1. Engine Lubrication Systems
This presentation will explore:
Lubrication System Operation
Lubrication Components
Oil Distribution Systems

2. Lubrication System
The reservoir of oil is held in the sump (deep part of the oil pan).
Galleries
The oil is drawn into the engine through a pickup.
Oil is forced round the system by a pump.
Filter
The system is protected from over high pressure, by a pressure relief valve.
Particulates are strained out by a filter.
Sump
Pressure relief valve
Pickup
Pump
The oil is circulated around in galleries within the head and block.

3. Use of Oil
Oil acts as a hydrodynamic barrier between moving parts, to reduce friction and wear and remove heat from the working surfaces.
Oil film
Oil is usually refined from petroleum or crude oil, but there are many synthetic (man made) oils available.
For plain rotating bearings, the shaft diameter is made smaller (typically mm) than the bore diameter of
the bearing shell, to allow space for the oil film.
Crankshaft journal
Bearing shell
Oil film

4. Viscosity
Viscosity is the flow rate of oil, using the SAE (Society of Automotive Engineers) ratings, SAE 10, SAE 20, SAE 30, SAE 40, SAE 50. 30 10
Low viscosity (on the right) flows more easily, and is better for cold (starting) operation.
High viscosity is better when the engine is hot.
Most modern oils are mixtures of both, having multiviscosity (multiweight or multigrade), for example 10W30 to overcome the problems caused by the range of temperatures an engine may need to operate within.

5. Oiling Methods
Pressure-feed systems raise the oil to feed the upper parts of the engine.
Splash and drip-feed systems feed oil to the lower parts, returning surplus oil to the sump.

6. Lubrication System Components
Dipstick measures level of oil in the sump.
Sump bolts to the bottom of the cylinder block and holds the oil supply. It is sealed by a gasket.
Sump gasket
Sump
Oil filter mounted on cylinder block.
Oil Filter
Oil pump mounted to block.
Drain plug
Oil pickup links sump to oil pump.
Dip stick
Drain plug, to change oil.
Oil pump housing
Oil pickup

7. Rotary Oil Pump An inner rotor is driven by the pump shaft.
Outer rotor
Inner rotor
The inner rotor then drives an outer rotor.
A low-pressure region is created at the inlet, that draws oil in.
The rotation creates a high-pressure region at the outlet, forcing oil out and around the engine.
The rotor may be directly driven by a shaft, or may be gear or even chain driven.
Pump housing

8. Crankshaft-Driven Pump
Crankshaft splines
This pump is driven directly from splines on the crankshaft.
Main seal
Pump housing
These splines drive the inner gear (rotor).
Outer gear
The inner gear (rotor) drives the outer gear.
The pump housing is at the front of the engine in this design.
The pump insert holds the pump drive within the housing.
Inner gear
Pump insert

9. Gear Type Pump The pump shaft drives one of the gears.
Drive gear
The pump shaft drives one of the gears.
This turns the other gear in the opposite direction.
The turning of the gears produces low pressure at the inlet and high pressure at the outlet, forcing oil through the engine.
Driven gear

10. Oil Filter
They are usually a “spin-on” fitting with an O-ring seal to prevent leakage.
Fixing thread
O-ring
The outlet tube is at the centre.
Input feed holes
Several input feed holes are arranged directly into the filter element.
The paper element traps small metal, rust, carbon or dirt particles.
Paper element
Outlet tube
This keeps impurities out of the engine to prevent damage to working surfaces.

11. Oil pressure switch/sending unit
Oil Filter Housing
Oil pressure switch/sending unit
Bolts onto cylinder block
There may be a separate housing that bolts to the cylinder block for mounting the oil filter.
The oil pressure switch/sender unit may be mounted on this housing.
Some vehicles have oil cooling, and a cooler adapter or heat exchanger may be attached here.
Oil cooler
The oil filter is fitted onto the bottom, allowing oil to flow through both cooler and filter.
Oil filter
Heat shield
A heat shield may be used to keep engine heat away from the cooled oil.

12. Oil Cooler
Oil coolers are sometimes used to control engine oil temperature.
A heat exchanger similar to a radiator is used to transfer the heat to the outside air.
Hoses/pipes are usually connected to an adapter on the oil filter housing.
Oil coolers are normally only used for heavy-duty applications such as turbocharged engines or trailer towing vehicles.
Oil cooler
heat exchanger
Hoses/pipes

13. Galleries
Passages through the cylinder block and head called galleries carry oil to all parts of the engine.
Galleries
The engine shown has one camshaft and many valve train components, all needing lubrication.
Cylinders must be lubricated to allow the pistons to move freely up and down.
Galleries are used to carry oil to and from the oil filter.
A large diameter tube joins the pickup to the oil pump.