What by-pass or relief valves are in the lubrication circuit?

A regulator valve at the oil pump and an oil filter relief valve that by-passes the oil filter.

Where is the oil pressure switch located in the circuit?

The oil pressure switch is connected to the main oil gallery.

What do the different arrow symbols in the diagram mean?

Per the legend: an open arrow is an oil passage, a shaded arrow is an oil gallery in the cylinder block, and a dashed arrow is a by-pass passage.

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Nissan Micra Engine Lubrication System - Oil Circuit Flow Diagram (LC-2)

Engine lubrication circuit schematic with oil flow diagram and cutaway engine

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Engine lubrication circuit schematic showing oil flow paths through pump, filter, and galleries.

AI caption April 2005 · Photo 92 of 412

This document is a page (LC-2) from a service manual section titled "ENGINE LUBRICATION SYSTEM — Lubrication Circuit." It contains two elements: a cutaway line drawing of a 4-cylinder engine with arrows tracing oil flow through the camshaft, rocker gear, pistons, crankshaft, timing chain area, and oil pan pickup; and a schematic flow diagram of the lubrication circuit. The flow diagram shows oil drawn from the oil pan through the oil strainer to the oil pump, then through the oil filter to the main oil gallery, with a regulator valve and an oil filter relief valve providing by-pass paths, and an oil pressure switch connected to the main oil gallery. From the main oil gallery, one branch feeds the cylinder head bolt (center), camshaft center bearing, rocker shaft, cam, camshaft front & rear bearings, and oil pump drive shaft; the other branch feeds the main bearings, crankshaft, connecting rod bearings, and piston/cylinder walls, all returning to the oil pan. A legend distinguishes oil passages, oil galleries in the cylinder block, and by-pass passages. Readers can learn the complete oil routing and pressure-relief scheme for this engine. Page reference codes: SLC4 and LC-2.

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Frequently asked questions

What path does the oil take from the oil pan back to the engine?: Oil flows from the oil pan through the oil strainer to the oil pump, then through the oil filter to the main oil gallery.
What components does the main oil gallery feed?: It feeds two branches: one to the cylinder head bolt (center), camshaft center bearing, rocker shaft, cam, camshaft front & rear bearings and oil pump drive shaft; the other to the main bearings, crankshaft, connecting rod bearings, and piston and cylinder walls. All oil returns to the oil pan.
What by-pass or relief valves are in the lubrication circuit?: A regulator valve at the oil pump and an oil filter relief valve that by-passes the oil filter.
Where is the oil pressure switch located in the circuit?: The oil pressure switch is connected to the main oil gallery.
What do the different arrow symbols in the diagram mean?: Per the legend: an open arrow is an oil passage, a shaded arrow is an oil gallery in the cylinder block, and a dashed arrow is a by-pass passage.