LUBRICATION SYSTEM - Continued
Figure 12. Oil Pump Pressure Regulator.
Oil leaving the pump under pressure passes into the pressure relief valve body. The spring-loaded valve opens
when the pressure exceeds approximately 105 PSI (724 kPa) and directs the excess oil to the oil pan. The
pressure relief valve is located at the lower end of the vertical oil gallery near the front of the cylinder block on the
oil cooler side. The pressure relief valve consists of a valve body, a hollow piston-type valve, a spring, spring seat,
and a pin to retain the valve assembly within the valve body. The relief valve assembly used on the 8V engines is
composed of the same parts as the regulator valve assembly. However, the retaining pin is located in the inner
pin hole in the valve body to provide the necessary tension on the spring.
Service operations for the pressure relief valve are similar to those of the regulator valve. The spring in the 8V
relief valve assemblies is the same as used in the oil pressure regulator assemblies. Replace the springs when
they are pitted or fractured.
Engine Oil Cooler
In order to perform its functions satisfactorily, the lubricating oil must be kept within the proper temperature limits.
If the oil is too cold, it will not flow freely. If the oil is too hot, it cannot support the bearing loads, it cannot carry
away enough heat, and it may result in too great an oil flow. As a consequence, oil pressure may drop below
acceptable limits and oil consumption may become excessive. In performing its lubricating and cooling functions,
the oil absorbs a considerable amount of heat and this heat must be dissipated by an oil cooler. Each engine is
provided with an oil cooler mounted on the right-hand side of the cylinder block at the lower front corner as viewed
from the flywheel end of the engine. The 8V turbocharged engines are equipped with a 24 plate oil cooler. Oil
from the lubricating oil pump flows through a passage in the oil cooler adapter to the oil filter, then through the oil
cooler, where it is cooled by engine coolant and finally through the outlet passage in the cooler adapter which
leads to the cylinder block oil galleries. The engine coolant is pumped through the oil cooler and completely
surrounds the oil cooler core. To ensure continuing engine lubrication should the oil cooler become plugged, a
bypass valve is installed in the oil cooler adapter.