Friday, October18, 2019

'cav Pintaux Injection Nozzle Rebuild'


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Section C.6
                  FUEL INJECTORS
   The 2.2-litre diesel engine is fitted with a special
injection nozzle known as the Pintaux type which has
been developed primarily to give easy starting from cold.
A feature of this nozzle is that on cold startingit directs
the fuel spray through an auxiliary hole to the hottest
zone of the combustion chamber.
  In operation, the pressure in the annulus builds up
during the pump delivery, lifting the needle from its
seating and permitting a flow of fuel into the annulus
below the seat from which the auxiliary hole leads.
The needle is extended below the seat to fit into the
comparatively large-diameter pintle hole. At starting
speeds the needle is not lifted sufficiently to clear the
pintle hole and the bulk of the fuel is therefore dis-
charged through the auxiliary or starting hole. At normal
running speeds, when the pressure in the fuel system is
higher, the needle is withdrawn from the pintle hole in
the normal manner. A small proportion of fuel continues

                       Fig. C.13
                The C.A. V. Pintaux nozzle
                         THE FUEL SYSTEM ('In-line' Injection Pump)

to be discharged through the auxiliary hole, which               10 seconds and examine the nozzle seat for dryness.
prevents carbon formation therein and does not affect            Reject if wet. If in doubt, maintain this pressure for a
engine performance adversely.                                    period of 60 seconds, when the diameter of the wet spot
                                                                 on a piece of blotting-paper held below the nozzle tip
Nozzle-testing                                                   must not exceed 3 in. (13 mm.).
    If the injector nozzles are to be tested correctly or it     3. Back-leakage test
is desired to adjust the opening pressure, then the use of         The pressure gauge of the injector testing machine
nozzle-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 in
handling the injectors, such as Shell Calibration Fluid          paragraph 4.
'C', should be used; the oil has about the same viscosity          Operate the lever of the testing machine until the
as diesel oil and also prevents stickiness of the needle         gauge registers a pressure of 160 atmospheres. Release
after 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 time
tank is full. There is no necessity for air-venting as the       should not be less than six seconds nor greater than 40         i
pump is self-priming.                                            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 a
close the check valve to prevent damage to the pressure          somewhat lower figure may be obtained.
gauge, which may result from a sudden drop in pressure.            When carrying out this test ensure that no leakage            t
    WARNING.-It cannot be stressed too strongly that             occurs at the lapped joint of the valve. If leakage at
when a nozzle is spraying the nozzle holder must be turned       the lapped joint is suspected, do not overtighten the cap
away 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 in
necessary to use a special test adaptor, 18G 109 B, which        order replace the components and re-test. If the pressure
is connected between the injector testing machine and the        drop time is still low, this indicates excessive leakage past
injector under test. The adaptor consists of an additional       the lapped portion of the valve. Nozzles not passing the
nozzle holder fitted with a special nozzle, and a modified       above test should be renewed complete.
cap nut, into which the injector under test is fitted. The       4. To check and adjust the nozzle opening pressure
adaptor assembly is used to simulate high rates of                 After carrying out the foregoing tests the Pintaux
injection 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 follows:
set to an opening pressing of 220 atmospheres. A fine              (a) Remove the injector from the testing machine.
spray formation from the test adaptor must not be                  (b) Remove the injector cap nut and copper joint,,
expected 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 anti-clockwise to reduce
 gauge and operate the test machine several times to expel               the opening pressure.
 any air.                                                          (d) Lock the spring cap nut and re-check 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 minute-the 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
  C.18                                                                                                  Taxi. Issue 5. 73082
                            THE FUEL SYSTEM (In-line' Injection Pump)
                                                                    time the fuel feed unions should be sealed with sealing
                                                                    caps 18G216.
                                                                      The nozzle should then be wrapped in greaseproof
                                                                    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.
                                                                       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.                       NOTE.--The 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 cleaning
releasing the piping union nut on each nozzle holder in
                                                                    kit 18G 487.
turn while the engine is running and listening to the                  Remove any carbon from the valve, using the brass
idling 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 a
described below and refit to its fuel feed pipe so that the         scratch or a burr may cause leakage or spray distortion.
nozzle is pointing outwards, away from the engine.                  All polished surfaces should be relatively bright and
Slacken the unions of the other nozzle fuel feed pipes              should not appear `blue' due to overheating.
(to prevent fuel being sprayed into the cylinders). Using             Using the wire brush, remove all loose carbon from
the starter, turn the engine until the suspect nozzle sprays        the outside of the nozzle. Clear the pintle orifice by
into the air. If the spray is unduly wet or streaky, or             passing a suitably sized probe down the nozzle bore
obviously to one side, or the nozzle dribbles, renew the
complete unit (nozzle and nozzle holder).
   NOTE.-    The nozzle holder must be turned away from
the operator and the hands must not be allowed to come
into contact with the fuel spray, as the injection pressure
will cause oil to penetrate the skin with ease.

To remove
   Nozzles should be removed from the engine and
examined at regular intervals, the frequency of attention
being as recommended in the Driver's Handbook.
   Disconnect the injector feed pipe and all the injector
leak-off unions.
   Remove the two nuts securing the injector to the
cylinder head and withdraw the injector, using tool
18G 491 A. Immediately plug the hole in the cylinder
head to prevent the ingress of foreign matter.                                             Fig. C.15
   If the injectors are to be removed for any length of               Withdrawing an injector nozzle, using tool 18G 491 A
Taxi. Issue4. 73082                                                                                                        c.19
C                       THE FUEL SYSTEM (`In-line' 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 build-up 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. (56.7 gm.)
                                                               of caustic soda in 1 pint (,57 litre) of water and add 3 oz.
                                                               (14.2 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. C.17         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 de-watering 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. C.18                                                   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 spindle
until it protrudes through the orifice. Rotate the probe       should be perfectly smooth and straight. Examine the
until 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 clear
in the fuel gallery (see Fig. C.16). Press hard against the    and free from abnormal wear. Clear out the feed hole in
side of the cavity and rotate to clear away all carbon         the nozzle holder, using an air jet; the copper seating of
deposit.                                                       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 nozzle
probe down the nozzle bore until it protrudes through the      holder, which should be perfectly smooth and flat.
orifice (see Fig. C.17). Rotate the probe until all the
carbon is removed.                                             To reassemble
   With the seat scraper clean all carbon from the valve         Thoroughly wash the nozzle body and needle valve in
seating (Fig. C.18) by rotating and pressing the tool onto     Shell Calibration Fluid `C` and test the fit of the valve in
the seating.
   Clear the auxiliary spray hole by use of the probing
tool fitted with the appropriate size cleaning wire (Fig.                                                Fig. C.19
C.19). The wire should be fitted into the tool so that it
                                                                                                      Clearing the
protrudes only approximately & in. (1.6 mm.) to give
                                                                                                      auxiliary spray
maximum resistance to bending. Extreme care must be
exercised to obviate the danger of wires breaking in the
hole, as broken particles are extremely difficult to remove.
   Clean out the small feed channel bores, as shown in
Fig. C.20, with a drill or wire of -067 in. (1.7 mm.)
   Ensure that the lapped pressure faces on the upper              Fig. C.20
end of the nozzle are clean, perfectly smooth, and free
                                                               Cleaning the feed
from burrs.
                                                                 channel bores
   Assemble the nozzle into adaptor 18G 109 E with the
nozzle end towards the small thread connection (see
Fig. C.21). Attach the adaptor to testing machine
c.20                                                                                                  Taxi. Issue4. 73082
                        THE FUEL SYSTEM ('In-line' 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 back-leakage 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 centre-line of the
                                                                 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 nozzle-testing machine. If (3) is leaking,
                                                               then the valve will either stick open or an excessive
                         Fig. C.21
                                                               amount of oil will leak back from the nozzle holder
  Reverse-flushing an injector nozzle with testing             leak-off 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, and/or
                                                               pintle and orifice, is excessive, then the nozzle should be
the nozzle body. The valve should just fall into position
under 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 the
Fluid '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 render
parts 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 becomes
in the vice. Make sure that the pressure faces of the          ineffective.
holder and nozzle body are perfectly clean. Place the             Assuming that it has been determined that the nozzle
nozzle assembly in position on the holder, ensuring that       is dribbling or spraying badly due to lack of quality
the 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 of
ratchet. Do not overtighten this nut, since distortion and             nozzle should be selected. It should be noted that
subsequent 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 the
grease to prevent rusting. Replace the spring cap nut,                 nozzle body in the same manner as the needle
locknut, 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 in
described on page C. 18, and, if the nozzle is to be stored,           diameter, but the operator will be able to determine
lightly smear it with grease before packing.                           the correct fit by feel.
                                                                  (2) Mount the lap in the lathe of the nozzle grinding
To 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. Remove
Replace 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 hole.
the securing nuts and tighten evenly to a torque of               (3) Fit the lap into the lapping chuck of the machine
12 lb. ft. (1.6 kg. m.).                                               and apply a coating of tallow to the lap guide
  Connect the fuel feed pipe and leak-off unions.                      surface for lubrication purposes. With a match-
                                                                       stick apply a fine speck of lapping paste to the
                                                                       conical tip of the lap.
Nozzle reclamation
  Clean the nozzles in the normal manner. If they are                  NOTE.-Take care to keep all lapping paste off
then not satisfactory it is probably due to faulty seats             the sides (i.e. restrict it to the extreme tip) as
caused by scoring or wear. The fundamental require-                  otherwise the bore of the body will be increased and
ments of the nozzle operation are:                                   thus too much clearance will exist between the valve
  (1) Oil-tight seating.                                             and body, causing excessive back-leakage.
Taxi. Issue 6. 73082                                                                                                 c.21
C                    THE FUEL SYSTEM ('In-line' Injection Pump)                                                                I

(4) 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                 high-pressure 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.
       NOTE.--The lap must be refaced, as described
    in paragraph (2), after every 13 minutes of lapping
    Thoroughly clean the nozzle by reverse-flushing;
    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. C.22
    nozzle grinding and lapping machine.
                                                                             The oil-bath-type air cleaner
    Ensure that the grinding-wheel 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 grinding-wheel which will be                    described on pages C.18, C.19, C.20, and C.21.
    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, i.e. 60.
       NOTE.-Remove only the absolute minimum of
    material; sufficient to change the colour of the valve    Section C.7
    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 grinding-wheel 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

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