Holiday 2002 NEPTUNE, Owner'S Manual

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Chassis Information
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2 0 0 2 N E P T U N E
10 • 305
The diesel engine uses compression to ignite the fuel/air charge. To increase
compression inside the combustion chamber (resulting in increased power out-
put) a turbocharger is added to the engine. The turbocharger is a paired housing
assembly with impellers inside each housing connected by a shaft. One
impeller is propelled by the engine exhaust, which drives the other impeller.
The function of the other impeller is to increase compression inside the com-
bustion chamber by forcing air into the intake manifold. This process works
well, however, the intake air charge is heated two different ways. Through con-
vection by the exhaust gases driving the turbocharger, and when air is com-
pressed. This has a negative effect inside the combustion chamber resulting in
lost power potential. Therefore, a Charge Air Cooler (CAC) is installed to cool
the intake air before it enters the engine. The Charge Air Cooler (CAC) may be
mounted to either the top or side of the radiator. Outside ambient air passing
through the CAC core will cool the engine's intake air charge.
Air leaving the turbocharger intake air is compressed, and heated to approx-
imately 300 - 375 degrees Fahrenheit, depending on the engine load and 100%
fuel. The CAC will reduce this hot air to the engine manufacturer's specified
air intake temperature before the air reaches the engine intake manifold.
Reducing intake air temperatures might reach 104 degrees. Lower intake air
temperatures reduce exhaust emissions, improve fuel economy and increase
horsepower. The CAC will continually expand and contract up to ¼ inch as the
driver increases and decreases throttle.
Visually inspect the charge air cooler, every six months, for dirt and debris
that may be blocking the fins. If, for any reason, the motorhome blows an oil
line, there is a possibility that the oil will coat the fins of the CAC. Once a
blown oil line has been repaired, have the CAC thoroughly cleaned.
Rear mounted radiators, with a top mounted CAC, will require more main-
tenance than a side mounted CAC. Litter and dust along the roadway may
restrict the airflow on this type of system. During each oil change have the
radiator shroud inspected for foreign objects that may be causing restriction.
Spraying degreaser on the charge air cooler, as well as using a steam clean-
er, will not harm the CAC. However, keep in mind that high-pressure water
placed too close to the component may bend the fins. The recommended clean-
ing procedure for the CAC, and the radiator, is to use a bucket of mild soap
and water. Carefully wash with a bristle brush. To rinse, use a garden hose with
minimum water pressure, standing back a distance to avoid bending the fins.
CHARGE AIR
COOLER
OM090388