DETROIT DIESEL 53
ENGINE RUN-IN INSTRUCTIONS
Following a complete overhaul or any major repair job
DYNAMOMETER TEST AND RUN-IN
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 Basic Engine
The dynamometer is a device for applying specific loads
A basic engine includes only those items actually
to an engine. It permits the serviceman to physically
required to run the engine. The addition of any engine
and ,visually inspect and check the engine while it is
driven accessories will result in a brake horsepower
operating. It is an excellent method of detecting
figure less than the values shown in the Basic Engine
improper tune-up, misfiring injectors, low compression
Run-In Schedule. The following items are includes on
and other malfunctions, and may save an engine from
the basic engine: blower, fuel pump, fresh water pump
damage at a later date.
and governor. The fan and battery-charging generator
typify accessories not considered on the basic engine.
The operating temperature within the engine affects the
operating clearances between the various moving parts
In situations where other than basic engine equipment is
of the engine and determines to a degree how the parts
used during the test, proper record of this fact should be
will wear. Normal coolant temperature (160 - 185F.)
made on the Engine Test Report. The effects of this
should be maintained throughout the run-in.
additional equipment on engine performance should
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
The function of the dynamometer is to absorb and
across an engine is recommended, it has been found
measure the engine output. Its basic components are a
that a 15 temperature rise maximum can be permitted.
frame, engine mounts, the absorption unit, a heat
exchanger, and a torque loading and measuring device.
Thermostats are used in the engine to control the
coolant flow; therefore, be sure they are in place and
The engine is connected through a universal coupling to
fully operative or the engine will overheat during the run-
the absorption unit. The load on the engine may be
in. However, if the dynamometer has a water stand-
varied from zero to maximum by decreasing or
pipe with a temperature control regulator, such as a
increasing the resistance in the unit. The amount of
Taylor valve or equivalent, the engine should be tested
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.
temperature of 85F., and 500 ft. elevation.
Final run-in should be for 1/2 hr. at 2800 RPM within 5% of 210 B.H.P.
1970 General Motors Corp.
SEC. 13.2.1 Page 1