Figure 6-20.Oil level gauge.
holds a supply of oil for the lubrication system. The oil
pan is fitted with a screw-in drain plug for oil changes.
Baffles may be used to keep the oil from splashing
around in the pan.
The sump is the lowest area in the oil pan where oil
collects. As oil drains from the engine, it fills the sump.
Then the oil pump can pull oil out of the pan for
Oil Level Gauge
The oil level gauge, also known as a dipstick, is
usually of the bayonet type (fig. 6-20). It consists of a
long rod or blade that extends into the oil pan. It is
marked to show the level of oil within the oil pan.
Readings are taken by pulling the rod out from its
normal place in the crankcase, wiping it clean, replacing
it, and again removing and noting the height of the oil on
the lower or marked end. This should be done with the
engine stopped unless the manufacturer recommends
otherwise. It is important that the oil level not drop
below the LOW mark or rise above the FULL mark.
The oil pump is the heart of the lubricating system;
it forces oil out of the oil pan, through the oil filter,
galleries, and to the engine bearings. Normally, a gear
on the engine camshaft drives the oil pump; however, a
cogged belt or a direct connection with the end of the
camshaft or crankshaft drives the pump in some cases.
There are two basic types of oil pumpsrotary and
The ROTARY pump (fig. 6-21) has an inner rotor
with lobes that match similar shaped depressions in the
Figure 6-21.Rotor-type oil pump.