PLATE 4825134 - Caterpillar

Cold Operation
Illustration 1 g00882975
Schematic of the cooling system during cold operationNote: The schematic examples are intended to illustrate the relationships between the cooling system components. Individual installations will have some differences.The 3618 Engine has a combined circuit cooling system. This single circuit uses two water pumps that are driven by the engine. One remote heat exchanger cools the water from the aftercooler/oil cooler circuit which cools the water from the jacket water circuit.Note: The cooling water for the heat exchanger may be supplied by a remote sea water pump or by an auxiliary water pump that is driven by the engine.When a cold engine is started, the water in the cooling system is below normal operating temperatures and the water temperature regulators are closed. Before the engine begins to warm the coolant and the water temperature regulators begin to open, the combined circuit cooling system may be considered as two separate circuits.The cooling system has several orifices. The orifices' sizes and the orifices' positions are adjusted during the engine commissioning. The orifices balance the flow between the side for the jacket water and the side for the ACOC. The orifices also control the pressure and velocity of the water through the coolers.Jacket Water Circuit
Water from a remote water temperature regulator housing is drawn through an orifice by the jacket water pump. The water is pumped into the cylinder block.The water flows around the cylinder liners. The water is pumped through the top of the cylinder block into the cylinder heads. The water flows around the ports for the inlet air, the ports for the exhaust gas, and the exhaust valve seat inserts. Each bank of cylinders has a water manifold. Water from both banks is pumped from the cylinder heads into the water manifolds. Water from both manifolds flows through piping back to the water temperature regulator housing and to the jacket water pump.When the temperature of