Service Manual User Manual

Section 8B
8B-14
To test a fuel injector:
1. Remove the fuel injector from the cylinder head.
2. Invert the fuel injector with the nozzle facing out, then
retighten the unions.
3. Loosen the unions of the other fuel injector pipes (to
help avoid the possibility of the engine starting).
4. Operate the starter to turn the engine over until fuel
sprays from the nozzle. Examine the shape of the
spray. If the spray is unduly “wet” or “streaky”, or
obviously sprays to one side, or if the nozzle
“dribbles” fuel, it may only be necessary to probe the
nozzle holes to remove blockage.
IMPORTANT: DO NOT attempt to adjust injection pres-
sure without a testing pump and pressure gauge. It is
impossible to accurately adjust the setting of fuel injec-
tors without the proper equipment.
A perfect fuel injector, when tested by pumping fuel
through it in the open air, gives a short “pinging” sound as
the fuel emerges from the holes. After the fuel injector
has been in service for some time, the pinging changes
to a crackling sound. It is not until the fuel injector sounds
“dead” that its condition is likely to affect the running of
the engine.
B. Injector Replacement
Preparatory steps:
• Thoroughly clean around the injector(s)
• Disconnect the high-pressure fuel line(s)
• Disconnect the fuel drain manifold
IMPORTANT: The injector must not rotate in the bore of
the cylinder head or damage to the cylinder head will
occur. If rust has formed on the hold-down nut, soak the
nut with rust-penetrating solvent for a minimum of three
minutes. Then, tap the injector body with a drift pin to
help loosen any rust.
1. Use a 16 mm wrench to prevent the injector body
(Fig. 8B–9) from turning. Loosen the hold-down nut
with a 24 mm box wrench.
Figure 8B–9. Fuel injector.
2. Clean the injector nozzle bore.
3. Remove the injector hold-down nut from the injector
body.
4. Apply a light coat of anti-seize compound to the new
injector surface. Avoid getting anti-seize compound
into the fuel drain hole.
5. Install the hold-down nut on the injector body.
6. Install a new O-ring into the recessed groove in the
top of the hold-down nut. Make sure the O-ring is not
cut or twisted during installation.
7. Apply a light coat of anti-seize compound to the to
the threads of the injector hold-down nut.
8. Assemble the injector and new copper washer. Use
only ONE copper washer. A light coat of clean
15W40 engine oil placed between the washer and
the injector will help keep the washer from falling
during installation.
9. Install the injector with the protrusion on the side of
the nozzle fitting into the notch in the head.
10. Tighten the hold-down nut and torque to 44 lb/ft
(60 Nm).
11. Install the fuel drain manifold and torque to 6 lb/ft
(8 Nm).
12. Install the high-pressure fuel lines and torque to 18
lb/ft (24 Nm).
13. Run the engine and check for fuel and air leakage.
WARNING: KEEP CLEAR of spraying fuel.
Diesel fuel will spray when venting high pres-
sure lines. The fuel pressure is sufficient to
penetrate the skin and cause serious bodily
injury. Wear protective clothing and safety
glasses.
MA1960
Injector body
O-ring
Hold-down nut
Protrusion
Notch
Copper washer
Model 3606 • Origin 10/99