1A.12
Every 20 000 miles - petrol models
18.7 Lift up the cover and remove the filter element (18-va!ve engines) 9 Fit a new air (liter element In position, ensuring that the edges are securely seated 10 Refit the air cloaner cover, engage the rear retainers and secure with the three bolts.
19 Spark plug renewal
1 The correct functioning of the spark plugs is vital for the correct running and efficiency of the engine. It is essential that the plugs fitted are appropnate for the engine (a suitable type is specified at the beginning of this Chapter. If this type is used and the engine Is In good condition, the spark plugs should not need attention between scheduled replacement intervals Spark plug cleaning Is rarely necessary, and should not be attempted
19.2a Disconnecting tho HT leads from Iho spark plugs on 8-valve engines ...
19.4 Removing the spark plugs
unless specialised equipment Is available, as damage can easily be caused to the firing ends. 2 To remove the plugs first remove the air cleaner assembly (8-vaive engines) or the a»r cleaner, resonator and inlet air duct (16-valve engines) with reference to Chapter 4A or 4B. if the marks on the original-equipment spark plug (HT) leads cannot be seen, mark the leads 1 to 4, to correspond to the cylinder the lead serves (No 1 cylinder is at the timing belt end of the engine). Pull the leads from the plugs by gripping the end fitting, not the lead, otherwise the lead conneciion may be Iractured (see illustrations) 3 It is advisable to remove the dirt from the spark plug recesses using a clean brush, vacuum cleaner or compressed air before removing the plugs, to prevent dirt dropping into the cylinders. 4 Unscrew the plugs using a spark plug spanner, suitable box spanner or a deep socket and extension bar (see illustration). Keep the socket aligned with the spark plug • If it is forcibly moved to one side, the ceramic insulator may be broken off. As each plug is removed examine 4 as fallows. 5 Examination of the spark plugs will give a good Indication of the condition of the engine. If the Insulator nose of the spark plug Is clean and white, with no deposits, this is Indicative of a weak mixture or too hot a plug (a hot plug transfers heal away from the electrode slowly, a cold plug transfers heat away quickly). 6 If the tip and insulator nose are covered with hard black-looking deposits, this
19.2b ... and on 16-valve engines
19.9 Ad|ustlng a spark plug electrode gap
indicates that the mixture Is too rich. If the plug is black and oily, then It is likely that the engine is fairly worn, as well as the mixture being too rich. 7 If the Insulator nose is covered with light tan to greyish-brown deposits, then the mixture Is correct and it is likely that (he engine Is in good condition. 6 The spark plug electrode gap is of considerable importance as, if it Is too large or too small, the size of the spark and its efficiency will be seriously impaired. The gap should be set to the value given in the Specifications at the beginning of this Chapter. 9 To set the gap. measure it with a feeler blade and then bend open, or closed, the outer plug elect/ode until the correct gap l9 achieved. The centre electrode should never be bent, as this may crack the insulator and cause plug I allure, if nothing worse. If using feeler blades, the gap is correct when the appropriate-size blade is a firm sliding fit (see illustration). 10 Special spark plug electrode gap adjusting tools are available from most motor accessory shops, or from some spark plug manufacturers, 11 Before fitting the spark plugs, check that the threaded connector sleeves are tight, and that the plug exterior surfaces and threads are clean (see Haynes Hint). 12 Remove the rubber hose (If used), and tighten the plug to the specified torque using the spark plug socket and a torque wrench, Refit the remaining spark plugs In the same manner. 13 Connect the HT leads In their correct order, and refit any components removed for access.
It is very often difficult to insert spark plugs into their holes without cross-threading them. To, avoid this possibility, fit a short length of Si 16 Inch Internal diameter rubber hose over the end of the spark plug. The flexible hose acts as a universal Joint to help align the plug with the plug hole. Should the plug beginto cross-thread, the hose will slip on the spark plug, preventing thread damage to the cylinder head
