2.1.1 Fuel Injector
DETROIT DIESEL 53
pipes from an injector, cover the filter caps
Test Injector
with shipping caps to prevent dirt from
If inspection does not reveal any external damage, then
entering the injector. Also protect the fuel
perform a series of tests to determine the condition of
pipes and fuel connectors from entry of dirt
the injector to avoid unnecessary overhauling.
or foreign material.
An injector that passes all of the tests outlined below
3.
Crank the engine to bring the outer ends of the
may be considered to be satisfactory for service without
push rods of the injector and valve rocker arms in line
disassembly, except for the visual check of the plunger.
horizontally.
However, an injector that fails to pass one or more of
4.
Remove the two rocker shaft bracket bolts and
the tests is unsatisfactory. Perform all of the tests
swing the rocker arms away from the injector and valves
before disassembling an injector to correct any one
(Fig. 7).
condition.
5.
Remove the injector clamp bolt, special washer
Identify each injector and record the pressure drop and
and clamp.
fuel output as indicated by the following tests:
6.
Loosen the inner and outer adjusting screws on
INJECTOR CONTROL
RACK
AND
PLUNGER
the injector rack control lever and slide the lever away
MOVEMENT TEST
from the injector.
Place the injector in the injector fixture and rack
7.
Lift the injector from its seat in the cylinder head
freeness tester J 22396. Refer to Fig. 8. and place the
(Fig. 7.).
handle on top of the injector follower.
8.
Cover the injector hole in the cylinder head to
If necessary, adjust the contact screw in the handle to
keep foreign material out.
ensure the contact screw is at the center of the follower
when the follower spring is compressed.
9.
Clean the exterior of the injector with clean fuel
oil and dry it with compressed air.
Fig. 12. - Unusable Plungers
Fig. 13.- Installing Injector Valve Parts on Auxiliary
Tester J 22640
1972 General Motors Corp.
Page 6
