The main caterpillar lubricating oil system is illustrated in figure 8-10. Under normal operating conditions, lubricant from the oil pan base is pumped through the oil cooler, through the filter housing, and to the lube oil distribution gallery. A pressure-regulating valve (A) mounted on the oil pan base limits the maximum value of oil pressure. Bypass valves (B) in each filter housing divert the oil to the oil distribution gallery whenever the flow is momentarily restricted because of cold oil. When the oil is warm, only filtered oil is furnished to the engine bearings unless the oil filter elements become restricted. If the filter should become restricted, the bypass valves would open and the oil would flow directly to the lube oil distribution gallery. The lube oil distribution gallery would then direct the oil through the connecting passages to the internal and external components of the engine, the timing gear, and the front accessory drive.

External Components

In the lubrication of the external components of the Caterpillar diesel engine, the turbocharger governor, fuel injection pump housing, and fuel pump driveshaft receive lubricant from the fuel pump and governor drive housing oil manifold. (See fig. 8-10.) Any drain-back oil from these components returns to the oil pan base.

Internal Components

In the lubrication of the internal components, the oil distribution manifold directs the filtered lubricant through passages and tubes to the piston oil spray orifices, valve rocker mechanism, cam-shaft bearings, crankshaft bearings, connecting rod bearings, fuel pump, and governor drive housing oil manifold.

In the lubrication of the timing gear mechanism, the timing gears are lubricated by the drain-back of oil from the turbocharger, cam-shaft, and crankshaft. Oil, under pressure, also flows to the camshaft bearings.

In the lubrication of the front accessory drive, the oil distribution manifold delivers oil through a drilled passage to the front main bearing and the front accessory drive.

The information provided in this section is intended to show you that a lubrication system for any engine is an intricate system that must not only supply oil to the components but also supply the correct flow rate of oil at the specified temperature and pressure. The information and illustrations in this section have been provided as examples only. Whenever you need information about a specific diesel engine, you should refer to the NAVSEA technical manual for your engine.