Section C6 FUEL The 22litre diesel engine is fitted with a nozzle known as the Pintaux type which hasbeen developed primarily to give easy starting from coldA feature of this nozzle is that on cold startingit directsthe fuel spray through an auxiliary hole to the hottestzone of the combustion chamber In operation the pressure in the annulus builds upduring the pump delivery lifting the needle from itsseating and permitting a flow of fuel into the annulusbelow the seat from which the auxiliary hole leadsThe needle is extended below the seat to fit into largediameter pintle hole At startingspeeds the needle is not lifted sufficiently to clear thepintle hole and the bulk of the fuel is therefore discharged through the auxiliary or starting hole At normalrunning speeds when the pressure in the fuel system ishigher the needle is withdrawn from the pintle hole inthe normal manner A small proportion of fuel continues I I 1 9010 Fig C13 The CA V Pintaux nozzle C17 THE FUEL SYSTEM Inline Injection Pumpto be discharged through the auxiliary hole which 10 seconds and examine the nozzle seat for carbon formation therein and does not affect Reject if wet If in doubt maintain this pressure for aengine performance adversely period of 60 seconds when the diameter of the wet spot on a piece of blottingpaper held below the nozzle must not exceed 3 in 13 mm If the injector nozzles are to be tested correctly or it 3 Backleakage testis desired to adjust the opening pressure then the use of The pressure gauge of the injector testing machine 18G 109 A is necessary must be in circuit and the injector under test set to open A fuel which does not affect the skin of the person at between 160 and 170 atmospheres as described inhandling the injectors such as Shell Calibration Fluid paragraph 4C should be used the oil has about the same viscosity Operate the lever of the testing machine until theas diesel oil and also prevents stickiness of the needle gauge registers a pressure of 160 atmospheres Releaseafter long periods of injector storage the lever and time the pressure drop from 150 to 100 Before using this testing machine ensure that the fuel atmospheres For a nozzle in good condition this timetank is full There is no necessity for airventing as the should not be less than six seconds nor greater than 40 ipump is selfpriming seconds using Shell Calibration Fluid C at a temperature Before removing an injector from the testing machine of 10 to 21 C 50 to 70 F At higher temperatures aclose the check valve to prevent damage to the pressure somewhat lower figure may be obtainedgauge which may result from a sudden drop in pressure When carrying out this test ensure that no leakage t WARNINGIt cannot be stressed too strongly that occurs at the lapped joint of the valve If leakage atwhen a nozzle is spraying the nozzle holder must be turned the lapped joint is suspected do not overtighten the capaway from the operator nut in an effort to rectify but remove the nozzle and re 1 Testing for spray examine the pressure faces for signs of dirt or surface In order to test this type of nozzle for spray it is imperfections Clean thoroughly and if all appears innecessary to use a special test adaptor 18G 109 B which order replace the components and retest If the pressureis connected between the injector testing machine and the drop time is still low this indicates excessive leakage pastinjector under test The adaptor consists of an additional the lapped portion of the valve Nozzles not passing thenozzle holder fitted with a special nozzle and a modified above test should be renewed completecap nut into which the injector under test is fitted The 4 To check and adjust the nozzle opening assembly is used to simulate high rates of After carrying out the foregoing tests the so that the main spray can be observed nozzle must be set to open at a pressure of 115 atmo Attach adaptor 18G 109 B to the testing machine and spheres as followsset to an opening pressing of 220 atmospheres A fine a Remove the injector from the testing machinespray formation from the test adaptor must not be b Remove the injector cap nut and copper jointexpected in view of its special nozzle washer Now screw the Pintaux injector to be tested into the c Release the locknut and turn the spring cap nut test adaptor close the check valve to cut off the pressure clockwise to increase or anticlockwise to reduce gauge and operate the test machine several times to expel the opening pressure any air d Lock the spring cap nut and recheck the nozzle a Auxiliary spray With the pressure gauge out of opening pressure on the testing machine circuit operate the testing machine slowly at about e Repeat operations c and d until the correct 60 strokes a minute it is possible to cut out the opening pressure of 115 atmospheres is obtained main spray almost entirely and produce only the f Refit the injector cap nut and joint washer auxiliary spray When this condition has been achieved the auxiliary spray can be observed This Fault diagnosis and rectification should be well formed and free from splits and The first symptoms of nozzle trouble usually manifest distortions although there may be present a slight themselves under one or more of the following occur central core which may be disregarded rences b Main spray Operating the hand lever more rapidly 1 Cylinder knock 2 Engine overheating at about 140 strokes per minutethe main spray 3 Loss of power 4 Smoky black exhaust can be observed The same remarks apply to its 5 Increased fuel consumption formation as in a above It should not be immediately assumed that the nozzles 2 Seat tightness test are faulty for such features as incorrect engine valve Remove the test adaptor and connect me injector timing leaking valves incorrect pump timing dirty or under test direct to the injector testing machine Open damaged fuel filters wrong fuel or water in fuel defective the check valve and set the nozzle to an opening pressure engine lubrication or incorrect fuel pump maximum fuel of 115 atmospheres as described in paragraph 4 setting may give rise to similar symptoms Depress the lever of the testing machine until a pressure With all other possible causes eliminated the particular of 105 atmospheres is obtained Hold this pressure for nozzle giving trouble can usually be determined by C18 Taxi Issue 5 73082 THE FUEL SYSTEM Inline Injection Pump time the fuel feed unions should be sealed with sealing caps 18G216 The nozzle should then be wrapped in greaseproof I paper 2 To dismantle 3 As in the case of injection pump dismantling absolute cleanliness is essential therefore the same facilities must 4 be available and the same precautions taken for injector maintenance as those described at the beginning of the Section for the injection pump 5 Fit the injector in the dismantling fixture 18G 388 and secure in a vice Unscrew the injector cap nut and remove the copper joint washer 6 Release the locknut and unscrew the spring cap nut Remove the copper joint washer spring and spindle If the complete dismantling of the nozzle holder and 8 nozzle is being carried out remove the fuel inlet union A1793 early injectors only Unscrew the nozzle nut using spanner 18G 210 which Fig C 14 is used in conjunction with a standard ratchet wrench A fuel injector Remove the nozzle body taking care not to let the needle 1 Injector cap nut 8 Nozzle valve valve drop out 2 Cap nut washer 9 Spindle NOTEThe nozzle components are mated and must 3 Locknut 10 Inlet union always be kept together 4 Locknut washer 11 spring 5 Nozzle holder 12 Washer 6 Nozzle nut 13 Spring cap nut To view and overhaul 7 Nozzle body Nozzles All the tools required for the cleaning operations set out in the following paragraphs are contained in the piping union nut on each nozzle holder in kit 18G 487turn while the engine is running and listening to the Remove any carbon from the valve using the brassidling performance of each of the other cylinders wire brush and polish with a piece of soft wood Use To test a doubtful nozzle remove the injector as considerable care when cleaning the needle valve as adescribed below and refit to its fuel feed pipe so that the scratch or a burr may cause leakage or spray is pointing outwards away from the engine All polished surfaces should be relatively bright andSlacken the unions of the other nozzle fuel feed pipes should not appear blue due to overheatingto prevent fuel being sprayed into the cylinders Using Using the wire brush remove all loose carbon fromthe starter turn the engine until the suspect nozzle sprays the outside of the nozzle Clear the pintle orifice byinto the air If the spray is unduly wet or streaky or passing a suitably sized probe down the nozzle boreobviously to one side or the nozzle dribbles renew thecomplete unit nozzle and nozzle holder NOTE The nozzle holder must be turned away fromthe operator and the hands must not be allowed to comeinto contact with the fuel spray as the injection pressurewill cause oil to penetrate the skin with easeTo remove Nozzles should be removed from the engine andexamined at regular intervals the frequency of attentionbeing as recommended in the Drivers Handbook Disconnect the injector feed pipe and all the unions Remove the two nuts securing the injector to thecylinder head and withdraw the injector using tool18G 491 A Immediately plug the hole in the cylinderhead to prevent the ingress of foreign matter Fig C15 If the injectors are to be removed for any length of Withdrawing an injector nozzle using tool 18G 491 ATaxi Issue4 73082 c19C THE FUEL SYSTEM Inline Injection Pump 18G 109 A and operate the pumping lever several times This forces oil through the spray holes in the reverse direction and flushes out the gallery and internal passages Fig C 16 to remove any loose carbon Cleaning the In cases where the carbon buildup is particularly hard carbon from the this may be softened in the following manner thereby fuel gallery reducing time prepare a 10 per cent solution of caustic soda with a detergent added by dissolving 2 oz 567 gm of caustic soda in 1 pint 57 litre of water and add 3 oz 142 gm of an ordinary washing detergent Place the nozzle bodies in the liquid and bring it to the boil for a minimum of 1 hour and not more than 13 hours Care must be taken not to allow the water to evaporate too Fig C17 much because if the percentage of caustic soda rises Clearing the above 15 per cent the surface of the guide bore and seal pintle orifice may be roughened making it impossible to service the injectors correctly Remove the nozzle bodies from the solution wash them in running water and then immerse them in a dewatering oil such as Shell Ensis 254 Remove the surplus oil by draining or compressed air The carbon may now be removed using the standard tools provided in the cleaning kit or in some cases blown clean with compressed air Fig C18 If the nozzle is blued or the seating has a dull circum Cleaning the ferential ring indicating wear or pitting the complete unit nozzle seating should be set aside for special attention See under Nozzle reclamation Nozzle holders Wash all the components in clean paraffin Examine the spring for signs of weakness rusting or fracture Ensure that the ends are perfectly square The spindleuntil it protrudes through the orifice Rotate the probe should be perfectly smooth and straight Examine theuntil all the carbon is removed recessed end of the spindle which accommodates the top Insert the special groove scraper until the nose locates of the nozzle valve the recess should be perfectly clearin the fuel gallery see Fig C16 Press hard against the and free from abnormal wear Clear out the feed hole inside of the cavity and rotate to clear away all carbon the nozzle holder using an air jet the copper seating ofdeposit the feed pipe union must be in good condition Clean the pintle orifice by passing a suitably sized Examine the bottom pressure facing of the nozzleprobe down the nozzle bore until it protrudes through the holder which should be perfectly smooth and flatorifice see Fig C17 Rotate the probe until all thecarbon is removed To reassemble With the seat scraper clean all carbon from the valve Thoroughly wash the nozzle body and needle valve inseating Fig C18 by rotating and pressing the tool onto Shell Calibration Fluid C and test the fit of the valve inthe seating Clear the auxiliary spray hole by use of the probingtool fitted with the appropriate size cleaning wire Fig Fig C19C19 The wire should be fitted into the tool so that it Clearing theprotrudes only approximately in 16 mm to give auxiliary spraymaximum resistance to bending Extreme care must be holeexercised to obviate the danger of wires breaking in thehole as broken particles are extremely difficult to remove Clean out the small feed channel bores as shown inFig C20 with a drill or wire of 067 in 17 mmdiameter Ensure that the lapped pressure faces on the upper Fig C20end of the nozzle are clean perfectly smooth and free Cleaning the feedfrom burrs channel bores Assemble the nozzle into adaptor 18G 109 E with thenozzle end towards the small thread connection seeFig C21 Attach the adaptor to testing machinec20 Taxi Issue4 73082 THE FUEL SYSTEM Inline Injection Pump C 2 Correct angular fitment of the nozzle body and nozzle valve seat 3 Good fitting of the valve in the body it must be able to move perfectly freely yet not permit excessive backleakage of fuel oil 4 The clearance between the pintle and the spray hole must not be excessive If the nozzle is taken out and the pintle end reversed and inserted in the orifice or spray hole it should not tilt at a greater angle than about 20 from the centreline of the body Assuming correct adjustment of opening pressure a nozzle lacking the conditions required in l 2 or 4 will have a distorted or wet spray leaking seat etc when tested on a nozzletesting machine If 3 is leaking then the valve will either stick open or an excessive Fig C21 amount of oil will leak back from the nozzle holder an injector nozzle with testing leakoff connection This will also be shown by the rapid machine 18G 109 A and udaptor 18G 109 E Shown return of the needle in the pressure gauge of the nozzle inset is a sectioned adaptor with a nozzle in position testing machine If the clearance between the needle and body andor pintle and orifice is excessive then the nozzle should bethe nozzle body The valve should just fall into positionunder its own weight when lubricated with fuel oil scrapped Similarly units must be scrapped if damage Immerse both in a bowl of clean Shell Calibration has been sustained at the pintle end or lapped face of theFluid C and assemble under the liquid nozzle body or the needle valve Finally the appearance Thoroughly wash the nozzle holder and component of fuel abrasion at the top of the seat core may renderparts in Shell Calibration Fluid C the nozzle unrepairable This sometimes has the effect Mount the nozzle holder in fixture 18G 388 and secure of rounding off the seat angle thus lapping becomesin the vice Make sure that the pressure faces of the and nozzle body are perfectly clean Place the Assuming that it has been determined that the nozzlenozzle assembly in position on the holder ensuring that is dribbling or spraying badly due to lack of qualitythe dowels locate in the holes 1 or 2 above then the seat should be relapped as Fit the nozzle nut and tighten carefully using spanner follows 18G210 which is used in conjunction with a standard 1 A lap of suitable diameter according to size ofratchet Do not overtighten this nut since distortion and nozzle should be selected It should be noted thatsubsequent seizure of the nozzle may result the nozzle bore varies slightly in diameter and it Reassemble the spring and spindle using a smear of is necessary to choose a lap which will fit thegrease to prevent rusting Replace the spring cap nut nozzle body in the same manner as the needlelocknut and copper joint washer valve This will ensure concentricity of the body Fit the cap nut with its copper joint washer seat after lapping As a guide it will be found that Test the injector for spray and opening pressure as new laps have a marking indicating a variation indescribed on page C 18 and if the nozzle is to be stored diameter but the operator will be able to smear it with grease before packing the correct fit by feel 2 Mount the lap in the lathe of the nozzle grindingTo install and lapping machine and grind the conical tip to Thoroughly clean the aperture in the cylinder head the correct nozzle seat angle of 59 RemoveReplace the copper sealing washer the extreme tip of the lap to prevent damage to the Place the injector in position in the cylinder head fit pintle holethe securing nuts and tighten evenly to a torque of 3 Fit the lap into the lapping chuck of the machine12 lb ft 16 kg m and apply a coating of tallow to the lap guide Connect the fuel feed pipe and leakoff unions surface for lubrication purposes With a match stick apply a fine speck of lapping paste to the conical tip of the lapNozzle reclamation Clean the nozzles in the normal manner If they are NOTETake care to keep all lapping paste offthen not satisfactory it is probably due to faulty seats the sides ie restrict it to the extreme tip ascaused by scoring or wear The fundamental require otherwise the bore of the body will be increased andments of the nozzle operation are thus too much clearance will exist between the valve 1 Oiltight seating and body causing excessive Issue 6 73082 c21C THE FUEL SYSTEM Inline Injection Pump I4 Start the machine and slide the nozzle carefully 13 Using a suitably adapted dial gauge check the over the rotating lap ensuring that the lapping needle lift which should be 032 to 038 in 80 to paste does not contact the bore of the nozzle mm Oscillate the nozzle over the lap using short If the needle lift is found to be in excess of these strokes and engage the lap with the nozzle seat at limits it can be restored by lapping the top face of the end of each stroke The lap should not remain the nozzle body on a surface lapping plate in contact with the nozzle seat for more than five When lapping the nozzle face extreme care must seconds at a time be taken not to tilt the nozzle as this face makes a After 30 seconds withdraw the nozzle clean the highpressure joint with the nozzle holder and must lap and examine its conical tip which will have a therefore be true and at right angles to the nozzle mat surface where it has made contact with the axis nozzle seat In the early stages of lapping the width of this mat surface will probably be narrow or may have a bright ring in the middle which indicates the extent of the wear on the nozzle seat Continue lapping as above examining the lap every 30 seconds until a mat surface over the majority of the lap conical tip is obtained NOTEThe lap must be refaced as described in paragraph 2 after every 13 minutes of lapping time Thoroughly clean the nozzle by dry out with compressed air and examine its seating through a nozzle microscope The seat must be free from scores and pitting Examine the needle valve conical tip under the nozzle microscope for scoring and pitting If wear is evident the valve tip must be refaced on the Fig C22 nozzle grinding and lapping machine The oilbathtype air cleaner Ensure that the grindingwheel has been dressed and is perfectly true To prevent damage to the pintle when refacing a Pintaux needle valve dress 14 Reassemble test and set the injector nozzle as the edge of the grindingwheel which will be described on pages C18 C19 C20 and C21 adjacent to the pintle to an angle of 45 It w i l l be found that owing to the lowering of the Mount the needle valve in the lathe of the machine seating in the nozzle body that it is impracticable to and reface the valve conical tip at the correct reclaim a nozzle more than three times angle ie 60 NOTERemove only the absolute minimum of material sufficient to change the colour of the valve Section C7 tip is all that is necessary otherwise the needle lift will be affected As a guide there must be no sparks AIR CLEANER or audible hiss from the grindingwheel when carry To remove and dismantle ing out this operation Drain clean and refill the air cleaner at the recom In the event of the needle being a tight fit in the mended intervals These periods must be reduced if nozzle body due to slight distortion or deposits on excessive sludge accumulates in the base of the cleaner the valve guide surface it is possible to restore the Sludge must not be allowed to exceed 3 in 13 mm fit using the adjustable collet provided as part of in depth Proceed as follows the equipment supplied with the nozzle grinding Release the two rubber hoses from the air cleaner and lapping machine Remove the bolts securing the air cleaner to its Mount the needle valve in the lapping chuck and supports and withdraw it taking care to avoid spilling apply a very small quantity of fine lapping paste to the oil the valve guide surface Start the machine and thread the lapping collet over the rotating valve To view and overhaul Oscillate the collet over the valve guide surface Wash the filter element thoroughly in petrol and allow and after every 10 to 15 seconds of lapping time it to dry out clean the valve and test it for correct fit in the Empty the container base and clean out all oil and nozzle body A correctly fitting needle valve will sludge just slide into the nozzle body under its own weight Refill the container with new engine oil up to the level when lubricated with fuel oil indicated Taxi Issue 6 73082