Shutting Down The Engine - Mack Granite GU Series Operator's Handbook Manual

174 OPERATION

Shutting Down the Engine

Standard Shutdown
After a hard run, allow the engine to idle three minutes before shutdown in
order to stabilize the temperature of all engine parts. Quick shutdowns can
cause engine damage and prevent the turbocharger from being properly
lubricated.
CAUTION
Operating the engine below normal operating temperature for extended periods of
time will allow varnish/carbon deposits to build up on the valve stems and guides.
This will cause the valves to stick in the guides after the engine has been shut down
and could result in push rod damage when the engine is restarted. If the engine
has been operated below normal operating temperature for an extended period of
time (and the odor of raw diesel fuel is detected or unburned fuel can be seen at the
exhaust stack), the engine should be operated under "load" until normal operating
temperature is achieved BEFORE shutting down the engine.
On chassis equipped with an air starter, make sure that the air pressure gauge
reads a maximum of 120 psi before shutting down and parking for the night.
This will ensure sufficient air pressure for restarting the engine.
V-MAC IV Shutdown Option: Idle Cooldown
This feature provides a means of cooling down the engine and turbocharger.
If the idle cooldown option is enabled using VCADS Pro MACK Support
Software and the system senses that the turbocharger may be hot, the engine
will not shut down when the vehicle stops, the parking brake is set and the
key switch is turned to the OFF position. This feature allows the driver to lock
the truck and walk away while still providing adequate cooldown. All switched
accessories will then turn off once the engine has stopped. If this option is
set, the engine can be shut down immediately by cycling the key switch or by
pressing the shutdown override switch.
The idle cooldown timer is set to 3.5 minutes as soon as the engine load
exceeds 25%, provided that the engine has been running at least 60 seconds.
After the load drops below 25%, the timer begins counting down. If the key
switch is turned off before the timer expires, the engine will continue to run
until the timer reaches zero.
If a pyrometer is installed, the idle cooldown function will use the pyrometer
reading, shutting the engine down when the temperature drops below 232°C
(450°F), or after 3.5 minutes, whichever comes first.
The default for this option is set at OFF from the factory.