ALLIS-CHALMERS
day, prior to starting the engine. The
fuel then flows to the renewable ele-
ment type primary filter (B). The
drain cock (C) at the bottom of the
primary filter should be opened and
a small quantity of fuel drained each
day, prior to starting the engine. From
the primary filter, the fuel passes
through the transfer pump (C—Fig.
AC61) to the renewable element type
intermediate filter (E). If any signs
of water are apparent when draining
fuel from the primary filter, a small
quantity of fuel must be drained from
the intermediate filter.
The fuel then passes through the
secondary (or final) sealed-type filter
(F) and into the injection pump sump.
The secondary (or final) filter must
be renewed as a unit.
The fuel transfer pump, pumps fuel
through the intermediate and second-
ary (or final) filters under a normal
pressure of 15 psi,
147B.
To check the filters and/or
the transfer pump, install a suitable
pressure gage in series between the
secondary (or final) fuel filter outlet
and the injection pump fuel inlet.
Start the engine and observe the pres-
sure gage reading. The gage should
register at least 5 psi. If the gage read-
ing is low, renew the intermediate
stage element and recheck pressure
reading. If the gage reading is still
low, renew the complete secondary
(or final) filter and recheck the pres-
sure reading. If the gage reading is
still low, the transfer pump is not
operating properly and same should
be renewed and/or overhauled. Refer
to paragraph 150A.
INJECTION NOZZLES
WARNING:
Fuel leaves
the
injection
noz-
zles with sufficient force (2000
psi) to
pene-
trate
the
skin.
When
testing,
keep your
person clear
of the
nozzle
spray.
148.
TESTING
AND
LOCATING
FAULTY
NOZZLE.
If the
engine does
not run properly and the quick checks
in paragraph 147 point to a faulty
injection nozzle, locate the faulty
nozzle as follows:
If one engine cylinder is misfiring,
it is reasonable to suspect a faulty
nozzle. Generally, a faulty nozzle can
be located by loosening the high pres-
sure line fitting on each nozzle holder
in turn, thereby allowing fuel to es-
cape at the union rather than enter
the cylinder. As in checking spark
plugs in a spark ignition engine, the
faulty nozzle is the one which, when
its line is loosened, least affects the
running of the engine .
148A, Remove the suspected nozzle
from the engine as outlined in para-
graph 149. If a suitable nozzle tester
is available, check the nozzle, as in
paragraph 148B, 148C, 148D and 148E.
If a nozzle tester is not available, re-
connect the fuel line and with the
nozzle tip directed where it will do no
harm, crank the engine with the start-
ing motor and observe the nozzle
spray pattern as shown in Fig. 61A,
If the spray pattern is ragged, as
shown in the left hand view, the noz-
zle valve is not seating properly and
same should be reconditioned as out-
lined in paragraph 149A. If cleaning
and/or nozzle and tip renewal does
not restore the unit and a nozzle
tester is not available for further
checking, send the complete nozzle
and holder assembly to an official
diesel service station for overhaul,
148B.
NOZZLE TESTER. A complete
job of testing and adjusting the noz-
zle requires the use of a special tester
such as the American Bosch Nozzle
Tester TSE 7722D which is available
through any of the Bosch authorized
service agencies, etc. The nozzle should
Paragraphs 147B-148E
be tested for leakage, spray pattern
and opening pressure. Operate the
tester lever until oil flows and attach
the nozzle and holder assembly.
Note: Only clean, approved testing
oil should be used in the tester tank.
Close the tester valve and apply a
few quick strokes to the lever. If un-
due pressure is required to operate
the lever, the nozzle valve is plugged
and same should be serviced as in
paragraph 149A.
148C.
LEAKAGE. The nozzle valve
should not leak at a pressure less than
1700 psi. To check for leakage, actuate
the tester handle slowly and as the
gage needle approaches 1700 psi, ob-
serve the nozzle tip for drops of fuel.
If drops of fuel collect at pressures
less than 1700 psi, the nozzle valve is
not seating properly and same should
be serviced as in paragraph 149A.
148D.
SPRAY PATTERN. Operate
the tester handle at approximately 100
strokes per minute and observe the
spray pattern as shown in Fig. AC61A.
If the nozzle has a ragged spray pat-
tern as shown in the left view, the
nozzle valve should be serviced as in
paragraph 149 A,
148E.
OPENING PRESSURE. While
operating the tester handle, observe
the gage pressure at which the spray
occurs. The gage pressure should be
2000 psi. If the pressure is not as
specified, remove the nozzle protect-
ing cap, exposing the pressure adjust-
ing screw and locknut. Loosen the
locknut and turn the adjusting screw
as shown in Fig. AC61B either way
as required to obtain an opening pres-
sure of 2000 psi. Note: If a new pres-
sure spring has been installed in the
nozzle holder, adjust the opening pres-
sure to 2020 psi. Tighten the locknut
and install the protecting cap when
adjustment is complete.
Fig.
AC61 — Fuel fiiters and modet PSB
Boseh tn|ection pump Instollatron.
C. Transfer pump F. Secondary (or final)
E.
Intermediate
filter
stage filter
Fig.
AC6TA—Typical spray patterns of a
throttling type pintle nosle. Left: Poor
Spray pattern. Right: ideal spray pattern.
Fig.
AC61B — Ad|usting nonle opening
pressure, using a nozile tester.
30. Nut 32.
Screw driver
31.
Adjusting screw
33.
Nozzle tester
43
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