Chapter 1 Routine maintenance and servicing

1595Ford Fiesta Remake2D•14 Engine removal and overhaul procedures7.21a Ford service tool in use to removevalve spring lower seat/stem oil seals . . .draw the seal off the valve guide (seeillustrations).22 It is essential that the valves are kepttogether with their collets, spring seats andsprings, and in their correct sequence (unlessthey are so badly worn that they are to berenewed). If they are going to be kept andused again, place them in a labelled polythenebag or similar small container (see illustration7.9). Note that No 1 valve is nearest tothe timing belt end of the engine.23 If the oil-retaining valve is to be removed(to flush out the cylinder head oil galleriesthoroughly), seek the advice of a Ford dealeras to how it can be extracted; it may bethat the only course of action involvesdestroying the valve as follows. Screw a selftappingscrew into its ventilation hole, and usethe screw to provide purchase with which thevalve can be drawn out; a new valve must bepurchased and pressed into place onreassembly (see illustration).8 Cylinder head and valvecomponents - cleaning andinspection41 Thorough cleaning of the cylinder head andvalve components, followed by a detailedinspection, will enable you to decide howmuch valve service work must be carried outduring the engine overhaul. Note: If the8.6 Check the cylinder head gasketsurfaces for warpage, in the planesindicated (A to G)7.21b . . . can be replaced by home-madetool if suitable spring can be foundengine has been severely overheated, it is bestto assume that the cylinder head is warped,and to check carefully for signs of this.Cleaning2 Scrape away all traces of old gasketmaterial and sealing compound from thecylinder head.3 Scrape away the carbon from thecombustion chambers and ports, then washthe cylinder head thoroughly with paraffin or asuitable solvent.4 Scrape off any heavy carbon deposits thatmay have formed on the valves, then use apower-operated wire brush to removedeposits from the valve heads and stems.InspectionNote: Be sure to perform all the followinginspection procedures before concluding thatthe services of a machine shop or engineoverhaul specialist are required. Make a list ofall items that require attention.Cylinder head5 Inspect the head very carefully for cracks,evidence of coolant leakage, and otherdamage. If cracks are found, a new cylinderhead should be obtained.6 Use a straight edge and feeler blade tocheck that the cylinder head gasket surface isnot distorted (see illustration). If it is, it maybe possible to re-surface it.7 Examine the valve seats in each of thecombustion chambers. If they are severely8.12 Measuring the diameter of a valvestem7.23 Cylinder head oil-retaining valve(arrowed)pitted, cracked or burned, then they will needto be renewed or re-cut by an engine overhaulspecialist. If they are only slightly pitted, thiscan be removed by grinding-in the valveheads and seats with fine valve-grindingcompound, as described below.8 If the valve guides are worn, indicated by aside-to-side motion of the valve, new guidesmust be fitted. Measure the diameter of theexisting valve stems (see below) and the boreof the guides, then calculate the clearance,and compare the result with the specifiedvalue; if the clearance is excessive, renew thevalves or guides as necessary.9 The renewal of valve guides is best carriedout by an engine overhaul specialist.10 If the valve seats are to be re-cut, thismust be done only after the guides have beenrenewed.Valves11 Examine the head of each valve forpitting, burning, cracks and general wear, andcheck the valve stem for scoring and wearridges. Rotate the valve, and check for anyobvious indication that it is bent. Look for pitsand excessive wear on the tip of each valvestem. Renew any valve that shows any suchsigns of wear or damage.12 If the valve appears satisfactory at thisstage, measure the valve stem diameter atseveral points, using a micrometer (seeillustration). Any significant difference in thereadings obtained indicates wear of the valvestem. Should any of these conditions beapparent, the valve(s) must be renewed.13 If the valves are in satisfactory condition,they should be ground (lapped) into theirrespective seats, to ensure a smooth gastightseal. If the seat is only lightly pitted, or ifit has been re-cut, fine grinding compoundonly should be used to produce the requiredfinish. Coarse valve-grinding compoundshould not be used unless a seat is badlyburned or deeply pitted; if this is the case, thecylinder head and valves should be inspectedby an expert, to decide whether seat recutting,or even the renewal of the valve orseat insert, is required.14 Valve grinding is carried out as follows.Place the cylinder head upside-down on a