DETROIT DIESEL 53
1. Support the injector. right side up, in holding fixture
2. Compress the follower spring. Then raise the spring
above the stop pin with a screw driver and withdraw
the pin (Fig. 11). Allow the spring to rise gradually.
3. Remove the injector from the holding fixture. Turn
the injector upside down. to prevent the entry of dirt.
and catch the spring and plunger as they drop out.
4. Inspect the plunger. If the plunger is chipped
(Fig. 12). replace the plunger and bushing assembly
5. Reinstall the plunger, follower and spring.
NEEDLE VALVE TEST
Remove the Injector nut and remove all of the parts
below the Injector bushing as outlined under
Clean all of the carbon off of the spray tip seat in the
Injector nut as outlined under Clean Injector Parts.
If the spray pattern test indicated that tip cleaning is
necessary, clean the carbon from the tip cavity below
the needle valve and orifices as outlined under Clean
With the injector nut and spray tip cleaned. assemble
the check valve. check valve cage, spring, spring seat,
spring cage. needle valve and tip assembly on
auxiliary tester J 22640 (Fig. 13). Carefully pilot the
Injector nut over the spray tip and valve parts and
thread it on the body as shown in Fig. 13. Tighten the
injector nut to 75-85 lb-ft torque.
Install the shield in the auxiliary tester as shown in
Fig 14 and operate the pump handle until the spray
tip valve has opened several times to purge the air
from the system.
Operate the pump handle with smooth even strokes
(40 strokes per minute) and note the pressure at which
the needle valve opens. The valve should open between
2300 and 3300 psi. The opening and closing action
should he sharp and producer a fineIy atomized spray.
If the valve opening pressure is below 2300 psi and/or
SEC. 2.1.1 Page 9