TRUCK SERVICE MANUAL
3. Naturally aspirated engines must be derated 3%
to assure lowest smoke potential and avoid excessive
for each 1000 ft. [304.8 ml altitude above sea level, and
injector train loads.
1% for each 10 deg. F [6 deg. C] ambient temperature
rise above 60 deg. F [16 deg. C].
4. Turbo-charged engines do not require fuel
1. Run engine at rated speed for 5 minutes. It
derating below maximum altitudes shown in the
should develop 96% of rated horsepower at standard
"Dynamometer Test Chart." Above maximum altitudes,
fuel rate. Check crankcase pressure (blowby). If
derate at 4% for each 1000 ft. [304,8 ml additional
pressure exceeds value shown in Table 1414 reduce
altitude and 1% for each 10 deg. F [6 deg. C] air
engine speed and load to preceding phase; run engine
temperature rise above 12 deg. F [52 deg. C].
30 to 45 minutes.
5. New or newly rebuilt engines during
2. Repeat procedure described above until engine
dynamometer tests are not required to deliver more than
develops 96% rated horsepower at standard fuel rate
96% of maximum horsepower at power checks.
3. After power check is completed, remove pipe
plugs in naturally aspirated engine cylinder heads and
install vent plugs. On turbocharged engines connect
aneroid, if used.
CHECKS DURING RUNING TEST
Start engine and idle at approximately 800 rpm no load
During the period of engine runin, the following checks
for five to ten minutes. Check oil pressure and water
should be made frequently.
circulation; look for leaks.
At Each Phase
1. Lubricating oil pressure should remain at or near
1. Apply dynamometer load to (+10%) horsepower
a constant figure at constant engine speed and load (see
at (+5%) speed shown in Table 1414 "Dynamometer
Table 1415) after normal operating temperature has
been reached. Abnormally high pressures may indicate
2. Check crankcase pressure (blowby) with ST487.
blocked lubricating oil lines. Abnormally low pressures
If pressure continues to drop, reduce run-in time by half;
indicate an insufficient supply of lubricating oil from the
otherwise, run engine for time period shown on
pump or increased oil clearances which may be due to
2. If oil temperature rises sharply above 225 deg.
At Phase 1
F [107 deg. C] shut down engine and correct as
1. Run engine until normal oil operating
temperature has been obtained.
3. New lubricating oil filter elements will absorb oil;
2. Add lubricating oil to bring level up to "H" mark
therefore, engine must be shut down after five or ten
on bayonet gauge, allow oil temperature to stabilize.
minutes of operation and additional oil added to bring oil
level to "H" mark on bayonet oil gauge. Check oil level
At Phase 2
every phase during runin test.
Set engine Idle, governed speed and fuel rate.
At Phase 3
See Service Tool Instructions,
If blow by rises, reduce load to preceding phase and run
for 30 minutes; then return to original phase
After engine is started, add coolant as necessary to
completely fill cooling system and replace entrapped air.
At Phase 4
Coolant should not exceed 200 deg. F [93 deg. C] or
1. Run at speed and horsepower indicated.
drop below 160 deg. F [71 deg. C] during engine
2. Check for leaks and tighten all exposed
operation. Do not turn engine off immediately after a
load run. Heat stored in the iron masses will boil coolant
3. Recheck valves and injectors.
in the jackets if air and coolant circulation is immediately
Setting," refer to Tables 1411, 14.12 and 1413.
stopped while engine is hot. Allow engine to idle for a
few minutes before shutting down.
Note: Readjustment after 1 hour operation is necessary