It should be noted that despite the real possibility of major repairs without removing the engine of such units as the connecting rod and piston group, this type of work usually cannot be performed as an independent operation. To repair the crank and other mechanisms, as a rule, some additional measures should be taken (for example, cleaning of parts and flushing of oil channels is mandatory). For this reason, such work is included in the list of basic engine overhaul procedures.
Engine Description
Engine 2.0 l (1998 cm/cube) belongs to the SR series installed on Nissan vehicles.
The engine is a 16-valve, overhead valve, four in-line cylinders and two camshafts. The engine is located transversely to the vehicle's axis, in the front part. The transmission is installed on the left side of the engine.
The crankshaft has 5 bearings. The axial clearance of the crankshaft is adjusted by selecting thrust half rings installed next to the upper liner of the middle (3rd) main bearing.
Connecting rod bearings consist of two liners inserted into the connecting rod and into the connecting rod cap parallel to the crankshaft axis. The connecting rods are connected to the pistons using pins that are installed with tension in the connecting rod head and secured in the piston with spring retaining rings. The pistons are cast from aluminum alloy, there are three rings on the pistons - two compression rings and one oil scraper ring.
The cylinder block is cast from cast iron, the cylinders are bored inside the block. On engines of the type under consideration, the cylinder bores are sometimes called "dry liners".
The intake and exhaust valves are closed by coil springs and move inside guide bushings pressed into the cylinder head together with the valve seats. In case of increased wear, the seats and bushings can be pressed out independently of each other and replaced with new ones.
[The text was copied from the portal: www.NISSANBOOK.ru]
The camshafts are chain-driven and control 16 valves via levers. The levers are mounted directly under the camshafts. Valve clearances are adjusted automatically using hydraulic devices. The lower bearings of the camshaft journals are beds bored into the cylinder head bosses.
An oil pump driven by the crankshaft nose is used to lubricate the engine. Oil passes through an oil receiver with a coarse filter and through a fine filter screwed into the cylinder block, from which it is directed through lubrication channels inside the cylinder block and crankcase to the crankshaft main bearings and to the camshaft bearing journals. The connecting rod bearings are lubricated under pressure through holes inside the crankshaft, and the camshaft bearing journals are also lubricated under pressure. The camshaft cams, valve stems and other engine parts are lubricated by splashing. Some models are equipped with an oil cooler designed to maintain the oil temperature at a constant level under extreme engine operating conditions.