Mack ASET AC, Service Manual, Page: 478 / 536

REPAIR INSTRUCTIONS, PART 3
Page 465
Engine Operational Check
1. Remove all tools from the engine
compartment.
2. Connect the battery cables (negative cable
last).
3. Clear the work area of debris and personnel.
The following step is important to ensure
adequate break-in for all new parts — camshaft,
lifters, crankshaft, bearings, etc. — at initial
startup of the engine.
4. Start the engine and immediately increase
the speed to 1200 rpm. Operate the engine
in the range of 1200–1600 rpm for
15 minutes. DO NOT allow the engine to
drop to idle speed until the 15 minute
break-in period at 1200–1600 rpm has been
completed. During the break-in period,
check for leaks and monitor gauges for
satisfactory oil pressure, etc.
5. After the break-in is complete, shut down the
engine. Check the fluid levels and fill to
capacity before restarting the engine.
6. Refer to the “Rebuilt Engine Run-In
Procedures” for checks to ensure proper
engine operation before releasing the
vehicle for service.
REBUILT ENGINE RUN-IN
PROCEDURES
General Instructions
The durability and service life of a rebuilt engine
is directly related to its initial run-in following
overhaul. After a complete overhaul or any major
repair job involving installation of piston rings,
pistons, cylinder sleeves or bearings, the engine
must be run-in prior to release for service.
Run-in procedures vary depending on method
used (i.e., engine dynamometer, chassis
dynamometer or highway run-in). Regardless of
method, however, always properly prepare the
engine before starting it for the first time.
Run-In Check
Install any additional instrumentation needed for
the run-in method selected.
The operator should be familiar with the correct,
established procedure for checking chassis
power
before using the chassis dynamometer
method for run-in (refer to applicable chassis
dynamometer operation procedures).
The operator must be observant throughout the
entire run-in procedure, in order to detect any
problems that develop. Constantly monitor the
instrumentation displaying functions of the engine
and support systems, and record all readings.
If, during run-in, the engine develops any of the
following abnormal running characteristics, shut it
down immediately. Investigate and correct the
problem before continuing the run-in procedure.
Always investigate the following conditions:
앫
Unusual noises such as knocking, scraping,
etc.
앫
A significant drop in engine oil pressure
앫
A significant rise in coolant temperature,
exceeding 240
°
F (116
°
C)
앫
A significant rise in oil temperature that
exceeds 240
°
F (116
°
C)
앫
An exhaust temperature that exceeds
maximum acceptable limits for the specific
engine involved, as measured by a
pyrometer (if vehicle is equipped with a
pyrometer)
앫
Any oil, coolant or air inlet system leaks
CYLINDER HEAD RETORQUING
After completing the run-in procedure, in
sequence, back off each cylinder head capscrew
individually until free. Then retorque the same
capscrew to 205 lb-ft (278 N
폷
m).
5-111.bk Page 465 Monday, July 10, 2006 2:26 PM