Tuesday, June19, 2018 L-36.com

'cav Pintaux Injection Nozzle Rebuild'

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Section C6
FUEL The 22litre diesel engine is fitted with a 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 pintle hole At 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 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higher the needle is withdrawn from the pintle hole in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 C13
The CA V Pintaux nozzle
THE FUEL SYSTEM Inline Injection Pump
to 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 a
engine performance adversely period of 60 seconds when the diameter of the wet spot
on a piece of held below the nozzle must not exceed 3 in 13 mm
If the injector nozzles are to be tested correctly or it 3 Backleakage test
is 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 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 airventing as the should not be less than six seconds nor greater than 40 i
pump 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 a
close the check valve to prevent damage to the pressure somewhat lower figure may be 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 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 Clean thoroughly and if all appears in
necessary to use a special test adaptor 18G 109 B which order replace the components and retest 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 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 follows
set to an opening pressing of 220 atmospheres A fine a Remove the injector from the testing formation from the test adaptor must not be
b Remove the injector cap nut and copper 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 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 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
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 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 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 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 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 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 as recommended in the Drivers Handbook
Disconnect the injector feed pipe and all the 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 C15
If the injectors are to be removed for any length of Withdrawing an injector nozzle using tool 18G 491 A
Taxi Issue4 73082 c19
C 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 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 C16 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 C17 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 C18 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 C19
C19 The wire should be fitted into the tool so that it
Clearing the
protrudes only approximately in 16 mm to give
auxiliary spray
maximum resistance to bending Extreme care must be
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 C20 with a drill or wire of 067 in 17 Ensure that the lapped pressure faces on the upper Fig C20
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 C21 Attach the adaptor to testing machine
c20 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
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 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 be
the nozzle body The valve should just fall into its own weight when lubricated with fuel oil scrapped Similarly units must be scrapped if
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 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 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 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 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 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 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 lap
Nozzle reclamation
Clean the nozzles in the normal manner If they are NOTETake care to keep all lapping paste off
then not satisfactory it is probably due to faulty seats the sides ie 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 Oiltight seating and body causing excessive Issue 6 73082
C THE FUEL SYSTEM Inline 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 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
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 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 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 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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