C13 On-Highway Engines Caterpillar

• Control group for the CGI system

• Control group for the combustion air system

Illustration 1	g02038439
Lubrication system schematic (1) Oil flow to variable valve actuators (2) Warm up valve (3) Piston cooling jets (4) Main oil gallery in cylinder block (5) Engine oil pressure sensor (6) Oil flow to valve mechanism and Cat compression brake (if equipped) (7) Camshaft journals (8) Oil filter bypass valve (9) Main bearings (10) Signal line (11) Primary engine oil filter (one or two filters) (12) Engine oil pump (13) Oil cooler bypass valve (14) Engine oil cooler (15) Oil pan sump (16) High-pressure relief valve and oil pump bypass valve

Illustration 2	g01782513
Right side view of engine (11) Primary engine oil filter (one or two filters) (12) Engine oil pump (14) Engine oil cooler

The lubrication system supplies filtered oil at a temperature below 110 °C (230 °F) and at a pressure above 275 kPa (40 psi) at rated engine operating conditions. Oil pump bypass valve (17) is controlled by the engine oil manifold pressure, rather than the oil pump pressure. The engine oil manifold pressure is independent of the pressure drop that is caused by the engine oil filter and the engine oil cooler.

Oil cooler (14) maintains an engine oil temperature that is below 110 °C (230 °F). High-pressure relief valve (16), which is located in the filter base, protects the filters and other components during cold starts. The opening pressure of the high-pressure relief valve is 679.77 kPa (99 psi). The opening pressure of the oil filter bypass valve is a pressure differential of 170 kPa (25 psi). Engine oil pressure sensor (5) is part of the engine protection system.

The turbocharger cartridge bearings are lubricated by the oil supply line from the main oil gallery, and the oil drain line returns the oil flow to the sump.

Oil Flow Through The Lubrication System

Illustration 3	g01799353
(8) Engine oil filter bypass valve (13) Cooler bypass valve (18) Oil filter base

The engine oil pump is mounted to the back of the front gear train on the lower right-hand side of the engine. The engine oil pump is driven by an idler gear from the crankshaft gear. Oil is pulled from the sump through oil pump bypass valve (17) on the way to the engine oil cooler. The bypass valve controls the oil pressure from the engine oil pump. The engine oil pump can supply excess oil for the lubricating system. When this situation is present, the oil pressure increases forcing the bypass valve to open. The open bypass valve allows the excess oil to return to the sump.

High-pressure relief valve (16) regulates high pressure in the system. The high-pressure relief valve will allow the oil to return to the sump when the oil pressure reaches 680 kPa (98 psi). The fully open pressure for the high-pressure relief valve is 695 kPa (100 psi). The oil then flows through the engine oil cooler. The engine oil cooler uses engine coolant in order to cool the oil. The oil cooler bypass valve (13) directs the oil flow through the engine oil cooler by two different methods.

Oil cooler bypass valve (13) will open when the oil pressure exceeds a pressure differential of 196 kPa (28 psi). Opening of the bypass valve will bypass the oil through the engine oil cooler. The bypass valve is fully open when the engine oil pressure reaches a pressure differential of 202 kPa (29 psi). This open bypass valve will allow engine oil to bypass the engine oil cooler.

Approximately 5 percent of the oil flow is directed through an orificed passage that leads to the second oil filter (if equipped). The oil flows through the bypass filter and to the engine oil sump. The main oil flow now flows toward the primary engine oil filter. The valve is fully open when the oil pressure differential across oil filter bypass valve (8) reaches 196 kPa (28 psi). This open bypass valve will allow the oil flow to bypass the primary engine oil filter. Then, the engine oil will lubricate the engine parts. The bypass valve provides immediate lubrication to the engine components when there is a restriction in the primary engine oil filter due to the following conditions:

• Cold oil with high viscosity

• Plugged primary engine oil filter

Note: Refer to Specifications, "Engine Oil Filter Base" for a cross section of the valves in the engine oil filter base.

Illustration 4	g01788133
Interior of cylinder block (19) Piston cooling jet (20) Piston (21) Connecting rod

Filtered oil flows through main oil gallery (4) in the cylinder block to the following components:

• Piston cooling jets (18)

• Valve mechanism

• Camshaft bearings

• Crankshaft main bearings

• Turbocharger

The piston cooling jets provide the underside of the piston with liberal amounts of oil. The oil is used to remove heat from the piston. The oil is also used as a lubricant.

The breather allows engine blowby to escape from the crankcase. The engine blowby is discharged into the atmosphere through a hose. The discharged blowby prevents pressure from building up that could cause seals or gaskets to leak.