TM 5-3810-300-24&P-3
13.2.1
ENGINE RUN-IN INSTRUCTIONS
Following a complete overhaul or any major repair job
A basic engine includes only those items actually
involving the installation of piston rings, pistons, cylinder
required to run the engine. The addition of any engine
liners or bearings, the engine should be "Run-in" on a
driven accessories will result in a brake horsepower
dynamometer prior to release for service.
figure less than the values shown in the Basic Engine
Run-In Schedule. The following items are included on
The dynamometer is a device for applying specific loads
the basic engine: blower, fuel pump, water pump and
to an engine. It permits the serviceman to physically and
governor. The fan and battery-charging alternator typify
visually inspect and check the engine while it is
accessories not considered on the basic engine.
operating.
It is an excellent method of detecting
improper tune-up, misfiring injectors, low compression
BASIC ENGINE RUN-IN SCHEDULE
and other malfunctions, and may save an engine from
damage at a later date.
The operating temperature within the engine affects the
operating clearances between the various moving parts
of the engine and determines to a degree how the parts
will wear. Normal coolant temperature (160-185 F or
71-85 C) should be maintained throughout the Run-in.
The rate of water circulation through the engine on a
dynamometer should be sufficient to avoid having the
engine outlet water temperature more than 10 higher
than the water inlet temperature. Though a 10 rise
across an engine is recommended, it has been found
that a 15 temperature rise maximum can be 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.
FINAL ENGINE RUN-IN SCHEDULE
The Basic Engine Run-In Schedule is shown in Table I.
(Cross-Head Pistions)
The horsepower shown is at SAE conditions: dry air
density .0705 lb/cu. ft. (1.129 Kg/m 3, air temperature of
85F (29.4C), and 500 ft. (152 m) elevation.
DYNAMOMETER TEST AND RUN-IN
PROCEDURES
The Basic Engine
The great number of engine applications make any
attempt to establish comparisons for each individual
TABLE 1
model impractical. For this reason, each model has a
basic engine rating for comparison purposes.
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