818171T Mercruiser VALVE-BALL

Illustration 1 g00423398
Cooling System Schematic
(1) Temperature regulator housing
(2) Radiator
(3) Bypass tube
(4) Water pump
(5) Engine oil cooler
(6) Return manifold
(7) Supply manifold in the block
(8) Cylinder head
(9) Cylinder liner The water pump is driven by a gear. The water pump is located on the right hand side of the engine. The water pump supplies the coolant for the engine cooling system. The coolant is supplied to the following components:
Engine oil cooler (5)
Cylinder head (8)
Cylinder liner (9)
Air compressor (not shown)
Coolant conditioner element (not shown)Note: In air-to-air aftercooled systems, a coolant mixture with a minimum of 30 percent ethylene glycol base antifreeze must be used for efficient water pump performance. This mixture keeps the cavitation temperature range of the coolant high enough for efficient performance.
Illustration 2 g00423399
Typical right side of engine
(1) Temperature regulator housing
(4) Water pump
(5) Engine oil cooler
Illustration 3 g00423400
Typical rear of engine
(6) Return manifold
Illustration 4 g00543009
Right side engine
Coolant from engine oil cooler to the supply manifold (7)
The water pump (4) pulls the antifreeze coolant solution from the bottom of radiator (2). The rotation of the water pump's impeller creates coolant flow within the cooling system. The water pump is located on the right hand side of the front timing gear housing.The water pump impeller is rotated at 1.17 times the engine speed by an idler gear. The idler gear is turned by the crankshaft gear. The water pump shaft is supported by two ball bearings. One ball bearing is located in the water pump housing. The other ball bearing is located in the front timing gear housing. The water pump impeller face is open. The impeller vane is radial. The impeller is made out of cast iron. The rear cover is made out of aluminum. The rear cover is a die casting. The water pump seal is a cartridge seal. The water pump seal is located on the inlet side of the pump in order to provide good water flow around the seal for cooling. The antifreeze coolant solution is pumped through the engine oil cooler (5). The antifreeze coolant solution then goes into the supply manifold (7). The supply manifold is located in the cylinder block. The supply manifold distributes the antifreeze coolant solution at each cylinder. The antifreeze coolant solution then flows around the upper portion of the cylinder liner. The antifreeze coolant solution cools the upper portion of the cylinder liner. At each cylinder, the antifreeze coolant solution flows from the cylinder liner to the cylinder head. The cylinder head is divided into single cylinder cooling sections. In the cylinder head, the antifreeze coolant solution flows across the center of the cylinder and across the injector seat boss. At the center of the cylinder, the antifreeze coolant solution flows around the injector sleeve over the exhaust port. The antifreeze coolant solution then exits into the return manifold (6). The return manifold collects the antifreeze coolant solution from each cylinder and the return manifold directs the flow to the temperature regulator housing (1). When the temperature regulator is in the closed position, the antifreeze coolant solution flows through the regulator. This allows the antifreeze coolant solution to flow directly back to the water pump by bypassing the radiator. The water pump then recirculates the antifreeze coolant solution. With the temperature regulator in the open position, the antifreeze coolant solution is directed through the radiator and back to the water pump inlet.Supply Manifold
Cooling is provided for only the portion of the cylinder liner above the seal in the block. The antifreeze coolant solution enters the block at each cylinder through the slits in the supply manifold. The supply manifold is an integral casting in the block. The coolant flows around the circumference of the cylinder liner and into the cylinder head through a single drilled passage for each liner. The coolant flow is split at each liner so that 60 percent flows around the liner and the remainder bypasses the liner and flows directly to the cylinder head.
Illustration 5 g00423402
Front right side of engine
(1) Temperature regulator housing
(2) Coolant temperature sensor
Illustration 6 g00423403
Temperature Regulator Housing
(3) Return manifold
(4) Closed position The coolant temperature regulator is a full flow bypass type that is used to control the outlet temperature of the coolant. When the engine is cold, the regulator is in the closed position (4). This allows the coolant to flow through the regulator from the return manifold (3). This allows the coolant to bypass the radiator. The coolant goes directly to the water pump for recirculation. As the coolant temperature increases, the temperature regulator begins to open directing some of the coolant to the radiator and bypassing the remainder to the water pump inlet. At the full operating temperature of the engine, the regulator moves to the open position. This allows all the coolant flow to be directed to the radiator. The coolant then goes to the water pump. This route provides the maximum heat release from the coolant. A vent line is recommended from the manifold to the radiator overflow tank in order to provide venting for the cooling system. The recommended vent line is a #4 Aeroquip.Coolant Conditioner (If Equipped)
Illustration 7 g00423404
Coolant Conditioner
(1) Engine oil cooler
(2) Outlet hose
(3) Inlet hose
(4) Coolant flow to cylinder head
(5) Engine oil cooler
(6) Coolant flow from water pump
(7) Coolant conditioner element
(8) Coolant conditioner base Pitting has been caused by some operating conditions. The pitting has been observed on the following areas:
Outer surface of the cylinder liners
Surface of the cylinder block next to the linersThe pitting has been caused by the following reasons:
Corrosion
Cavitation erosion