See Figure 3-1. As the oil is warmed to normal operating temperature, the oil is scavenged from the sump at the screened pick up (1) by the oil pump (2).
The oil pump (2) pressurizes the oil and the pressure maintains the flow of oil through the engine. The oil flows through a bypass valve and through the oil passages to the oil filter (3). If oil pressure exceeds 88 psi, the bypass valve is activated, rerouting oil back through the suction side of the oil pump.
The filtered oil flows into the oil lines up and over the top of the radiator/oil cooler assembly and down to the left side of the oil cooler (4). Flowing across the cooler, the cooled oil is routed up and over the radiator/oil cooler assembly and then down to the oil fitting (5) on the front of the crankcase.
At the crankcase oil fitting, oil is routed to three passages:
1. Oil entering the passage (6) on the water pump side lubricates the right main bearings. The oil flows in a groove in the main bearing then through a drilled hole in the crankshaft to lubricate the rear connecting rod journals.
2. Oil entering the middle passage (7) supplies oil to the front piston jet. The piston jets spray oil to cool the underside of the pistons.
3. See Figure 3-2. Oil entering the cam drive side passage (8) feeds the cam drive side main bearing. The oil flows in a groove in the main bearing then through a drilled hole in the crankshaft to lubricate the front connecting rod bearings.
From the cam drive side main bearing, the oil is routed in two directions:
- a. Oil is routed up to the cam drive triple gear bushing (9) where oil is routed along the shaft to the water pump impeller. The oil also flows to front cylinder head through an oil sending unit (10) which shuts off the oil pressure light when oil pressure reaches 13.8-34.5 kPa (2-5 psi). The oil passages continue on to the intake and exhaust cams (13) lubricating the cam journals through grooves in the bearings and to the secondary cam chain tensioner (12).
- b. The second set of passages from the cam drive side main bearings lead the oil flow to the primary cam chain tensioner and up to the secondary cam chain tensioner, the rear cylinder head and the rear intake and exhaust jam journals. From the primary cam chain tensioner the oil also branches to the rear piston jet to cool the underside of the rear piston. The final passages from the cam drive side main bearing routes oil back to the transmission and clutch where the oil lubricates and cools the transmission input and output shafts.
See Figure 3-3. Returning oil to the sump (19), the rear cylinder head drains onto the clutch (16) to lubricate primary gear and clutch assembly. Oil from the rear cylinder head also drains on the transmission input and output shaft gearset (16) where gear meshing transfers oil to all gears and then to the oil sump (17).
The oil in the front cylinder head drains down the cylinder head drain passage (18) to the sump (19).
Figure 3-1. Oil flow A: Red - hot oil; Blue - cooled oil; Light Blue - return oil
Figure 3-2. Oil flow В: Red - hot oil; Blue - cooled oil; Light Blue - return oil
Figure 3-2. Oil flow C: Red - hot oil; Blue - cooled oil; Light Blue - return oil