The Chevrolet Niva family of cars (VAZ-2123) are equipped with 4-cylinder engines with in-line vertical cylinders and an overhead camshaft, equipped with a distributed fuel injection system.
The VAZ-2123 engine was developed on the basis of the VAZ-21214 engine, which, in turn, is a modernized VAZ-21213 engine and meets the Euro II toxicity standards.
The main difference between these engines and their predecessor is in the design of the valve timing mechanism - a single-row chain and a hydraulic chain tensioner are used to reduce noise.
Hydraulic valve supports are installed for the same purpose, an additional difference is a boss on the cylinder block for installing a knock sensor.
The VAZ-21213 engine was equipped with a central injection system, which did not have a detonation suppression function.
The VAZ-2123 engine has a design that is almost identical to the VAZ-21214 engine of the Niva VAZ-21214 car.
The main difference is in the shape of the intake tract and in the location of the front supports of the power unit - in the VAZ-2123 engine they are installed exactly on the line of the center of gravity, unlike previous engines installed on supports cantilever.
The engine cylinders are numbered from the crankshaft pulley.
On the left side of the cylinder head, near its lower plane, the number of each cylinder is cast, as well as the firing order of the cylinders (1-3-4-2).
The engine cylinders are combined together with the upper part of the crankcase into a single cast iron casting - a block of 17 cylinders.
A crankshaft 3, cast from cast iron, is mounted on five supports in the lower part of the cylinder block.
Thin-walled bimetallic steel-aluminum liners are used as crankshaft support bearings, as well as connecting rod journal bearings.
The front and rear ends of the crankshaft are sealed with self-tightening rubber oil seals.
Each engine cylinder has one intake and one exhaust valve.
The exhaust valves are welded from two parts: a rod made of chromium-nickel-molybdenum steel, a plate made of chromium-nickel-manganese steel with a working chamfer welded with a special heat-resistant alloy.
The intake valves are made of chromium-nickel-molybdenum steel.
The stems of all valves are nitrided, and the ends of the rods are hardened by high-frequency currents.
The valves move in the guide bushings under the action of the camshaft cams through steel levers 3, resting with one shoulder on the spherical heads of hydraulic supports 6, the other - on the ends of the valve stems 2.
The hydraulic bearings are screwed into the sockets of the head 1 of the block.
Oil under pressure is supplied to the hydraulic bearings through a separate tube 4 of the ramp from the hole in the camshaft bearing housing near the middle stud of its fastening.
Since there are practically no gaps in the valve mechanism, the pressure springs of the levers used in the VAZ-21213 engine are excluded.
Pistons 10 are cast from aluminum alloy and coated with a layer of tin to improve running-in.
The piston skirts have a complex geometric shape: conical in height, with a large base at the bottom of the skirt, and oval in cross section, with a larger axis located perpendicular to the axis of the piston pin.
The axes of the holes for the piston pins are offset from the axis of symmetry of the pistons by 1.2 mm to the right side of the engine.
Two compression rings and one oil scraper ring are installed in the piston grooves.
The groove of the oil scraper ring has through holes through which the oil collected by the ring is supplied into the piston to lubricate the piston pin.
With forged steel connecting rods 23 pistons are connected by means of steel case-hardened piston pins of tubular section.
Piston pins of floating type rotate freely in the upper bosses of the connecting rod and in the bosses of the pistons.
Piston pins are fixed from axial movement by spring rings located in the grooves of the bosses of the pistons.
Camshaft 15 is cast iron, cast, with whitened rubbing surfaces of cams, installed in a removable aluminum housing, fixed on the upper plane of the cylinder head 8, cast from aluminum alloy.
It is driven from the crankshaft by a single-row roller chain 7. The same chain drives the oil pump drive shaft.
The number of teeth of the sprocket of the oil pump drive shaft is reduced in comparison with the VAZ-21213 engine from 38 up to 30 in order to increase the oil pump feed.
The chain is kept taut by a spring-hydraulic tensioner through a plastic shoe, the dimensions of which are significantly increased compared to the shoe of the VAZ-21213 engine. Before starting the engine, the chain is pre-tensioned by spring 7, and after starting - by oil pressure supplied through a steel tube from an adapter under the emergency oil pressure drop sensor.
Oil from the lubrication system enters cavity (E) of the tensioner under pressure through tube 4, then through hole (D) and valve unit 2 enters cavity (B), where it acts on plunger 5.
A drainage hole with a diameter of 1 mm is made in the housing 1 of the tensioner to release air from cavity (E).
Chain vibrations are damped by a damper, as well as a tensioner shoe made of wear-resistant plastics.
The cylinder head is attached to the block with eleven bolts and centered on it with two bushings.
A disposable gasket made of shrink-resistant material is installed between the head and the block.
The top of the cylinder head is closed with a stamped steel cover 14, under which a sealing gasket made of a rubber-cork mixture is installed.
The oil pan 1 is attached to the lower part of the cylinder block through a rubber-cork gasket, closing the cavity of the block from below and acting as a reservoir for oil.
The lubrication system is combined: under pressure and splash.
The main and connecting rod bearings, camshaft drive bearings and oil pump drive shaft, camshaft cams and oil pump drive gear bushings are lubricated under pressure.
The oil flowing out of the gaps and splashed by the moving parts lubricates the cylinder walls, pistons with piston rings, piston pins, timing chain, ball heads of the valve drive hydraulic bearings, as well as the valve stems and their guide bushings.
The system consists of an oil sump 1, a gear oil pump 15 with a built-in pressure-reducing valve and an oil receiver with a coarse mesh filter for oil purification, a full-flow filter 13 for fine oil purification with a bypass and anti-drain valves, a sensor for a warning lamp for insufficient oil pressure and oil channels.
The crankcase ventilation system is closed, with crankcase gases being discharged through the oil separator 6 into the intake pipe, then the crankcase gases are directed into the engine cylinders, where they are burned.
When the engine is idling, crankcase gases enter through hose 2 of the first circuit through a calibrated hole (jet) in the throttle body.
In this mode, a high vacuum is created in the intake pipe and crankcase gases are effectively sucked into the throttle space.
The jet limits the volume of gases sucked out so that the engine operation at idle is not disrupted.
When the engine is running under load, when the throttle valve is partially or fully open, the main volume of gases passes through hose 3 of the second circuit into the air supply pipe 4 in front of throttle assembly and further into the intake pipe and combustion chambers.
The engine cooling system consists of a cooling jacket made of casting and surrounding the cylinders in the block, combustion chambers and gas channels in the cylinder head and intake pipe.
Forced circulation of liquid in the system is provided by a centrifugal water pump driven by the crankshaft using a V-belt, which also serves as a generator drive.
To maintain the normal operating temperature of the coolant, a thermostat is installed in the cooling system, blocking a large circle of the system when the engine is not warmed up and the coolant temperature is low.
The engine fuel system consists of an electric fuel pump installed in the fuel tank, a throttle assembly, a fine fuel filter, a fuel pressure regulator, injectors and fuel hoses.
The ignition system consists of an ignition module mounted on a special bracket on the block cylinders, spark plugs and high-tension wires.
The ignition system is controlled by the engine control unit (ECU).