chevrolet truck Light Duty Truck 1994 Series, Repair Manual

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2. Depress the tester lever slowly. Note at what pres­
sure the needle of the pressure gage stopped. The
maximum observed pressure is the opening pres­
sure.
• Some nozzles may pop while other nozzles
may drip down. This is not leakage.
3. The opening pressure should not fall below the
lower limit of 105 bar (1500 psi) on used nozzles
on 6.5L engines and 120 bar (1750 psi) on 6.5L
turbocharged engines.
4. Replace nozzles which fall below the lower limit.
LEAKAGE TEST
1. Further open the shutoff valve at the pressure gage
(1/2 to 1 1/2 turns).
2. Blow-dry the nozzle tip.
CAUTION: When testing nozzles, do not place
your hands or arms near the top of the noz­
zle. The high pressure atomized fuel spray
from a nozzle has sufficient penetrating pow­
er to puncture flesh and destroy tissue and
may result in blood poisoning. The nozzle tip
should always be enclosed in a receptacle
preferably transparent, to contain the spray.
3. Depress the lever of the manual test stand slowly
until the gage reads a pressure of 95 bar (1400
psi). Observe the nozzle tip. A drop may form on
the end of the nozzle but should not drop off within
a period of 10 seconds.
4. Replace the nozzle assembly if a drop falls during
the 10 seconds.
CHATTER TEST
When testing for chatter, it should be noted that the
sound (chatter) for new and used nozzles may vary.
This is due to carbonized fuel deposits on the pintle
and nozzle tip of used nozzles. With some used noz­
zles, chatter is difficult to detect during slow actuation of
the hand lever.
Some nozzles may chatter louder than others. As
long as there is chatter, the nozzle is acceptable.
1. Close the shutoff lever at the pressure gage.
CAUTION: When testing nozzles, do not place
your hands or arms near the top of the noz­
zle. The high pressure atomized fuel spray
from a nozzle has sufficient penetrating pow­
er to puncture flesh and destroy tissue and
may result in blood poisoning. The nozzle tip
should always be enclosed in a receptacle
preferably transparent, to contain the spray.
2. Depress the lever of the test stand slowly and note
whether chatter noise can be heard.
3. If no chatter is heard, move the lever faster until it
chatters. At fast lever movement, the nozzle may
make a “ hissing” or “squealing” sound rather than
the normal chatter. This is acceptable.
4. These sounds indicate that the nozzle needle
moves freely and that the nozzle seat, guide, and
pintle are OK.
5. Replace nozzles that do not chatter.
SPRAY PATTERN
This nozzle features a longer nozzle overlap, greater
pintle to body clearance, and an internal wave washer
between the nozzle nut and the nozzle. These features
make objective spray pattern testing difficult.
A pop tester will not deliver fuel fast enough for prop­
er spray pattern analysis. Based on this, this type of
nozzle should not be rejected for spray pattern.
Replace any faulty nozzles. Do not attempt repairs.
IN JE C TIO N LIN ES
L1
I9
Inspect
Injection lines for kinks and damaged fittings.
Replace any damaged lines.
IN JE C TIO N PUM P
Inspect
• Injection pump body and mounting flange for dam­
age.
• Injection pump for evidence of fuel leakage.
• Injection line fittings for stripping.
INJECTION PUMP REPAIR
Refer to the SECTION 6C2 in the proper service
manual for allowable repairs. If necessary, have the
pump repaired by an authorized repair station.
CRANKSHAFT AND BEARINGS
CLEANING AND INSPECTION
Clean
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A. Crankshaft with solvent.
• Do not scratch the bearing journals.
• Blow all sludge from the oil passages with com­
pressed air.
B. Main bearing inserts. Wipe free of oil with a soft
cloth.
17 Inspect
A. Crankshaft for cracks. Use the magnaflux method,
if available.
B. Crankpins, main bearing journals, and thrust sur­
faces for scoring, nicks, or damage caused by lack
of lubrication.
C. Main bearing inserts for scoring or other damage.
In general, the lower inserts (except the #1 bearing)
show greater wear and the most distress from fatigue.
If, upon inspection, the lower insert is suitable for use, it
can be assumed that the upper insert is also satisfacto­
ry. If the lower insert shows evidence of wear or dam­
age, both the upper and lower inserts must be replaced.
Measure (Figures 59 and 60)
A. Main bearing and connecting rod journal diameters
(figure 59). Compare with “ Specifications.” Grind or
replace the crankshaft if necessary.