Operation; Suggested Warm-Up Time; Idle Speed; Extended Idling Periods - Navistar MaxxForce 7 Operation And Maintenance Manual

Operation

SUGGESTED WARM-UP TIME

NOTE: The warm up period allows lubricating oil to establish a
film between moving parts. Keep the engine lower than 1800
rpms and below half throttle for the first 5 minutes.
Cold ambient engine warm-up time can be reduced by operating
the engine under load at reduced engine speed. Begin normal
operation when engine systems reach operating temperature.
The Cold Ambient Protection (CAP) system aids in engine
warm-up and maintains engine heat during extended idling
periods. For further information see Extended Idling Periods
(page 54).

IDLE SPEED

WARNING: To prevent personal injury or death,
provide ventilation when operating an engine in a closed
area. Inhalation of exhaust gas can be fatal.
Low idle speed for the MaxxForce
rpm (nonadjustable). If the engine coolant temperature is below
167°F (75°C) and CAP is enabled, the Engine Control Module
(ECM) adjusts the low idle speed from 700 rpm to a maximum of
1400 rpm. High idle speed (2950 rpm) is a nonadjustable factory
setting.
Page 54
SECTION 4 – ENGINE OPERATION
®
7 Diesel Engines is 700

EXTENDED IDLING PERIODS

CAUTION: To prevent engine damage, do not extend low idle
periods.
Extended idling periods should be avoided.
efficiency is improved when the cylinder temperature remains
high. Low temperature in cylinders may cause the following:
• Unburned fuel may seep from exhaust manifold gaskets and
vehicle exhaust system connections. This seepage has the
dark colored appearance of lubricating oil.
• Incomplete combustion and unburned fuel will wash
lubricating oil from cylinder sleeves. Unburned fuel will be
carried into the lubricating oil, dilute the oil, and change oil
viscosity.
• Carbon will form on internal components of turbocharger
and Exhaust Gas Recirculation (EGR), reducing engine
efficiency.
• Carbon will clog and damage the Diesel Particulate Filter
(DPF).
Diesel engine