Spark Plug Renewal, V6

What Goes In

Firing order is 1-4-2-5-3-6. Cylinder 1 sits at the timing-chain end of the engine. 2.0 and 2.5 take XR8 42795 or NGK TR6AP-13E. 3.0 takes C2S 46895 or the same NGK. Where the plug is adjustable, set the gap to 1.3 mm. Seat them at 15 Nm in the aluminium head. Multi-electrode plugs leave the packet as they are; do not bend the electrodes.

Access

Battery earth lead off first. Lift the coil packs clear of the plugs. The air cleaner assembly has to come off for room over the bank. Work with a deep socket or box spanner on an extension, and keep the socket square on the insulator. Side load cracks the ceramic.

Reading The Old Plugs

• Clean white nose: lean mixture, or a plug that runs too hot.
• Hard black crust: rich mixture.
• Black and oily: worn engine as well as a rich mix.
• Light tan to grey-brown: mixture and engine in fair order.

Gap And Fit

On a single-electrode plug, measure with a feeler or wire gauge. Bend only the outer electrode until the blade is a firm sliding fit. Never bend the centre electrode. Wipe the threads, start each plug by hand (a short rubber hose over the terminal helps you feel a cross-thread before you hurt the head), then torque to 15 Nm. Coils and air cleaner go back on, earth last.