The cooling system keeps the engine within a designated temperature range.
The major components of the cooling system include the following:
• Radiator and fan combination (chassis components)
• Water pump assembly
• Thermostat assembly
• Oil system module assembly
• EGR cooler assembly
A belt-driven centrifugal water pump is set into the front cover. The front cover has three related passages. One passage channels coolant from the water pump to the crankcase, the second returns coolant to the water pump, and the third (a bypass) channels coolant back to the water pump when the thermostat is closed.
Incoming coolant flows from the bottom of the radiator through a water inlet elbow to the front cover and water
pump. Coolant is pumped to the crankcase through a passage in the front cover and crankcase.
Water jackets in the crankcase direct coolant from front to rear, distributing coolant evenly to the lower
sections of the cylinder sleeves. Coolant flow is directed tangent to each cylinder sleeve, causing a swirling motion up to the cylinder head. The swirling action improves heat absorption.
Coolant flows from the cylinder sleeve areas in three ways:
• Coolant flows into the oil system module assembly through the right side of the crankcase, passes through the oil system module, and returns through a tube to the front cover.
• Coolant is routed through hoses to and from the air compressor on the left side of the crankcase.
• Coolant exits the crankcase at the upper end of each cylinder sleeve bore and is distributed evenly through metering holes in the cylinder head gasket. Coolant then flows through the cylinder head (back to front) to the thermostat.
The EGR cooler receives coolant from the front cover. Coolant flows from the front of the cooler and exits the
rear of the cooler into the rear of the cylinder head. A deaeration port is on top of the EGR cooler.
