880686T18 Mercury GEAR HOUSING ASSEMBLY, Complete

Illustration 1 g00697237
Cooling System Schematic
(1) Cylinder head
(2) Water temperature regulator housing
(3) Bypass hose
(4) Cylinder block
(5) Oil cooler
(6) Water pump
(7) Radiator Water pump (6) is located on the right front side of cylinder block (4). The water pump is belt driven from the crankshaft pulley. Coolant from the bottom of radiator (7) is pulled into the bottom inlet of the water pump by the impeller rotation. The rotation of the impeller in the water pump forces the coolant through the cooling system. The coolant exits the back of the water pump directly into the oil cooler cavity of the cylinder block.All of the coolant passes through the core of oil cooler (5) and the coolant then enters the internal water manifold of cylinder block (4). This manifold distributes the coolant to water jackets that are around the cylinder walls.
Illustration 2 g00697245
Water Lines Group
(1) Cylinder head
(2) Water temperature regulator housing
(3) Bypass hose
(6) Water pump
(8) Outlet to radiator
(9) Water temperature regulator that is partially open
(10) Air vent valve that is located in the flange of thermostat
(11) Coolant return from the air compressor (if equipped)
(12) Port for water pump outlet pressure for engine diagnosis Note: Some commercial engines have a bypass hose (3). This hose is used only on engines which use an automotive type radiator that is supplied by Caterpillar.Note: Later thermostats have an air vent valve (10). This air vent valve allows air to escape from the cooling system while coolant is added.
Illustration 3 g00697239
Water Lines Group
(2) Water temperature regulator housing
(3) Bypass hose
(6) Water pump
(8) Outlet to radiator
(9) Water temperature regulator that is partially open
Illustration 4 g00697251
Water Pump
(13) Pump outlet pressure (alternate heater supply)
(14) Port for coolant supply to aftercooler (if equipped)
(15) Coolant return ports from the heater
(16) Alternate pump outlet pressure for engine diagnosis From the cylinder block, the coolant flows into passages that are in cylinder head (1). These passages send the flow of coolant around the following items:
Unit injector sleeves
Inlet passages
Exhaust passagesThe coolant now enters water temperature regulator housing (2) at the front right side of cylinder block (4).Water temperature regulator (9) controls the direction of flow. If the temperature of the coolant is below normal, then the water temperature regulator is closed. The coolant is directed through bypass hose (3) and into the top inlet of water pump (6). When the coolant gets to the correct temperature, the water temperature regulator will open. Most of the coolant goes through outlet (8) to the radiator for cooling. The remainder flows through the bypass hose and into the water pump.Note: Water temperature regulator (9) is an important part