REPAIR INSTRUCTIONS, PART 2
Page 269
Cleaning and Inspection
Since the unit injectors operate at very high fuel
injection pressures, the nozzle tip spray holes
and the immediate area around the spray holes
remain clean and free of carbon deposits. This
leaves the cap nut seat surface as the only
surface which requires a thorough cleaning.
Clean the injector cap nut surface as follows:
1. Remove the two O-rings from the injector
and discard the O-rings.
2. Cover the O-ring grooves and the complete
area between the grooves with tape or
equivalent to prevent contaminants from
getting into the injector.
3. Cover the opening for the electrical
connection.
4. Slide a short section of 6 mm (0.25 inch) ID
hose over the injector nozzle tip until it
covers approximately half the nozzle tip
length. This is necessary to protect the
nozzle spray holes from damage when
cleaning the cap nut seat surface.
390
Figure 390 — Injector Nozzle Tip Cover
5. With the unit injector nozzle tip spray holes
protected, carefully clean the cap nut seat
surface of hard carbon deposits using a wire
wheel. Apply only light nominal pressure to
hold the wire wheel against the injector
surface for short periods of time.
391
Figure 391 — Cleaning Injector Cap Nut Seat Surface
The carbon will be very hard and difficult to
remove. Avoid the tendency to use excessive
pressure in holding the wire wheel against the
injector cap nut surface. Excessive force can
damage the cap nut surface, making the injector
unacceptable for reuse.
6. Clean any remaining carbon using hand
tools such as a hand scraper or medium grit
emery cloth.
7. After cleaning, inspect the injector nozzle
cap nut seat surface for pitting or related
damage. If there is pitting or other damage,
replace the injector.
Pitting on surfaces other than the cap nut seat
does not affect the function of the unit injector and
is acceptable.
8. Install new O-rings in the grooves on the
injector along with a new sealing washer on
the injector.
9. Lubricate the injector O-rings with clean
engine oil.
Final Steps
Install the following components on the engine
(see ENGINE REASSEMBLY for procedures):
앫 Unit Injectors
앫 Rocker Arm Shaft Assembly
앫 Cylinder Head Cover
1. Injector Cap Nut Seat
Surface
2. Hose (covering Nozzle
Tip)
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