49
Injectors
The job of the injectors is to atomize and spray the
fuel, metered precisely by the injection pump, into
the engine’s combustion chambers. This injection
takes place under extremely high pressure so that at-
omization and combustion of the fuel takes place as
effectively as possible.
Each injector basically comprises a nozzle holder
and a nozzle (jet). When the fuel pressure increases
to a set value (opening pressure), the nozzle needle
(7), which is pressed in its seat by the thrust spring
(4), is raised, and atomized fuel is sprayed into the
engine through carefully calibrated holes in the noz-
zle body. The tension of the thrust spring determines
the opening pressure of the injector.
The injectors should be checked regularly by author-
ized personnel, refer to maintenance schedule. An
incorrect opening pressure or faulty nozzle will result
in smoky exhaust gases and lower engine output.
Maintenance – Fuel System
Checking/draining fuel pre-filters
Check the fuel filter and drain off any water and con-
taminants through the drain plug(s) (5). See illustra-
tion on next page.
The engine should be off and allowed to stand for a
few hours before carrying out this check. Reinstall
the plugs.
Fuel pre-filter. Installing new inserts
Double filter: As a rule, the filter inserts should be
replaced when the pressure gauge indicates a vacu-
um of 6–10 in. Hg* (idle) or 16–20 in Hg respectively,
(max. rpm, loaded engine). However, filters must be
replaced every 500 hours of use.
Close the fuel cocks at the tank before dismantling
the single filter or replacing the inserts of the double
filter with the engine off.
Double filter: If inserts are to be replaced when the
engine is running, shut off the filter unit with the insert
to be replaced by turning the valve handle (1) to the
horizontal position. See illustration on next page.
*Note: In. Hg = Inches of mercury.
Positions of the valve knob
Up: Normal operating position. Both filters on
line.
Right: Left side filter insert can be replaced.
Left: Right side filter insert can be replaced.
Down: Both filters are off line.
1. Place a container beneath the fuel filters. Re-
move the cover (4) and lift out the insert by rotat-
ing it. See illustration on next page.
2. Drain off any water or contaminants through the
drain plug (5).
3. Install new filter insert and fill container with clean
diesel oil. Fit the cover with a new gasket and
tighten it by hand.
Note! Moisten the gasket with diesel oil before
installation. Cleanliness! The fuel in the system
must not become contaminated.
4. Double filter: Replace the other filter insert in
the same way.
5. Dry off any diesel fuel spilt on the heat shield.
6. Double filter: Both filter units on-line (turn the
knob (5) up to the vertical position).
7. Open the fuel cocks and check that there are no
leaks.
Injectors
1. Pressure line connection
2. Connection for fuel leak-off pipe
3. Shims for setting the opening pres-
sure
4. Thrust spring
5. Thrust pin
6. Jet
7. Nozzle needle
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