885171 Mercruiser STUD

Illustration 1 g02793645
(1) Rocker Arm
(2) Oil Pressure Switch
(3) Rocker Arm Shaft
(4) Push Rod
(5) Tappet
(6) Camshaft
(7) Fuel Injection Pump
(8) Piston
(9) Connecting Rod
(10) Oil Cooler
(11) Oil Filter Cartridge
(12) Relief Valve
(13) Oil Strainer
(14) Oil Pump
(15) Crankshaft
(16) Idler Gear
(17) Governor Shaft
(18) Valve This lubrication system consists of an oil strainer (13), oil pump (14), relief valve (12), oil filter cartridge (11), oil cooler (10), and oil pressure switch (2).The oil pump sucks lubricating oil from the oil pan through the oil strainer and the oil flows down to the oil filter, cartridge where it is further filtered. Then the oil is forced to crankshaft (15), connecting rods (9), idler gear (16), governor shaft (17), camshaft (6), rocker arm shaft (3), and fuel injection pump (7) to lubricate each part through the oil gallery.Some part of oil, splashed by the crankshaft or leaking and dropping from gaps of each part, lubricates following parts.
Pistons
Cylinder walls
Small ends of connecting rods
Tappets
Push rods
Intake and exhaust valves
Timing gearsOil Pump
Illustration 2 g03400120
(19) Inner rotor
(20) Outer rotor
(21) Inlet port
(22) Outlet port This oil pump has an inner rotor (19) and an outer rotor (20).The inner rotor, which is driven by crankshaft, rotates the outer rotor in the same direction.The inner rotor has one less lobe than the outer rotor, and the rotors are eccentrically engaged with each other.This allows the other lobes to slide over the outer lobes, making a seal to prevent back-up of oil. As the lobes slide up and over the lobes on the outer rotor, oil is drawn in. As the lobes fall into the outer rotors cavities, oil is squeezed out.This oil pump has two gears in mesh, closely fitted inside a housing. The drive shaft drives one gear, which in turn drives the other gear.As the gears rotate and come out of mesh, the gears trap inlet oil between the gear teeth and housing. The trapped oil is carried around to the outlet port (22). As the gears mesh again, the gears form a seal which prevents oil from backing up to the inlet port (21). The oil is forced out at the outlet port and sent each part through the oil gallery.Relief Valve
Illustration 3 g02793852
Ball Type Direct Acting Relief Valve
(23) Spring
(24) Ball
(25) Valve Seat The relief valve prevents the damage of the lubricating system due to high oil pressure.These engines have a ball type direct acting relief valve. These valves are best suited for low pressure.The valve is closed when the spring (23) tension is greater than the oil pressure at the inlet. The spring tension holds the ball (or poppet) (24) securely in position.The valve opens when the oil pressure at the inlet exceeds that of the spring. This pushes the ball (or poppet) off the inlet hole and oil flows through the valveOil Filter Cartridge
Illustration 4 g02793875
Bypass Valve Closed
(A) Filtered Oil
(B) Unfiltered Oil
(26) Oil Filter Element
Illustration 5 g02793878
Bypass Valve Open
(B) Unfiltered Oil
(27) Oil Filter Element
(28) Oil Filter Bypass Valve These engines have filtration system of full flow.In the full filtration system, there is only one oil flow from the oil pump to the oil filter cartridge. After filtering, the oil goes to the lubricating portion, and is returned to the crankcase.When the filter cartridge is new, there is little pressure drop through the filter element. However, if the filter gets clogged, the resulting pressure will open the bypass valve (28) and allow unfiltered oil to bypass to the lubricating portion.