TM 5-3895-359-14&P
ENGINE RUN-IN INSTRUCTIONS
A basic engine includes only those items actually
required to run the engine. The addition of any engine
Following a complete overhaul or any major repair job
driven accessories will result in a brake horsepower
involving the installation of piston rings, pistons, cylinder
figure less than the values shown in the Basic Engine
liners or bearings, the engine should be "Run-In" on a
Run-In Schedule. The following items are included on
dynamometer prior to release for service.
the basic engine: blower, fuel pump, water pump and
governor. The fan and battery-charging generator typify
The dynamometer is a device for applying specific loads
accessories not considered on the basic engine.
to an engine. It permits the serviceman to physically
and visually inspect and check the engine while it is
operating. It is an excellent method of detecting
improper tune-up, misfiring injectors, low compression
and other malfunctions, and may save an engine from
damage at a later date.
The operating temperature within the engine affects the
BASIC ENGINE RUN-IN SCHEDULE
operating clearances between the various moving parts
Speed
Time
of the engine and determines to a degree how the parts
(rpm)
(minutes)
Horsepower
will wear. Normal coolant temperature (160-185 or
F
1200
10
28
71-85 ) should be maintained throughout the Run-In.
C
1800
30
90
*1800
30
110
The rate of water circulation through the engine on a
*2100
30
118
dynamometer should be sufficient to avoid having the
*2300
30
128
engine outlet water temperature more than 100 higher
than the water inlet temperature. Though a 10 rise
*Run at only one of the speeds shown, whichever is at
across an engine is recommended, it has been found
or nearest to the governed speed and reset governor
that a 15 temperature rise maximum can be
after final run, if necessary.
permitted.
A thermostat is used in the engine to control the coolant
flow. Therefore, be sure it is in place and fully operative
or the engine will overheat during the Run-In. However,
if the dynamometer has a water standpipe with a
temperature control regulator, such as a Taylor valve or
equivalent, the engine should be tested without the
thermostat.
The Basic Engine Run-In Schedule is shown in Table 1.
FINAL ENGINE RUN-IN SCHEDULE
The horsepower shown is at SAE conditions: dry air
density .0705 lb/cu. ft. (1.129 Kg/m3), air temperature
Speed
Time
of 85 (29.4 ), and 500 ft. (152 m) elevation.
F
C
(rpm)
(minutes)
Horsepower
DYNAMOMETER TEST AND RUN-IN PROCEDURES
1200
10 (minimum)
28
2100
30
116
The Basic Engine
2100
30
130
2100
30
+
The great number of engine applications make any
+Within + 5% of rated bhp.
attempt to establish comparisons for each individual
model impractical. For this reason, each model has a
TABLE 1
basic engine rating for comparison purposes.
10-9-2
