19292-ZW5-000 Honda SPRING, RELIEF VALVE (Honda Code 5891395).

Illustration 1 g01172437
Lubrication system schematic
(1) Passage to the rocker arms
(2) Cylinder head gallery
(3) Piston cooling jets
(4) Passage to pushrod lifters
(5) Main bearings
(6) Camshaft bearings
(7) Turbocharger oil supply line
(8) Main oil gallery
(9) Passage to front housing
(10) Passage to oil pump idler gear bearing
(11) Passage to camshaft idler gear bearing
(12) Oil filter bypass valve
(13) Passage
(14) Oil cooler bypass valve
(15) Engine oil filter
(16) Engine oil cooler
(17) Auxiliary engine oil filter (if equipped)
(18) Engine oil pump
(19) Oil pump bypass valve
(20) Engine oil panEngine oil pump (18) is mounted to the bottom of the cylinder block inside the engine oil pan (20). The engine oil pump (18) pulls oil from engine oil pan (20). The engine oil pump pushes the oil through the passage to the engine oil cooler (16). Oil then flows through engine oil filter (15). The filtered oil then enters the turbocharger oil supply line (7) and main oil gallery (8).The main oil gallery (8) distributes oil to main bearings (5), piston cooling jets (3), and camshaft bearings (6). Oil from main oil gallery (8) exits the front of the block. The oil then enters a groove that is cast in front housing (9).Oil enters the crankshaft through holes in the bearing surfaces (journals) for the main bearing (5). Passages connect the bearing surface (journal) for the main bearing (5) with the bearing surface (journal) for the connecting rod.The passage in front housing (9) sends the oil flow in two directions. At the upper end of the passage, oil is directed back into the block and up to cylinder head gallery (2) through passage (1) to the rocker arm mechanism. A passage (10) sends oil to the oil pump idler gear bearing.Oil from the front main bearing enters a passage (11) to the camshaft idler gear bearing. Oil passages in the crankshaft send oil from all the main bearings (5) through the connecting rods to the connecting rod bearings.The passages send oil from the camshaft bearings (6) to an oil passage in the side covers. The oil then enters a hole in the shafts to pushrod lifters (4). The oil lubricates the bearings of the lifter.Note: Engines that are equipped with an auxiliary oil filter (17) will receive oil at a port. The filtered oil will be returned to engine oil pan (20).The oil circuit consists of a common pressure circuit. The pressure circuit typically operates at a pressure of 240 kPa (35 psi) to 480 kPa (70 psi). The pressure circuit provides engine oil that has been filtered to the lubricating system of the engine. Oil is drawn from the engine oil pan (20). Oil is supplied through the engine oil cooler (16) and engine oil filter (15) to the engine.After the lubrication oil's work is done, the lubrication oil returns to the engine oil pan.The oil pump bypass valve (19) limits the pressure of the oil that is coming from the engine oil pump (18). The engine oil pump (18) can pump more than enough oil into the system. When there is more than enough oil, the oil pressure increases. When the oil pressure increases, the oil pump bypass valve (19) will open. This allows the oil that is not needed to go back to the suction side of the engine oil pump (18).The bypass valves (14) and (12) will open when the engine is cold (starting conditions). Opening the bypass valves achieves immediate lubrication of all components. Immediate lubrication is critical when cold oil with high viscosity causes a restriction to the oil flow through engine oil cooler (16) and engine oil filter (15). The engine oil pump (18) sends the cold oil through the bypass valves around the engine oil cooler (16) and engine oil filter (15) to the turbocharger oil supply line (7) and the main oil gallery (8) in the cylinder block.When the oil gets warm, the pressure difference in the bypass valves decreases and the bypass valves close. After the bypass valves close, there is a normal flow of oil through the engine oil cooler and the engine oil filter.The bypass valves will also open when there is a restriction in the engine oil cooler (16) or engine oil filter (15). This design allows the engine to be lubricated even though engine oil cooler (16) or engine oil filter (15) are restricted.The engine oil cooler bypass valve is also activated by pressure. If the oil pressure differential across the engine oil cooler reaches 125 30 kPa (18 4.5 psi), the valve will open. Opening the valve allows the oil flow to bypass the engine oil cooler (16).The main oil flow now reaches the main engine oil filter (15). When the oil pressure differential across the oil filter bypass valve (12) reaches 233 50 kPa (34 7 psi), the valve opens in order to allow the oil flow to go around the oil filter (15). The oil flow continues in order to lubricate the engine components. When the oil is cold, an oil pressure difference in the bypass valve also causes the valve to open. This bypass valve then provides immediate lubrication to all the engine components when cold oil with high viscosity causes a restriction to the oil flow through the engine oil filter (15). The bypass valve will also open when there is a restriction in the engine oil filter (15). This design allows the engine to be lubricated even though engine oil filter (15) is restricted.Note: Refer to Specifications, "Engine Oil Filter Base".Filtered oil flows through the main oil gallery (8) in the cylinder block. Oil is supplied from the main oil gallery (8) to the following components:
Piston cooling jets
Valve mechanism
Camshaft bearings
Crankshaft main bearings
Turbocharger cartridgeAn oil cooling chamber is formed by the lip that is forged at the top of the skirt of the piston and the cavity that is behind the ring grooves in the crown. Oil flow for