Figure 1-8. Engine Coolant System Components
Lubricating System. The engine lubricating system (Figure 1-9) is designed to provide adequate lubrication
to engine components to ensure smooth operation. The engine uses a gerotor type oil pump to draw oil from the oil pan,
through an oil suction connection, and onto the oil cooler.
The forklift engine uses a full flow, plate type oil cooler. Oil flows through a cast passage in the cooler cover
and through an element. The oil is cooled by engine coolant flowing past the plates of the element. The four cylinder
engine uses an element with five plates.
After oil is cooled, it flows through a full flow oil filter. The oil cooler contains a bypass valve that will let oil
flow bypass a plugged filter. The valve is designed to open when pressure drop across the filter is more than 138 kPa (20
PSI), as with a plugged filter. When a filter becomes plugged, an oil pressure decrease of 60 kPa (10 PSI) or less from
the normal operating pressure can be observed on the vehicle oil pressure gauge.
A pressure relief valve is designed to keep oil pressure from exceeding 414 kPa (60 PSI). When oil pressure
from the pump is greater than 414 kPa (60 SPI), the relief valve opens uncovering the dump port so part of the oil is routed
back to the oil pan.