CHASSIS INFORMATION - 10
198
CAY M A N 2 0 0 7
After leaving the turbocharger, intake air
is compressed and heated to approximately
300º to 375º F. depending on the engine load
and throttle position. Before air enters the
intake manifold, the CAC cools the intake
air temperature to the engine manufacturer
speci cations. Lowered intake air temperatures
reduce exhaust emissions, improve fuel
economy and increase horsepower. The CAC
will continually expand and contract up to ¼" as
throttle increases and decreases.
Cleaning and Maintenance:
Regular maintenance includes draining
the engine coolant, ushing/cleaning
the cooling system, inspecting the
water pump standpipe, replacing
the thermostat, gasket and seal, and
replacing the coolant and SCA element.
Inspect the charge air cooler every six
months and remove dirt and debris that
may block the ns. If the motorhome
develops an oil leak, there is a possibility
that the oil will coat the ns of the CAC.
Dust will adhere to the oil lm, clog the
ns and reduce cooling ef ciency. When
the oil leak is repaired, the CAC must be
thoroughly cleaned.
During each oil change inspect the
engine side of the radiator/CAC
assembly for foreign objects that may
cause restriction.
Spraying degreaser on the charge air
cooler, as well as using a steam cleaner,
will not damage the CAC. However,
pressure washer and steam cleaner
nozzles placed too close to the CAC
can bend the fi ns. The recommended
cleaning procedure for the CAC and the
radiator is to use a bucket of mild soap
and water. Carefully wash with a bristle
brush then rinse using a garden hose,
with minimum water pressure, standing
back a distance to avoid bending the ns.
When performing maintenance, it is also
necessary to inspect other components
of the cooling system. The charge
air cooler and radiator also requires
an inspection for cracks, broken
welds, secure mounting, and general
cleanliness.
Coolant Hoses:
Rotten, swollen and worn hoses, as well
as loose connections, are frequent causes of
coolant system problems. Overheating can be
caused by a collapsed hose or a clog caused by
rubber shedding from a rotten hose. Replace any
hose found to be cracked, swollen or damaged.
Connections should be inspected periodically
and hose clamps tightened.
Every 12 months:
Inspect all hoses, clamps, and ttings for
leaks due to cracking, softness, and loose
clamps/ ttings. Look for signs of uid leaks,
damaged end ttings, ballooning, chafed,
kinked, or crushed hoses, and loose clamps and
ttings. Correct any de ciencies found.
TRANSMISSION
The Allison World transmission incorporates
the World Transmission Electronic Control
(WTEC) system. The system consists of ve
major components connected by a wiring
harness: the Electronic Control Unit (ECU),
engine throttle position sensor, three-speed
sensors, remote shift selector (keypad) and
the control module. The ECU processes
information received from the throttle position
sensor, speed sensor, pressure switch and shift
selector to provide optimum shift quality. This
is accomplished by matching transmission and
engine RPM during a shift to establish a desired
shift pro le within the ECU. Another feature
of the transmission is the ability to “learn” or
“adapt.” The electronic control system optimizes
shift quality by using “Adaptive Shifting.”
A wide variety of varied shift conditions
is required before optimizing shift quality.
Generally, ve typical shifts of a consistent shift
type are needed to optimize shift quality.
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