car and refit it. Connect both plugs, slide the pipes back on and reposition the clips. Now with everything back on you will need to prime the air out of the system. Simply pump that black plunger on the head until it becomes quite stiff;
Now that is done you can refit the air filter and hose and don't forget that plug on the airflow meter. When you start the engine for the first time it might cough a little bit as the last remnants of air are purged but don't worry about that.
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