MODERN WORKSHOP

1

The induction pipe between the throttle body and air filter housing is in the way of the offside bank of spark plugs, so undo a couple of 8mm bolts that secure the pipe to the throttle body

2

Slacken the large Jubilee clip wrapped around the end of the induction pipe attached to the air filter housing, disconnect a short breather pipe, then lift this long pipe away from the engine bay

3

Each bank of spark plugs is hidden by a cover that helps to protect them and their coil packs. Undo the six 7mm bolts that secure each cover. Be careful not to drop them when extracting these small bolts

4

Space can be tight for accessing and undoing some of the 7mm bolts that secure each spark plug cover in position. Spanners and short ¼in sockets can help to get into some of these tight spots

5 6

Once all of the bolts for each cover have been extracted, lift the covers off. Check their condition – the mounting holes can easily break, but a second-hand cover only costs around £15 Each spark plug has its own coil pack, which needs removing. First, carefully detach the plastic wiring plug for each coil pack by pressing down on a small release tab and levering the connector off

7 8

You may wish to tackle one coil pack and spark plug at a time, so after detaching the plug connector in the last step, undo and extract the two 7mm bolts that secure the coil pack in position Carefully lift out the coil pack. It will offer some resistance at first because it’s attached to the top of the spark plug. Once released, pull it all the way out, but avoid catching the wiring nearby

9

Shine a torch down the spark plug hole to check inside. You may find some coolant or oil inside, which we’ll discuss in step 17. You will need a 16mm spark plug socket to extract this spark plug

10

Use an extension bar and a ratchet to undo the spark plug. The old spark plug shouldn’t need too much force to undo, but if it feels stiff, try spraying some penetrating fluid inside

11 12

Once the spark plug has been fully undone, it should remain attached to the spark plug socket if there’s a rubber grommet inside it. If not, extract it using the coil pack or a rubber hose with an 8mm internal diameter Check the old spark plug is the same as the new ones you intend to fit, ensuring the thread is the same and also the dimensions. The spark plugs may not be the same make because different ones are recommended

13

Use a length of rubber hose (8mm internal diameter) to feed and thread the new spark plug into position. Using the spark plug socket risks leaving its rubber grommet on the spark plug after fitting it

14

The spark plug needs to be correctly tightened using a torque wrench, but first extract the rubber grommet inside the spark plug socket so that it doesn’t remain attached to the spark plug

15 16

Set a torque wrench to 25-29Nm, then tighten the new spark plug. This should be enough to crush its washer and ensure a leak-free seal. These spark plugs must not be overtightened when fitting them Refit the coil pack for the newly fitted spark plug and hand-tighten the two 7mm mounting bolts with a small ¼in ratchet or short spanner. Reconnect the wiring, then move on to the next one

17

Typical problems that may arise when changing spark plugs include oil and coolant contamination. Oil can leak past the camshaft cover gasket. Coolant can drip down after topping up the expansion tank

18

When you’ve finished one bank of spark plugs and have refitted all the coil packs and reconnected the wiring to them, carefully refit the cover, ensuring the wiring doesn’t get trapped

19

Before refitting the induction pipe that was removed in Steps 1 and 2, check the air filter. Detach an electrical plug on the lid of the air filter housing then release five metal spring clips that secure the lid

20

Open the lid of the air filter housing and extract the air filter. It should be replaced every 12 months or 10,000 miles. If you think it can be reused, check between the pleats on the underside for debris

21

Use paper towel or a cloth to clean inside the air filter housing and remove traces of dirt that could contaminate the air filter. A damp cloth or a vacuum cleaner may help to pick up the dirt

22

Fit the new air filter or refit the old one, making sure it sits inside the housing, allowing the lid to be fully refitted. This can be a little awkward, so take your time manoeuvring the air filter into position

23 24

Spray a little light grease or WD40 inside the ends of the induction pipe that was removed in Steps 1 and 2. This will help make it easier to refit them onto the throttle body and air filter housing Refit the induction pipe, tightening the Jubilee clip at the air filter, refitting the two 8mm bolts at the throttle body and reattaching the electrical plug and breather pipe. Start the engine to ensure it runs