DETROIT DIESEL 53
Fuel Injector 2.1.1
check for free movement Replace the plunger and
Port
Minimum
Name
Thickness
bushing as an assembly if any of the above damage is
noted, since they are mated parts. USC new mated
.199
Tip, Spray (Shoulder)
factory parts to assure the best performance from the
Cage, Check Valve
.165-.163
injector.
Valve, Check
.022
.602
Cage, Valve Spring
injector plungers cannot be reworked to change the
output. Grinding will destroy the hardened case at the
MINIMUM THICKNESS (Used Parts)
helix and result in chipping and seizure or scoring of
the plunger.
establishing the valve opening pressure of the injector
assembly. Replace a worn or broken spring.
Examine the spray tip seating surface of the injector
nut and spray tip for nicks, burrs, erosion or
Inspect the sealing surfaces of the injector parts
brinelling. Reseat the surface or replace the nut or tip
indicated by arrows in Fig. 31. Examine the sealing
if it is severely damaged.
surfaces with a magnifying glass as shown in Fig. 32
for even the slightest imperfections will prevent the
injector from operating properly. Check for burrs,
The injector valve spring plays an important part in
nicks, erosion, cracks, chipping and excessive wear.
Also check for enlarged orifices in the spray tip.
Replace damaged or excessively worn parts. Check the
minimum thickness of the lapped parts as noted in the
chart.
Examine the seating area of the needle valve for wear
or damage. Also examine the needle quill and its
contact point with the valve spring seat. Replace
damaged or excessively worn parts.
Examine the needle valve seat area in the spray tip for
foreign material. The smallest particle of such
material can prevent the needle valve from seating
properly. Polish the seat area with polishing stick
J 22964. Coat only the tapered end of the stick with
polishing compound J 23038 and insert it directly into
the center of the spray tip until it bottoms. Rotate the
stick 6 to 12 times, applying a light pressure with the
thumb and forefinger
CAUTION: Be sure that no compound is
Fig. 38 - Comparison of Former and New
Fig. 37 lnjector Plunger, Follower and
Design Injector Parts
Relative Location of Parts
SEC. 2.1.1 Page 17
March, 1973
