Chapter 1 Routine maintenance and servicing

Braking system 9•11Bleeding - using a pressurebleedingkit24 These kits are usually operated by thereservoir of pressurised air contained in thespare tyre. However, note that it will probablybe necessary to reduce the pressure to alower level than normal; refer to theinstructions supplied with the kit.25 By connecting a pressurised, fluid-filledcontainer to the master cylinder reservoir,bleeding can be carried out simply by openingeach screw in turn (in the specified sequence),and allowing the fluid to flow out until no moreair bubbles can be seen in the expelled fluid.26 This method has the advantage that thelarge reservoir of fluid provides an additionalsafeguard against air being drawn into thesystem during bleeding.27 Pressure-bleeding is particularly effectivewhen bleeding “difficult” systems, or whenbleeding the complete system at the time ofroutine fluid renewal.All methods28 When bleeding is complete, and firmpedal feel is restored, wash off any spilt fluid,tighten the bleed screws securely, and refittheir dust caps.29 Check the hydraulic fluid level in themaster cylinder reservoir, and top-up ifnecessary.30 Discard any hydraulic fluid that has beenbled from the system; it will not be fit for reuse.31 Check the feel of the brake pedal. If itfeels at all spongy, air must still be present inthe system, and further bleeding is required.Failure to bleed satisfactorily after areasonable repetition of the bleedingprocedure may be due to worn mastercylinder seals.14 Hydraulic system - bleeding(anti-lock braking system) 3Note: Before starting work, refer to thewarning at the beginning of Section 13concerning the dangers of hydraulic fluid.1 On vehicles equipped with the anti-lockbraking system there are two bleedprocedures possible, depending on whichpart of the brake hydraulic system has beendisturbed.2 If any one of the following conditions arepresent, bleed procedure A should beadopted:a) A modulator has been removed.b) A modulator return hose (betweenmodulator and brake fluid reservoir) hasbeen drained.c) The rigid brake pipes have beendisconnected from a modulator.3 If any one of the following conditions arepresent, bleed procedure B should beadopted:a) Any condition where the master cylinderhas been removed or drained, providingthat the modulator return hoses have notlost their head of fluid.b) Removal or disconnection of any of thebasic braking system components ie,brake caliper, flexible hose or rigid pipe,wheel cylinder, or load-apportioningvalve.Bleed procedure A4 Raise the vehicle on ramps, or drive it overan inspection pit, so that working clearancemay be obtained with the full weight of thevehicle on its roadwheels. Remove the onepieceundertray, as applicable, by turning itsbayonet-type fasteners and, on XR2i models,remove the front suspension crossmember(see Chapter 10).5 Disconnect the wiring multi-plug from thefluid level warning indicator in the mastercylinder reservoir filler cap, then remove thefiller cap. Note that the filler cap must not beinverted. Top-up the brake fluid reservoir tothe MAX mark using fresh fluid of thespecified type (see “Weekly Checks”), andkeep it topped up throughout the bleedingprocedure.6 Slacken the modulator bypass valve Torxscrew, located between the two rigid brakepipe connections on the modulator body, andunscrew it two full turns (see illustration).7 Fully depress the auto-bleed plunger on themodulator and hold it down so that theplunger circlip contacts the modulator body(see illustration). With the plungerdepressed, have an assistant steadily pumpthe brake pedal at least twenty times whilstyou observe the fluid returning to the brakefluid reservoir. Continue this operation untilthe returning fluid is free from air bubbles.8 Release the auto-bleed plunger, ensuringthat it returns to its normal operationalposition - pull it out by hand if necessary.9 Tighten the modulator bypass valve Torxscrew.10 Repeat the operation on the othermodulator, if applicable, then refit the onepieceundertray and the front suspensioncrossmember if removed.11 Now carry out bleed procedure B.Bleed procedure B12 This procedure is the same as forconventional braking systems, and referenceshould be made to Section 13. Note,however, that all the weight of the vehiclemust be on the roadwheels, otherwise theload-apportioning valves will not bleed. Ifproblems are encountered whereby the rearbrakes will not bleed satisfactorily, ensure thatthe load-apportioning valves are correctlyadjusted (see Section 25). As with theconventional braking system, the brake fluidlevel must be kept topped up during bleeding.15 Vacuum servo unit - testing,removal and refitting3Testing1 To test the operation of the servo, depressthe footbrake four or five times to exhaust thevacuum, then start the engine while keepingthe footbrake depressed. As the engine starts,there should be a noticeable “give” in thebrake pedal as vacuum builds up. Allow theengine to run for at least two minutes, andthen switch it off. If the brake pedal isdepressed again, it should be possible todetect a hiss from the servo when the pedal isdepressed. After about four or fiveapplications, no further hissing will be heard,and the pedal will feel considerably firmer.2 Before assuming that a problem exists inthe servo itself, check the non-return valve asdescribed in the next Section.Removal3 Refer to Section 9 and remove the mastercylinder.4 Disconnect the vacuum hose at the servonon-return valve by pulling it free. If it isreluctant to move, assist it by prising it freeusing a screwdriver with its blade insertedunder the elbow flange.5 Lift up the flap of sound insulation on thebulkhead, in the passenger side footwell, toexpose the servo mounting bracket retainingnuts (see illustration 11.6). Remove the twoinnermost nuts to free the inner section of theservo mounting bracket from its bulkhead14.6 Modulator bypass valve Torx screw(arrowed)14.7 Modulator auto-bleed plunger(arrowed)91595Ford Fiesta Remake