Lubrication system (Discovery 3)

Lubrication system

NOTE: Oil cooler version shown.

The lubrication system provides filtration of the entire oil flow and supply of oil under pressure.
From the oil pan, the oil flows through a mesh filter and an oil inlet pipe into the oil pump, which is driven by the intermediate shaft and has a built-in oil relief valve. The mesh filter and oil inlet pipe prevent foreign particles from passing through the oil pump, thereby protecting it from damage and preventing clogging of the oil channels. The oil relief valve in the oil pump opens when the oil pressure becomes too high and diverts the oil back around the pump.

Oil is supplied under pressure by the pump through an oil filter mounted on the oil pump housing. The lubrication system is designed in such a way that most of the oil flow is directed to the main oil gallery of the cylinder block, and a smaller part (determined by the limiter in the oil filter housing) - in the oil cooler (if available). The remaining oil flow from the outside of the oil filter is combined with the return flow from the oil cooler. (if available), and then fed into the main oil gallery of the cylinder block.



The main oil gallery has passages through which oil is supplied to each cylinder head and main bearings. Cross-drilled holes in the crankshaft main bearings supply oil to the connecting rod lower-end bearings. Oil galleries in the cylinder head supply oil to the camshafts and hydraulic lash adjusters.

An oil pressure sensor is installed in the cylinder block, which determines the oil pressure before it is supplied to the main gallery of the cylinder block. When low oil pressure is registered, a control lamp on the instrument panel comes on.

Oil under reduced pressure is supplied to each bank of cylinders through two cylinder block stops/cylinder head dowel pins, one at the front of the left bank and one at the rear of the right bank. The oil then flows through a passage in the cylinder head bore into the camshaft housing and is supplied through separate holes to the camshaft bearings and hydraulic tappet housings. Return oil from the cylinder head drains into the oil sump through the cylinder head bolt passages.

Oil dipstick

Item name	Spare part catalog number	Description
1	-	Oil dipstick
2	-	Oil dipstick tube

The oil dipstick is located on the left side of the cylinder block in a tube inserted into the oil pan. The two holes at the end of the dipstick correspond to the minimum and maximum oil levels. The difference between these two marks is approximately 1.5 liters.