Engine Lubrication: Description and Operation

- The lubrication system is a force-fed circulating design and oil pressure is regulated by relief valve built-in the oil pump.
- The oil pump utilizes a thin, large-diameter trochoid design to accommodate the high engine output. This pump is directly driven by the crankshaft.
- The full-flow, paper element type oil filter is provided to improve engine reliability and has a built-in by-pass valve to bypass the engine oil if filter is clogged.
- The oil pan is provided with baffle plates to eliminate the effect of oil suction caused by oil level variations during operation.
- Engine oil discharged from oil pump is delivered to the journal bearings, connecting rod bearings, etc., via the oil passage (on the lower right side of the cylinder block), oil filter, and the oil gallery (on the right of the cylinder block) to provide proper lubrication and cooling.
- Engine oil is also fed under pressure to the cylinder head valve mechanism after the flow is regulated by the orifice provided in the oil gallery.





Lubrication Lines

Oil Pump





- The trochoid oil pump utilizes an internal oil circulation design which is accomplished by an inner rotor and outer rotor built into the pump body. When the inner rotor is driven by the crankshaft, the outer rotor is rotated, changing the size of the space between the two rotors (because of the different number of teeth used on the rotors).
- Engine oil is sucked into the large space created near the inlet side. It is then carried over to the discharge port and discharged due to it being gradually pressurized as the space carrying it becomes smaller. Oil pressure is regulated by the relief valve located on the discharge side. Excess oil is directly returned to the suction port.

Oil Filter





The oil filter is a full-flow cartridge type that utilizes a paper element. It also has a built-in by-pass valve. The filter element has a special pleat design to increase the effective filtering area.

Oil Pan & Oil Strainer





- The oil pan is joined to the cylinder block via liquid gasket. The oil strainer is a metal net type and removes large foreign particles from the engine oil. It is located in the middle of the oil pan. The pipe from the strainer is connected to the suction port on the left side of the cylinder block.
- Baffle plate is placed in the oil pan and the lower side of the cylinder block to stabilize the oil level and strengthen the oil pan.

Oil Pressure Switch





The oil pressure switch is located on the front right upper portion of the cylinder block. The purpose of this switch is to monitor the operation of the oil pump as well as the lubricating oil pressure when the engine is running.
- When oil pressure does not build up (with ignition switch "ON"):
The diaphragm is pushed toward the cylinder block by spring force (equivalent to the specified oil pressure). This closes the contact point to illuminate the oil pressure warning light in the combination meter.
- When oil pressure reaches the specified value (after engine starts):
After oil pressure reaches the specified value of [14.7 kPa (0.15 kgf/cm2, 2.1 psi)] , the diaphragm, pushed by oil pressure, overcomes the spring force. This opens the contact point to turn the oil pressure warning light OFF.