Holiday imperial 2001, Owner'S Manual, Page: 265 / 301

Chassis Information
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I M P E R I A L
1 0 • 2 6 5
The diesel engine operates differently from the conventional gasoline
engine. Gasoline engines control engine speed using a butterfly throttle
plate controlling air/fuel mixture inlet flow. As the throttle plate opens,
vacuum created by the piston velocity draws the metered fuel/air charge
into the combustion chamber, then ignited from a controlled electric ignition
source. Closing the throttle plate limits the fuel/air supply, slowing engine
speed, increasing intake manifold vacuum.
The diesel engine in the motorhome controls engine speed by varying
fuel supply only. No throttle plates are used. An exhaust driven turbine sys-
tem (turbocharger) compresses the fresh air supply into the engine. The fuel
is injected under pressure into the combustion chamber. Ignition of fuel/air
charge occurs from heat generated by rapid high compression. The turbo
boost gauge registers amount of intake manifold compression measured in
lbs./in². Therefore, no intake manifold vacuum exists.
Diesel engine RPM (revolutions per minute) operating speeds are gener-
ally much lower than that of the gasoline engine. Peak torque and horsepow-
er output values occur at much lower engine speeds. Idle speeds between the
two engine types are similar, however maximum engine speeds are quite dif-
ferent. The gasoline engine generally is not regulated to a maximum engine
speed. The maximum engine speed on a diesel engine is controlled by an
engine speed governor set by the engine manufacturer.
WARNING: Do not operate a diesel engine where there are or
can be combustible vapors. Vapors can be drawn through air
intake system and cause engine acceleration and over-speeding,
resulting in fire, explosion and extensive property damage.
Numerous safety devices are available, such as air intake shut-
off devices, to minimize risk of over-speeding where an engine
(due to its application) might operate in a combustible environ-
ment, such as fuel spills or gas leaks. Equipment owner and
operator is responsible for safe operation of engine. Consult
your engine authorized repair location for future information.
The maintenance guidelines found in the Cummins O & M manual is
recommended for the engine. When followed it will help with a longer life,
better performance and more cost efficient operations. A good maintenance
schedule begins with a daily awareness of the engine and it’s various sys-
tems.
The engine is equipped with an intake manifold grid heater. The grid
heater helps engine starting in cold weather. Intake manifold air temperature
is monitored by the Electronic Control Module on the engine. If intake man-
ifold temperature is below specified level (approximately 40º F.) manifold
grid heater will be activated. Grid heater activation is indicated by the
WAIT TO START indicator lamp.
WARNING: Use of ether starting fluids may cause an explosion
upon grid heater activation.
ENGINE -
GENERAL
INFORMATION
ISC ENGINE