SECTION 2.

25
COOLING SYSTEM DESCRIPTION

COOLING SYSTEM DESCRIPTION EXHAUST MANIFOLD

The cooling system consists of the following compo- From each cylinder head, water passes up through the
nents: water outlet elbow connection (see Figure 2.25-1) to
one segment of the water-jacketed exhaust mani-
• Jacket Water Circuit fold(s) and exits through the water outlet port to the
– Jacket Water Header/Jacket Water water manifold (see Figure 2.25-2 and Figure 2.25-3).
Each exhaust manifold assembly is composed of indi-
– Exhaust Manifold vidual water-cooled segments.
– Jacket Water Pump
EXHAUST
– Water Manifold MANIFOLD
– Remote Heat Transfer Device (Customer-
Supplied)
– Jacket Water Temperature Control Valve
– Surge Tank (Optional)
• Auxiliary Cooling Water Circuit
– Auxiliary Water Pump
– Intercooler(s)
– Oil Cooler
WATER OUTLET
ELBOW
– Auxiliary Water Temperature Control Valve
– Auxiliary Water Heat Transfer Device Figure 2.25-1 Water Outlet Elbow
(Customer-Supplied)
JACKET WATER HEADER/JACKET WATER THERMOSTAT WATER
HOUSING MANIFOLD
The cooling water passageways in both the crankcase
CYLINDER EXHAUST
and cylinder heads comprise the jacket water system. HEADS MANIFOLD
The jacket water header is integrally cast within the
crankcase. Cooling water circulates around the cylin-
der liners inside the cylinder block. Water flows up
through the water passage openings in the deck of
each cylinder head, flows around the valve seats and
exhaust guides, and up to the water-cooled exhaust
manifold(s).

JACKET WATER
PUMP

Figure 2.25-2 6 Cylinder Engine Cooling Components

FORM 6300 2.25-1

COOLING SYSTEM DESCRIPTION

JACKET WATER PUMP The thermostats start to open as the engine warms up
to its normal operating temperature. A portion of the
A belt driven water pump is mounted on the front of the
coolant is diverted to the remote heat transfer device,
engine (see Figure 2.25-2 and Figure 2.25-3). Cooling
which absorbs the heat and directs the coolant back to
water exiting the pump is piped to the jacket water
the jacket water pump. The coolant supply from the
headers.
heat transfer device mixes with that portion of the cool-
WATER MANIFOLD ant which continues to flow down the bypass tube(s) to
provide a blend that is within the normal range.
The water manifold (see Figure 2.25-2 and
Figure 2.25-3) receives the cooling water flowing out AUXILIARY WATER PUMP
of each segment of the exhaust manifold and routes it
All auxiliary water pumps are belt driven. The 6 cylin-
to the cluster thermostat housing.
der auxiliary water pump is located on the lower right
REMOTE HEAT TRANSFER DEVICE front of the engine (see Figure 2.25-4), while 12 cylin-
der engine auxiliary water pumps are located on the
The remote heat transfer device may be a radiator,
lower left front side (see Figure 2.25-3).
cooling fan, cooling tower, heat exchanger, or some
other device.
AUXILIARY WATER REMOTE HEAT TRANSFER
DEVICE
The auxiliary, or secondary, heat transfer device may
be a radiator, cooling fan, cooling tower, heat
exchanger, or some other device. The heat transfer
device provides cooling for the auxiliary system cool-
ant.

THERMOSTAT
HOUSING

AUXILIARY
WATER PUMP

Figure 2.25-4 6 Cylinder Auxiliary Water Pump

INTERCOOLER(S)
The intercooler(s) cool the inlet air to the turbocharg-
ers to provide denser air to the turbochargers. The
intercooler(s) are located at the rear of the engine (see
WATER Figure 2.25-5).
MANIFOLD

JACKET AUXILIARY
WATER PUMP WATER PUMP

Figure 2.25-3 12 Cylinder Engine Cooling Components

CLUSTER THERMOSTAT HOUSING

The thermostats are enclosed in the cluster thermo-
stat housing at the outlet end (front) of the water mani-
fold (see Figure 2.25-2 and Figure 2.25-3). By
regulating the circulation of coolant, the thermostats
control the jacket water temperature. The thermostats
remain closed while the engine is warming up, so cool-
ing water is circulated through the engine water jacket
only. INTERCOOLER

Figure 2.25-5 Intercoolers – 12 Cylinder Engine

2.25-2 FROM 6300

 COOLING SYSTEM DESCRIPTION

OIL COOLER
The coolant flows from the intercooler(s) to the oil
cooler. The oil cooler is a tube and baffle type assem-
bly (see Figure 2.25-6 and Figure 2.25-7). While the
coolant flows through a bundle of tubes in the oil
cooler, the lube oil circulates around them. Heat from
the oil passes through the tubes to the coolant, which
carries it to a heat transfer device for dissipation. From
the heat transfer device, the coolant passes back to
the auxiliary water pump to repeat the circuit.

OIL COOLER

Figure 2.25-6 Oil Cooler – 6 Cylinder Engine

OIL COOLER

Figure 2.25-7 Oil Cooler – 12 Cylinder Engine

FROM 6300 2.25-3

COOLING SYSTEM DESCRIPTION

2.25-4 FROM 6300