Engine Lubrication: Description and Operation

Lubrication System - Low-Pressure









Low-Pressure Oil Flow
The lubrication system is comprised of a low-pressure system and a high-pressure system. The low-pressure system provides primary engine lubrication while the high-pressure system provides the hydraulic pressure required to actuate the fuel injectors.

The low-pressure lubricating system draws oil from the engine oil pan through the oil pump screen cover and tube into the oil inlet passage in the front cover. The gerotor oil pump then pumps the oil back out through the outlet passage in the front cover. The oil separates into two paths.

One flow path sends oil into the high-pressure pump reservoir initial fill gallery (integral to the cylinder block) and through the anti-drainback check ball. During cold start the oil feeds in two directions from the anti-drainback check ball. One feed leaves the check ball and enters the front cover. From there it enters the high-pressure oil reservoir. The second feed exits the check ball and enters the left bank valve lifter oil gallery.

After leaving the front cover outlet passage, the second oil path sends the oil through the oil cooler and filter assembly. Once inside the filter housing, the oil filter bypass valve may open to vent excess pressure and oil back into the oil pan. After the oil has been circulated through the oil filter, the oil feed then enters the main oil gallery (integral to the cylinder block). Once in the main oil gallery, the oil is routed to the five crankshaft main bearings through five drilled and machined feed galleries (integral to the cylinder block). The five camshaft bearings receive the oil feed through five vertically drilled and machined feed galleries connected to the main bearing feed galleries. The front main bearing feed gallery also supplies oil to the right bank valve lifter oil gallery through a vertically drilled and machined oil feed gallery (integral to the cylinder block). The rear main bearing oil feed gallery also supplies oil to the turbocharger assembly through a vertically drilled and machined oil feed gallery (integral to the cylinder block).

Pressurized oil entering the turbocharger assembly is utilized to lubricate the compressor/turbine shaft. The oil drains back through the turbocharger mounting pedestal and back into the oil pan. The valve lifter oil gallery supplies pressurized oil to the valve tappets and to the piston cooling oil jets. Oil from the valve tappets is routed upward to the cylinder head valve train through hollow push rods. Once in the cylinder head, the oil drains back to the oil pan through return ports at each end of the cylinder head.

Lubrication System - High-Pressure





High-Pressure Oil Flow
During initial start or cold start, the high-pressure oil pump receives unfiltered oil from the left side valve lifter oil gallery through the anti-drain back check ball valve. Once the engine starts or during warm engine starts, the check ball closes and the high-pressure oil pump receives filtered oil from the high-pressure oil pump reservoir. The high-pressure oil pump pumps the oil under extremely high pressures (4,115 - 20,577 kPa) through the left and right side high-pressure supply hoses to the high-pressure oil rails (integral to the cylinder heads). Once in the oil rail, the oil is fed to the fuel injector bores through four oil feed galleries drilled and machined in the cylinder head. The high-pressure oil then actuates the fuel injectors.