DETROIT DIESEL 53
Following a complete overhaul or any major repair job
DYNAMOMETER TEST AND RUN-IN
cylinder liners or bearings, the engine should be "run-
in" on a dynamometer prior to release for service.
The Basic Engine
The dynamometer is a device for applying specific
The great number of engine applications make any
loads to an engine. It permits the serviceman to
attempt to establish comparisons for each individual
physically and visually inspect and check the engine
model impractical. For this reason, each model has a
while it is operating. It is an excellent method of
basic engine rating for comparison purposes.
detecting improper tune-up, misfiring injectors, low
compression and other malfunctions, and may save an
A basic engine includes only those items actually
engine from damage at a later date.
required to run the engine. The addition of any engine
driven accessories will result in a brake horsepower
The operating temperature within the engine affects
figure less than the values shown in the Basic Engine
the operating clearances between the various moving
Run-In Schedule. The following items are included on
parts of the engine and determines to a degree how
the basic engine: blower, fuel pump, fresh water pump
the parts will wear. Normal coolant temperature (160o
and governor. The fan and battery-charging generator
- 185°F.) should be maintained throughout the run-in.
typify accessories not considered on the basic engine.
The rate of water circulation through the engine on a
dynamometer should be sufficient to avoid having the
In situations where other than basic engine equipment
engine outlet water temperature more than 10°F.
is used during the test, proper record of this fact
higher than the water inlet temperature. Though a 10o
should be made on the Engine Test Report. The effects
rise across an engine is recommended, it has been
of this additional equipment on engine performance
found that a 15o temperature rise maximum can be
should then be considered when evaluating test results.
Thermostats are used in the engine to control the
coolant flow; therefore, be sure they are in place and
The function of the dynamometer is to absorb and
fully operative or the engine will overheat during the
measure the engine output. Its basic components are a
run-in. However, if the dynamometer has a water
frame, engine mounts, the absorption unit, a heat
stand-pipe with a temperature control regulator, such
exchanger, and a torque loading and measuring
as a Taylor valve or equivalent, the engine should be
tested without thermostats.
The Basic Run-In Horsepower Schedule is shown in the
The engine is connected through a universal coupling
Table. The horsepower shown in the table is at SAE
to the absorption unit. The load on the engine may be
conditions: dry air density .0705 lb/cu. ft., air
varied from zero to maximum by decreasing or
temperature of 85oF., and 500 ft. elevation.
increasing the resistance in the unit. The amount of
BASIC RUN-IN HORSEPOWER SCHEDULE*
Final run-in (within 5% of Rated BHP) should be far 1 1/2 hours at
2800 rpm for all other 4-Valve) cylinder
N45 Injectors Only
October, 1970 SEC. 13.2.1 Page 1