DETROIT DIESEL 53
13.2.1
ENGINE RUN-IN INSTRUCTIONS
Following a complete overhaul or any major repair job involving the installation of piston rings, pistons, cylinder liners or
bearings, the engine should be "run-in" on a dynamometer prior to release for service.
The dynamometer is a device for applying specific loads 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 operating clearances between the various moving parts of the
engine and determines to a degree how the parts will wear. Normal coolant temperature (160 - 185F.) 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 10F 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.
Thermostats are used in the engine to control the coolant flow; therefore, be sure they are in place and fully operative or
the engine will overheat during the run-in. However, if the dynamometer has a water stand-pipe with a temperature
control regulator, such as a Taylor valve or equivalent, the engine should be tested without thermostats.
The Basic Run-In Horsepower Schedule is shown in the Table. The horsepower shown in the table is at SAE conditions:
dry air density .0705 lb/cu. ft., air temperature of 85F., and 500 ft. 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 model
impractical. For this reason, each model has a basic engine rating for comparison purposes. A basic engine includes
only those items actually required to run the engine. The addition of any engine driven accessories will result in a brake
horsepower figure less than the values shown in the Basic Engine Run-In Schedule. The following items are included on
the basic engine: blower, fuel pump, fresh water pump and governor. The fan and battery-charging generator typify
accessories not considered on the basic engine.
In situations where other than basic engine equipment is used during the test, proper record of this fact should be made
on the Engine Test Report. The effects of this additional equipment on engine performance should then be considered
when evaluating test results.
Dynamometer
The function of the dynamometer is to absorb and measure the engine output. Its basic components are a frame, engine
mounts, the absorption unit, a heat exchanger, and a torque loading and measuring device.
The engine is connected through a universal coupling to the absorption unit. The load on the engine may be varied from
zero to' maximum by decreasing or increasing the resistance in the unit. The amount of
BASIC RUN-IN HORSEPOWER SCHEDULE*
RPM
Time
4-Valve Head
3-53
1800
10 Min.
15
2200
1/2 Hr.
64
Final run-in (within 5% of Rated 8HP) should be for 1 1/2 hours at 2800 rpm for all other 4-Valve) cylinder
head engines.
N45 Injectors Only
October, 1970 SEC. 13.2.1 Page 1
