TRUCK SERVICE MANUAL
ENGINE
b. Turbocharged engines: Operate 30 minutes extra at
c. Operate with a power requirement low enough to
96 to 100% rated load and rpm. If there is no rapid
allow acceleration to governed speed under any
change in excess of 2 inches [50.8 mm] of water and
condition.
reading does not exceed 100% of representative
pressure, blowby is acceptable.
6. Check exhaust restrictions (back pressure)
as follows:
Note: Manometer readings not exceeding 0.3 inch [7.62
a. Using a mercury or water manometer, take
mm] surge are desirable.
readings when engine is developing maximum
horsepower at maximum engine speed.
CHASSIS DYNAMOMETER TESTS
b. Maximum permissible back pressures are:
If the engine is installed In equipment, it may be tested
on a chassis dynamometer as follows:
All Models
(1) 3.0 inch [76 mm] Hg. or 20 inches [508 mm] of water
1.
Check instruments, follow manufacturer's
for all naturally aspirated engines.
instructions.
2. Perform all phases of engine dynamometer BreakIn
(2) 3.0 inch [76 mm] Hg. or 25 inches [635 mm] of water
Run. See Table 1414.
for all turbocharged engines.
Maintenance Of Dynamometer
7. Check smoke level,
Follow manufacturer's maintenance
instructions
to
service dynamometer.
ANEROID CONTROL ADJUSTMENT
Calibrating Instruments
The aneroid bellows spring is preset and sealed at
Keep beam or spring scales properly calibrated. Follow
Cummins Engine Company, Inc.
The following
manufacturer's recommendation when recalibrating or
adjustment can be made while the engine is on a
instrument adjustment is necessary.
dynamometer.
1. Start engine and check idle speed. In most
In-Chassis Run-In
cases, idle will be low and must be adjusted upward with
Inchassis repaired engines should receive runin
fuel pump governor idle screw.
equivalent to that on an engine dynamometer. Follow
2. Check engine rated power and speed. If smoke
procedure given below after an inchassis repair or
is not excessive during first 15 seconds of full throttle
rebuild.
operation, but becomes excessive thereafter, aneroid is
not at fault.
1. Start engine. Idle at 800 to 1000 rpm, noload,
3. Check fuel system and turbocharger before
for 5 to 10 minutes. Check oil pressure and water
readjusting aneroid control.
circulation. Correct any leaks.
4. If hard starting is encountered, the aneroid
2. Operate at 1/4 to 1/2 throttle for first 5 to 10
pressure valve may be sticking in open position, closed
hours.
position will result in excessive smoke. Replace if
3. Operate at 1/2 to 2/3 throttle for next 45 to 50
necessary.
hours.
PAINT ENGINE
4. After 50 hours of operation, do not operate
1. Prior to painting, clean surface for maximum
engine at full load and speed in excess of 5 minutes
paint adherence. Dry with compressed air.
continuously at any time. After 5 minutes full power run,
2. Cover all openings, pulley grooves, instrument
drop back to 3/4 throttle.
faces and belts. Cover all data plates, exposed threads,
5. During the first 100 hours' service:
wire terminals, hose fittings and pipe openings with water
proof paper or tape.
a. Do not idle engine for long periods.
3. Cover clutch contact surface on flywheel with
b. Watch instruments closely. Decrease engine
antirust compound, if engine is not going into immediate
rpm if oil temperature reaches 250 deg. F [121 deg. C]
service.
or if coolant temperature exceeds 190 deg. F [88 deg.
4. Spray outside surfaces of castings and
C] .
corrodible parts with a primer coat of yellow lacquer to
serve as a base for the second coat of engine enamel.
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