69570 Mercruiser SCREW, (#10-16 x .750), VALVE BODY TO RESERVOIR

Illustration 1 g00930387
(1) Expansion tank
(2) Radiator
(3) Separate circuit water pump
(4) Aftercooler
(5) Power train oil cooler
(6) Jacket water pump
(7) Cab heater
(8) Water temperature regulator housing
(9) Hydraulic oil cooler
(10) Engine oil cooler
(11) Turbocharger
(12) Cylinder block Note: Coolant ports (C1 through C9) are used for testing and for troubleshooting the cooling system. The routing of the cab heater lines that are shown is the latest design.Separate Circuit Aftercooling
The flow of coolant from radiator (2) is divided into two paths at an elbow that is located at the bottom of the radiator. The coolant flows to separate circuit water pump (3). The coolant then flows to aftercooler (4) from separate circuit water pump (3). The coolant is then returned back to the radiator. The coolant from the aftercooler does not flow through the water temperature regulators.Jacket Water Cooling Circuit
The other part of the coolant flows into jacket water pump (6) from the same elbow at the bottom of the radiator. The coolant flow splits and part of the coolant is sent through engine oil cooler (10).The coolant flows through engine oil cooler (10). The coolant enters cylinder block (12) at the right rear cylinder. The coolant flows to both sides of the block through distribution manifolds. The distribution manifolds are connected to the water jacket of all the cylinders. The main distribution manifold is located just above the main bearing oil gallery. A portion of the coolant from jacket water pump (6) flows through power train oil cooler (5). The other part of the coolant flows to hydraulic oil cooler (9) before entering the cylinder block at the front of the engine.The coolant flows upward through the water jackets. The coolant flows around the cylinder liners from the bottom to the top. The water jacket is made smaller near the top of the cylinder liners. The hottest temperature is near the top of the cylinder liners. This shelf causes the coolant to flow faster for better liner cooling. Coolant from the top of the liners flows into the cylinder head which sends the coolant around the parts which have the hottest temperature. Coolant then flows to the top of the cylinder head. Coolant flows through an elbow. Coolant enters a water manifold at each bank of cylinders. Coolant flows through the water manifold to water temperature regulator housing (8).Water temperature regulator housing (8) has an upper flow section and a lower flow section. The water temperature regulator housing uses four water temperature regulators. The sensing bulbs of the four water temperature regulators are in the coolant in the lower section of the water temperature regulator housing. Before the regulators open, cold coolant is sent through the bypass line. This coolant is sent back to the inlet of jacket water pump (6). As the temperature of the coolant increases, the regulators start to open and coolant flow in the bypass line is restricted. All coolant is sent to radiator (2). Also, coolant flows from upper part of water temperature regulator housing (8) to the bearing housing for turbocharger (11). The coolant is then returned to expansion tank (1).