17151-ZV1-850 Honda GASKET, IN. MANIFOLD (Honda Code 4692414).

Illustration 1 g01155880
(1) Cylinder head
(2) Water temperature regulator housing
(3) Expansion tank
(4) Bypass hose
(5) Radiator
(6) Cylinder block
(7) Engine oil cooler
(8) Transmission oil cooler (if equipped)
(9) Water pumpWater pump (9) is on the right side of the cylinder block. The water pump is gear-driven from the front gear group. Coolant can enter the water pump in two places:
Inlet at the bottom of the water pump
Bypass hose (4) at the top of the water pumpCoolant from the bottom of the radiator (5) is pulled into the bottom inlet of the water pump (9) by impeller rotation. The coolant exits the back of the pump directly into engine oil cooler (7). Some of the coolant is also diverted to transmission oil cooler (8) (if equipped).Some of the coolant passes through the core of engine oil cooler (7) and some of the coolant passes through the core of transmission oil cooler (8) (if equipped). The coolant then enters the internal water manifold of the cylinder block. The manifold disperses the coolant to water jackets around the cylinder walls.From the cylinder block, the coolant flows into passages in the cylinder heads. The passages send the flow around the unit injector sleeves and the inlet and the exhaust passages. The coolant now enters water temperature regulator housing (2) at the front of the cylinder head.
Illustration 2 g06431892
(2) Water temperature regulator housing
(4) Bypass hose
(9) Water pump
(10) Outlet to the radiator
(11) Inlet from the radiatorTwo water temperature regulators control the direction of coolant flow. When the coolant temperature is below the normal operating temperature, the water temperature regulators are closed. The coolant is directed through bypass hose (4) and into the top inlet of the water pump. When the coolant temperature reaches the normal operating temperature, the water temperature regulators open. When the water temperature regulators are open, the bypass is closed. Most of the coolant goes through the outlet to the radiator for cooling. The remainder flows through bypass hose (4) and into the water pump.Note: The water temperature regulators are an important part of the cooling system. The water temperature regulators divide coolant flow between the radiator and the bypass hose to maintain the normal operating temperature. If the water temperature regulators are not installed in the system, there is no mechanical control, and most of the coolant will travel the path of least resistance through the bypass hose. This action will cause the engine to overheat in hot weather and the engine will not reach normal operating temperature in cold weather.Cooling System Protection
The engine on this machine is equipped with dual sensor cooling protection. There is a coolant pressure sensor on the inlet and outlet of the water pump that will monitor the cooling system pressures.When a cooling component fails or a systemic issue occurs, causing high or low coolant pressure or loss of flow through the cooling system, a code will appear that will vary in level of severity up to and including 100% engine derate.Coolant Conditioner (If Equipped)
Some conditions of operation can cause pitting. This pitting is caused by corrosion or by cavitation erosion. A corrosion inhibitor is a chemical that provides a reduction in pitting. The addition of a corrosion inhibitor can keep this type of damage to a minimum.The coolant conditioner element is a spin-on element that is similar to the fuel filter and to the oil filter elements. The coolant conditioner element attaches to the coolant conditioner base that is mounted on the front of the engine. Coolant flows from the water pump to the coolant conditioner base and back to the cylinder block. Coolant constantly flows through the coolant conditioner element when the valves are in the OPEN position.The element has a specific amount of inhibitor for acceptable cooling system protection. As the coolant flows through the element, the corrosion inhibitor goes into the solution. The corrosion inhibitor is a dry solution, so the inhibitor dissolves. The corrosion inhibitor then mixes to the correct concentration. Two basic types of elements are used for the cooling system. The two elements are the precharge elements and the maintenance elements. Each type of element has a specific use. The elements must be used correctly to get the necessary concentration for cooling system protection. The elements also contain a filter. The coolant conditioner elements should remain in the system after the conditioner material has dissolved.The precharge element contains more than the normal amount of inhibitor. The precharge element is used when a system is first filled with new coolant. This element must add enough inhibitor to bring the complete cooling system up to the correct concentration.The maintenance elements have a normal amount of inhibitor. The maintenance elements are installed at the first change interval. Enough of inhibitor is provided by the maintenance elements to maintain the corrosion protection at an acceptable level. After the first change interval, only maintenance elements are installed. To provide the cooling system with protection, maintenance elements are installed at specific intervals.