DETROIT DIESEL 53
Fuel lnjector
2.1.1
Fig. 43 - Relationship Between Exhaust Valve Bridge and Valve Stems
ASSEMBLE PLUNGER AND FOLLOWER
a former injector if a new design spray tip
assembly is used.
1. Refer to Fig. 37 and slide the head of the plunger
into the follower.
5. Place the spring cage, spring seat and valve spring
assembly (valve spring down) on top of the check
2. Invert the injector in the assembly fixture (filter cap
valve cage.
end up) and push the rack all the way in. Then place
the follower spring on the Injector body.
CAUTION: When installing a new spray tip
assembly in a former injector, a new valve
3. Refer to Fig. 41 and place the stop pin on the
spring seat must also be installed. The current
injector body so that the follower spring rests on the
needle valve has a shorter quill.
narrow flange of the stop pin. Then align the slot in
the follower with the stop pin hole in the injector
body. Next align the flat side of the plunger with the
6. Insert the needle valve. tapered end down, inside of
slot in the follower. Then insert the free end of the
the spray tip (Fig. 2). Then place the spray tip and
plunger in the injector body. Press down on the
needle valve on top of the spring cage with the quill
follower and at the same time press the stop pin into
end of the needle valve in the hole in the spring cage.
position. When in place, the spring will hold the stop
pin in position.
7. Lubricate the threads in the injector nut and
carefully thread the nut on the injector body by hand.
Rotate the spray tip between your thumb and first
Check Spray Tip Concentricity
finger while threading the nut on the injector body
(Fig. 39) Tighten the nut as tight as possible by hand.
To assure correct alignment, check the concentricity of
the spray tip as follows:
At this point there should be sufficient force on the
spray up to make it impossible to turn with your
1. Place the injector in the concentricity gage J 5119 as
lingers.
shown in Fig. 42 and adjust the dial indicator to zero.
8. Use socket J 4983-01 and a torque wrench to tighten
and note the total run-out
2. Rotate the injector 360
the injector nut to 75-85 lb-ft torque (Fig. 40).
as indicated on the dial.
NOTE: Do not exceed the specified torque.
3. If the total run-out exceeds .008 " , remove the
Otherwise, the nut may be stretched and result
injector from the gage. Loosen the injector nut, center
in improper sealing of the lapped surfaces in a
the spray tip and tighten the nut to 75-85 lb-ft. torque.
Recheck the spray tip concentricity. If, after several
subsequent injector overhaul.
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