Onan DJA Series User Manual

Never use hard or sharp tools, emery paper, grinding
powder or abrasives of any kind.
Soak each nozzle in fuel to loosen dirt. Then clean the
inside with a small strip of wood soaked in oil and the
spray hole with a wood splinter. If necessary, clean the
outer surfaces of the nozzle body with a brass brush but
do not attempt to scrape carbon from the nozzle sur-
faces. This can severely damage the spray hole. Use a
soft oil-soaked rag or mutton tallow and felt to clean
the nozzle valve.
Repair: If cleaning will not eliminate a nozzle defect,
replace the nozzle or take it to an authorized service
station. Do not attempt to replace nozzle parts except
for the nozzle and pintle assembly.
Assembly: Rinse both the valve and nozzle thoroughly
before assembly and coat with oil. The valve must be
free in the nozzle. Lift it about 1/3 way out of the
body. It should slide back to its seat without aid when
the assembly is held at a 45° angle. If necessary, work
the valve into its body with clean mutton tallow.
1. Remove all pressure on the nozzle spring by
adjusting the pressure adjusting screw.
2. Clamp the nozzle holder body in a vise.
3. Set the valve in the body and set the nozzle over
it.
4. Install the nozzle cap nut loosely.
5. Place the centering sleeve over the nozzle (Figure
17) for initial tightening. Then remove the center-
ing sleeve to prevent it from binding between
nozzle and cap nut and tighten the nozzle cap nut
to specified torque.
NOZZLE
CENTERING
SLEEVE
FIGURE 17. TIGHTENING NOZZLE CAP NUT
Installation: Before installing the injection nozzle in
the engine, thoroughly clean the mounting recess.
A dirty mounting surface could permit blow-by, causing
nozzle failure and a resulting power loss.
1. Install a new heat shield to head gasket in the
cylinder head recess.
2. Install the heat shield, a new nozzle gasket and
the nozzle adapter.
3. Insert the nozzle assembly into the recess. Do not
strike the tip against any hard surface.
4. Install the nozzle flange and two cap screws.
Tighten the cap screws alternately to avoid cock-
ing the nozzle assembly. Tighten each cap screw
to 20-21 foot-pounds.
PREHEATING CIRCUIT
This circuit consists of a manifold heater to heat the
engine intake air in the intake manifold and a glow
plug to heat the precombustion chamber. Used for
engine starting, the manifold heater and glow plug are
wired in parallel and controlled by a preheat switch.
Check the heater by removing its lead, operating the
preheat switch, and touching the lead to its terminal.
If it sparks, there is continuity and the heater is work-
ing. If any components of this circuit fail, replace them.
Do not attempt repairs on individual components. If
there is still a question, check the component for
heating.
DECOMPRESSION RELEASE
Before adjusting the decompression release, valves
must be set for correct clearance. After checking valve
clearance, leave the flywheel at 10° to 45
0
ATC with
piston on power stroke so the exhaust valve will have
its maximum clearance when adjusting the decompres-
sion release. See Figure 18.
Set the arm in the decompression position (tension
against release spring). Turn the setscrew so the end
just touches the exhaust rocker arm. Be sure the de-
compression release arm is up right against the lock
ring. Then turn the screw exactly one revolution clock-
wise.
NOTE: // the screw is tightened more than one turn,
the exhaust valve could hit the piston.
Hold the setscrew and tighten the lock nut 1/4 to 1/2
turn past finger tightness.
Release the mechanism to allow compression. Check
the clearance between the screw and rocker arm. Take
up valve clearance by inserting a feeler gauge between
the valve and rocker arm. If the setscrew does not
clear the rocker arm, loosen the lock nut and back off
the screw until clearance is obtained.
19

Onan DJA Series Specifications

General

Brand	Onan
Model	DJA Series
Category	Engine
Language	English