Chapter 1 Routine maintenance and servicing

Every 30 000 miles or three years 1•2324.7 On SEFi fuel injection engines,disconnect the mass air flow sensor wiringmulti-plug . . .24.8 . . . slacken the hose clip anddisconnect the intake hose from the airintake duct . . .24.9 . . . then undo the retaining screws orrelease the clips and lift off the air cleanerlid complete with mass air flow sensorSEFi fuel injection models7 Disconnect the mass air flow sensor wiringmulti-plug (see illustration).8 Slacken the hose clip and disconnect theflexible rubber intake hose from the blackplastic air intake duct (see illustration).9 Undo the retaining screws or release theclips and lift off the air cleaner lid completewith mass air flow sensor (see illustration).All models10 Lift out the element, and wipe out thehousing (see illustrations). Check that noforeign matter is visible, either in the air inletor in the air mass meter, as applicable.11 If carrying out a routine service, theelement must be renewed regardless of itsapparent condition. Note that on models soequipped, the small foam PCV filter in the rearright-hand corner of the air cleaner housingmust be cleaned whenever the air filterelement is renewed (see Section 25).12 If you are checking the element for anyother reason, inspect its lower surface; if it isoily or very dirty, renew the element. If it isonly moderately dusty, it can be re-used afterblowing it clean from the upper to the lowersurface with compressed air.Warning: Wear eye protectionwhen using compressed air!Because it is a pleated-papertype filter, it cannot be washedor re-oiled. If it cannot becleaned satisfactorily with compressed air,discard and renew it.Caution: Never drive the vehicle with theair cleaner filter element removed.Excessive engine wear could result, andbackfiring could even cause a fire underthe bonnet.13 Refitting is the reverse of the removalprocedure. Ensure that the element and coverare securely seated, so that unfiltered aircannot enter the engine.Air cleaner temperature controlsystem check (carburettormodels)14 In order for the engine to operateefficiently, the temperature of the air enteringthe inlet system must be controlled withincertain limits.15 The air cleaner has two sources of air, onedirect from the outside of the enginecompartment, and the other from a shroud onthe exhaust manifold. On HCS engines, awax-controlled thermostatic valve controls aflap inside the air cleaner inlet. When theambient air temperature is below apredetermined level, the flap admits airheated from the exhaust manifold shroud; asthe ambient temperature rises, the flap opensto admit more cool air from the enginecompartment until eventually it is fully open. Asimilar system is used on CVH engines,except that a vacuum actuator modifies anyopening or closing action of the temperaturesensor on the flap valve, according to the levelof the inlet manifold vacuum under runningconditions.HCS engines16 This check must be made when theengine is cold. Detach and remove the aircleaner inlet trunking. Examine the position ofthe check valve within the duct. When theunderbonnet air temperature is below 28ºC,the valve must be open to allow hot air toenter the filter (see illustration).17 Refit the inlet trunking. Start the engineand run it until it reaches its normal operatingtemperature, then stop the engine, removethe inlet trunking and check that the valve hasclosed off the air passage from the exhaustand opened the main (cool) air inlet.18 If the flap does not operate correctly,check that it is not seized. Apart from thisthere is no adjustment possible, and the unitshould be renewed if faulty. Refit the air inlettrunking on completion.CVH engines19 This check must be made when theengine is cold. Disconnect the main air inletduct, and visibly check that the flap to thehot-air inlet is closed (i.e. open to the passageof cold air).20 Start the engine, and check that with the124.16 Air cleaner inlet and flap valve onthe HCS engineA Main air cleaner inlet (cool air)B Warm air duct (flap open)24.10a Removing the air filter element oncarburettor engine models . . .24.10b . . . and on EFi and SEFi fuelinjection engine models1595Ford Fiesta Remake