Passages in the cylinder case allow oil under pressure from the pump to move through a pipe/hose assembly to a cooler in the cooling system radiator (see Figure 3-4). The oil returns from the cooler through another pipe/hose assembly and enters the cylinder case again (see Figure 3-5).
If the difference in pressure between the oil entering and exiting the cooler system is greater than 9-11 psi, a valve in the cylinder case opens to allow oil to bypass the cooler system. This may occur during cold temperature operation when oil viscosity is high, or when a restriction exists in the cooler system.
