Oil / Fume smell drawn in by your heater / blower which goes away if you stick it on recirculate it could be your breather hose has split...
tools needed
10mm spanner / socket, ratchet and short extension
end cutters or CLIC AND CLIC-R type pliers

and nut runner / screw driver for jublie clips
new breather hose part #71769083 (modified/ improved part)

jublie clips to suit circa 20mm
first open the bonnet and free the air box
to do this
remove the rubber front intake mount by pulling it away
like so:


next with a 10mm socket / spanner remove the 2 mounting bolts:


and take care not to loose the 2 "top hat" spacers from the mountings:

next support the air box and pull up slightly to remove from back mounting:

and pull off smaller breather hose off back of air box (this is just a push fit)


its worth looking at this one too for signs of cracking too
for reference it locates on the bottom of the inlet manifold

These are the type of clips your are now confronted with on the breather hose (i removed mine a while ago so a pic of one on the Radiator bottle will have to suffice to show you what you are up against.....

i just nipped mine with the end cutters till they released
like this

but you can use the correct pliers if you want to re use them (i just used Jublie clips (worm drive hose clamps when i refitted makes it simpler to clean out at a later date and to change the air filter just undo one and whip the lot off)

then pull the hose off each end and replace in reverse order (i found it easier to fit to the air box first then to the rocker box top) when tightening jublie clips dont over tighten on the plastic spigot on the air box as you can break it just nip it up enough to stop the hose from pulling off

DO NOT FORGET to put the small breather back on the air box when re fitting
tools needed
10mm spanner / socket, ratchet and short extension
end cutters or CLIC AND CLIC-R type pliers

and nut runner / screw driver for jublie clips
new breather hose part #71769083 (modified/ improved part)

jublie clips to suit circa 20mm
first open the bonnet and free the air box
to do this
remove the rubber front intake mount by pulling it away
like so:


next with a 10mm socket / spanner remove the 2 mounting bolts:


and take care not to loose the 2 "top hat" spacers from the mountings:

next support the air box and pull up slightly to remove from back mounting:

and pull off smaller breather hose off back of air box (this is just a push fit)


its worth looking at this one too for signs of cracking too
for reference it locates on the bottom of the inlet manifold

These are the type of clips your are now confronted with on the breather hose (i removed mine a while ago so a pic of one on the Radiator bottle will have to suffice to show you what you are up against.....

i just nipped mine with the end cutters till they released
like this

but you can use the correct pliers if you want to re use them (i just used Jublie clips (worm drive hose clamps when i refitted makes it simpler to clean out at a later date and to change the air filter just undo one and whip the lot off)

then pull the hose off each end and replace in reverse order (i found it easier to fit to the air box first then to the rocker box top) when tightening jublie clips dont over tighten on the plastic spigot on the air box as you can break it just nip it up enough to stop the hose from pulling off

DO NOT FORGET to put the small breather back on the air box when re fitting