Mazda Training manual - part 247

 
5 – LUBRICATION SYSTEM 

 

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Oil Pan

 

 

Bolted onto the engine under the crankcase, the oil pan is a holding area   
— also called a reservoir or sump — for the engine oil. The oil pan transfers 
heat from the oil to the outside air, and it allows dirt picked up in the engine 
to settle out at the bottom. Many oil pans include a baffle to prevent oil from 
sloshing. 

 
 
 

Oil Strainer (Pick-Up)

 

 

The oil strainer or pick-up, is located in the bottom of the oil pan, where it is 
completely covered by the engine oil. The oil pump draws oil through the 
strainer. The oil strainer has a filter screen to keep large pieces of dirt and 
debris out of the circulating oil. 

 
 
 

Oil Pump

 

 

The oil pump provides the “push” that circulates the pressurized oil 
throughout the engine. 

 
 
 

Oil Filter

 

 

The oil filter traps smaller particles of metal, dirt, and debris carried by the oil 
so they don’t recirculate through the engine. The filter keeps the oil clean to 
reduce engine wear. 

 

Answers to 
Review 
Exercise 6

 

 
1.   valve 

clearance 
or lash 

2.   hydraulic 

lash 
adjuster 
(HLA) 

3.   pushrod 

4.   rocker arm 

5.   A, C 

 

 
5 – LUBRICATION SYSTEM 

 

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There are several other important parts of the lubrication system not shown in Figure 51. 
These are described below. 

 
 
 

Oil Seals

 

 

At various points in the engine, seals and gaskets are installed to prevent oil from leaking 
out of the engine or into places in the engine where oil should not be present. 

 
 
 

Dipstick

 

 

The engine oil dipstick is used to measure the level of oil in the oil pan. One end of the 
dipstick dips into the top of the oil reservoir, and the other end has a handle so it can be 
pulled out easily. The end that dips into the oil pan has a gauge on it that show whether oil 
should be added to the engine. 

 

It’s important to keep the oil level above the “ADD OIL” line at all times. 

The 

crankcase should never be overfilled or allowed to drop too low. Too much oil may permit 
the crankshaft to contact the oil and churn it until it turns to foam. The oil pump can’t pump 
foam, and foam will not lubricate. Low oil levels can result in excessively high oil 
temperatures, which may lead to bearing failure. An oil level that is too high or too low can 
also increase oil consumption. 

 

Consult the Workshop Manual or Owner’s Manual for the correct oil capacity and 
recommended oil. 

 
 
 

Oil Pressure Indicator

 

 

The instrument panel usually has some type of oil pressure indicator that warns the driver 
when the lubrication system cannot maintain the oil pressure needed by the engine. This 
indicator may be a gauge or a warning light. 
 

 

 
5 – LUBRICATION SYSTEM 

 

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HOW OIL CIRCULATES

 

 
Figure 52 shows how oil circulates through the lubrication system. The 
numbers in this figure match the numbered steps in the description that 
follows. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The oil in the oil pan is drawn up through the oil strainer by the oil 
pump. The strainer filters out large particles. 

 

Oil flows through the oil filter, which cleans the oil of smaller 
particles of dirt and debris. 

 

 
 
 
 
 
 

FIGURE 52. Oil 
circulates from 
the bottom of 
the oil pan up 
through the oil 
filter, into the 
cylinder block 
and cylinder 
head, through 
the crankcase, 
and back down 
into the oil pan. 

 

 

 
5 – LUBRICATION SYSTEM 

 

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From the oil filter, the oil flows into the main oil passage — or gallery  — in the 
cylinder block. 
 
From the main gallery, oil flows through smaller passages to the camshaft, pistons, 
crankshaft, and other moving parts. Oil holes and jets direct the flow of oil to critical 
parts, such as the bearings and pistons. 
 
As the oil lubricates the surfaces of moving parts, it is constantly pushed off by new oil, 
which cools the parts. The oil drips from the lubricated surfaces back into the oil pan. 
In the oil pan, the oil cools before being drawn back through the oil strainer to repeat 
the cycle. 

 
 
PRESSURE LUBRICATION

 

 
Full pressure is used to pump oil through the main oil gallery, which is a hollow passage 
cast into the cylinder block. Oil from the main gallery lubricates the crankshaft main 
bearings, connecting rod bearings, camshaft, and hydraulic lash adjusters (if equipped). 
 
In other parts of the engine, the volume is reduced as oil flows through smaller passages. 
The reduced volume ensures that the main bearings get enough oil and that excess oil is 
not introduced into the combustion chambers. The parts that are lubricated by reduced oil 
pressure include pushrod ends (in OHV engines) and rocker arms.