PREVOST X3-45 COMMUTER User Manual

SECTION 05: COOLING SYSTEM
DOB 1300-1556 | X3-45 Commuter PA-1648 Maintenance Manual First release Oct 2020
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2. DESCRIPTION
A radiator and variable speed electric cooling
fans are used to effectively dissipate the heat
generated by the engine. A charge air cooler
(CAC) mounted next to the radiator is also used
to cool the compressed air flow coming from the
turbocharger before it reaches the engine intake.
All components, along with the fans circuit
breaker box, are grouped together and mounted
on the L.H. side of the engine compartment to
form an easy to access and service “cooling
assembly” (Figure 1).
WARNING
WHEN THE ENGINE IS RUNNING
Cooling fans may activate at any moment.
Keep hands away from cooling fans or keep
the radiator door closed.
WARNING
Cooling fans may be running when the
engine is shut down in the following
conditions:
-
If a High Exhaust Temperature condition
exists (e.g. following regeneration).
- During "Motor Test" sequence.
An engine mounted centrifugal water pump is
used to circulate the engine coolant in the
cooling circuit. The pump works in conjunction
with a full blocking-type thermostat positioned in
the water outlet passage, controlling the coolant
flow and providing fast engine warm-up and
regulated coolant temperature.
The engine coolant is drawn from the lower
portion of the radiator by the water pump and is
forced through the transmission cooler before
going through the oil cooler and into the cylinder
block.
From the cylinder block, the coolant passes up
through the cylinder head and, when the engine
is at normal operating temperature, it goes
through the thermostat housing and into the
upper portion of the radiator. The coolant then
passes through a series of tubes where its heat
is dissipated by airstreams created by the
revolving fans and the motion of the vehicle.
Upon starting a cold engine or when the coolant
is below normal operating temperature, the
closed thermostat directs coolant flow from the
thermostat housing through the by-pass tube to
the water pump. Coolant is recirculated through
the engine to aid engine warm up.
When the thermostat opening temperature is
reached, coolant flow is divided between the
radiator inlet and the by-pass tube. When the
thermostat is completely open, all of the coolant
flow is directed to the radiator inlet.
The system fill cap is on the top of a plastic
recovery tank located next to the surge tank
(Figure 2), a cap is also present on the metal
surge tank to act as a pressure cap, The
thermostat is located in the housing bolted to the
engine on the L.H. side.
WARNING
Do not open the surge tank pressure cap
unless a large amount of liquid must be added.
Always use the recovery tank fill cap to add
coolant to the vehicle during normal operation
(level check).
WARNING
The system pressure must be relieved using
the pressure relief valve.
Never open the surge tank pressure cap
without making sure first that the system is
completely depressurized.
Coolant under
pressure (hot or not) may cause serious
injuries and eyes damages.
NOTE
Close the valve after releasing the pressure.
The engine cooling system also provides hot
coolant for the vehicle heating system. Refer to
section 22, ”HEATING AND AIR
CONDITIONING" in this manual for information
relating to heating system water circulation.

PREVOST X3-45 COMMUTER Specifications

General

Engine	Volvo D13
Transmission	Allison B500
Fuel Type	Diesel
Length	45 ft (13.7 m)
Width	102 in (2.6 m)
Horsepower	500 hp
GVWR	54, 000 lbs
Height	141 in