Whenever an injector is replaced, nuts should be left slack until all the air bubbles are out of the pipeline
and pure fuel is flowing.
When testing nozzles, be sure the spray is directed away from the engine because oil must not be
sprayed into the combustion chambers. Also, if the spray strikes the hands or face, it will penetrate the
skin. Tighten the following parts and check them for fuel leakage: holding nut, spring guide holding nut
and locknut, fuel lead-off stud, and the nuts holding the injection and overflow pipes to the holder.
Some parts of a nozzle are shown in the cut-away sketch, in figure 2.5.
When fuel pipes are installed, they should not be sprung to catch the nut. If pipes do not line up
with their connections, they must be bent slightly; clamp the pipes to prevent any vibration. If a nozzle
valve sticks, smoky exhaust and engine pounding will occur; locate the defective nozzle by cutting out
cylinders in rotation. Opening pressure of injection nozzles can be checked by a testing device that uses
a spare pump to develop the injection pressure as follows:
Attach spare pump to the injection tube on the test rack. Set the fuel pump rack at 20-mm travel.
Test the nozzle by pumping the lever steadily until fuel discharges, and note the pressure indicated on
the gage. The maximum pressure noted on the gage at each stroke is the opening pressure of the nozzle.
Do not operate the lever quickly as this will cause extremely high pressure to build up, giving an
unreliable gage reading. Turn the pressure adjusting screw on top of the nozzle holder until the
manufacturer's pressure specifications are met. After setting the pressure of the nozzle, set the fuel
pump rack at the limit of its travel and operate the test rig to see if the nozzle operates properly.
If oil is changed and filters are replaced according to appropriate lubrication orders or
maintenance instructions, it isn't necessary to flush the lubricating system. It may be necessary to flush
the system, however, when replacing detergent oil with another brand of detergent oil or when replacing
mineral oil with a detergent oil. It is necessary to drain and flush the system when metal particles or
water are in the oil or when the engine is dirty even after a detergent oil has been used. Flushing oil may
be either the regular OE used in the crankcase, if used at a temperature of 150F. to 200 F., or the OE
10 light grade oil. When using the light OE 10