The K4M engine is a petrol, four-stroke, four-cylinder, in-line, sixteen-valve engine with two overhead camshafts.
Firing order of the cylinders: 1—3—4—2, counting from the flywheel.
Fuel system: distributed fuel injection (Euro 4 emission standards).
The engine, gearbox and clutch form the power unit — a single assembly mounted in the engine compartment on three elastic rubber-metal mountings.
The right mounting is attached to the upper cover of the timing drive, while the left and rear mountings are attached to the gearbox housing.
At the front of the engine (in the direction of vehicle travel) are located: the intake pipe; the oil filter; the oil level dipstick; the low oil pressure warning sensor; the fuel rail with injectors; the knock sensor; the coolant pump supply pipe; the alternator; the power steering pump; the air conditioning compressor.
At the rear of the engine are located:
- the air filter housing with the idle speed control valve;
- the exhaust manifold with the control oxygen sensor;
- the starter motor.
On the right — the coolant pump; the timing drive and coolant pump drive (toothed belt); the auxiliary drive (poly-V belt).
On the left are located: the flywheel; the crankshaft position sensor; the thermostat; the thermostat housing with the coolant temperature sensor.
On top — the ignition coils and spark plugs; the oil filler neck; the receiver with the absolute pressure and intake air temperature sensors, the throttle body with the throttle position sensor.
The engine cylinder block is cast from cast iron, the cylinders are bored directly in the block.
In the lower part of the cylinder block are five main bearing supports of the crankshaft with removable caps, secured to the block by special bolts.
The holes in the cylinder block for the bearings are machined with the caps fitted, so the caps are not interchangeable and are marked on their outer surface for identification (the caps are numbered from the flywheel side).
On the end faces of the middle support are recesses for the thrust half-washers, which prevent axial movement of the crankshaft.
To cool the pistons during engine operation, their crowns are sprayed from below with engine oil through special nozzles pressed into the cylinder block in the area of the second and fourth main bearing supports (on both sides of the supports).
Crankshaft with five main and four big-end journals.
The main and big-end bearing shells of the crankshaft are steel, thin-walled with an anti-friction coating applied to the working surfaces of the shells.
The shaft is provided with four counterweights made integral with the shaft.
To supply oil from the main journals to the big-end journals, channels are made in the journals and webs of the shaft.
On the front end (nose) of the crankshaft are mounted: the oil pump drive sprocket, the timing drive toothed pulley and the auxiliary drive pulley.
The toothed pulley is secured on the shaft by a lug which enters a slot on the nose of the crankshaft.
The auxiliary drive pulley is secured on the shaft in a similar way.
The crankshaft is sealed by two oil seals, one of which (on the timing drive side) is pressed into the cylinder block cover, and the other (on the flywheel side) — into a recess formed by the surfaces of the cylinder block and the main bearing cap.
The flywheel is attached to the crankshaft flange by seven bolts.
It is cast from cast iron and has a pressed-on steel ring gear for starting the engine with the starter. In addition, a toothed ring gear for the crankshaft position sensor is cut on the flywheel.
The connecting rods are forged steel, of I-section, and are machined together with their caps.
The caps are secured to the connecting rods by special bolts with nuts.
By their lower (crank) eyes the connecting rods are connected through the bearing shells to the big-end journals of the crankshaft, and by their upper eyes — through the piston pins — to the pistons.
The piston pins are steel, of tubular section.
The pin, pressed into the connecting rod upper eye, rotates freely in the piston bosses.
The pistons are made of aluminium alloy.
The piston skirt has a complex shape: barrel-shaped in longitudinal section and oval in cross-section.
In the upper part of the piston three grooves for the piston rings are machined.
The two upper piston rings are compression rings, and the lower one is the oil control ring.
The cylinder head is cast from aluminium alloy and is common to all four cylinders.
The cylinder head is centred on the block by two bushes and secured by ten bolts.
A non-settling metal gasket is fitted between the block and the head.
On opposite sides of the cylinder head are the windows of the inlet and exhaust ports.
The spark plugs are fitted in the centre of each combustion chamber.
The valves are steel and are arranged in the cylinder head in two rows, in a V, with two inlet and two exhaust valves per cylinder.
The inlet valve head is larger than the exhaust valve head.
The valve seats and guides are pressed into the cylinder head.
Valve stem seals are fitted over the valve guides.
The valve closes under the action of the spring.
At its lower end the spring rests on a washer, and at its upper end — on a retainer held by two collets.
The assembled collets are tapered on the outside and are provided on the inside with thrust shoulders which enter the groove on the valve stem.
Two camshafts are mounted in the upper part of the cylinder head.
One shaft operates the inlet valves of the timing gear, and the other — the exhaust valves.
Eight cams are made on each shaft — an adjacent pair of cams simultaneously operates the valves (inlet or exhaust) of each cylinder.
A design feature of the camshaft is that the cams are pressed onto a tubular shaft.
The camshaft supports (bearings) (six supports for each shaft) are split — they are located in the cylinder head and in the cylinder head cover.
The camshafts are driven by a toothed belt from the crankshaft pulley.
On each camshaft, on the toothed pulley side, a thrust flange is made which, on assembly, enters the groove of the cylinder head, thereby preventing axial movement of the shaft.
The camshaft pulley is secured on the shaft not by a tight fit, key or pin, but only by the friction forces arising on the end surfaces of the pulley and the shaft when the pulley securing nut is tightened.
The camshaft nose is sealed by an oil seal fitted over the shaft journal and pressed into a recess formed by the surfaces of the cylinder head and the cylinder head cover.
The valves are operated from the camshaft cams through valve rocker arms.
To increase the service life of the camshaft and valve rocker arms, the shaft cam acts on the rocker arm through a roller rotating on the rocker arm axis.
The hydraulic tappets of the valve rocker arms are installed in the recesses of the cylinder head.
Oil enters the hydraulic tappet from the gallery in the cylinder head through a hole in the hydraulic tappet body.
The hydraulic tappet automatically ensures clearance-free contact between the camshaft cam and the rocker arm roller, compensating for wear of the cam, the rocker arm, the end of the valve stem, the seat and valve head chamfers.
Engine lubrication is combined.
Under pressure, oil is supplied to the main and big-end bearings of the crankshaft, the camshaft bearings and the hydraulic tappets of the valve rocker arms.
Other engine components are lubricated by splashing.
The pressure in the lubrication system is created by a gear-type oil pump located in the oil sump and attached to the cylinder block.
The oil pump is driven by a chain drive from the crankshaft.
The driving sprocket of the pump drive is mounted on the crankshaft under the cylinder block cover.
A cylindrical band is made on the sprocket, on which the front crankshaft oil seal runs.
The sprocket is mounted on the crankshaft without interference and is not secured by a key.
During engine assembly, the driving sprocket of the pump drive is clamped between the timing drive toothed pulley and the crankshaft shoulder as a result of tightening the package of parts with the auxiliary drive pulley securing bolt.
The torque from the crankshaft is transmitted to the sprocket only through the friction forces between the end surfaces of the sprocket, the toothed pulley and the crankshaft.
If the auxiliary drive pulley securing bolt becomes loose, the driving sprocket of the oil pump drive may start to slip on the crankshaft and the oil pressure in the engine will drop.
The oil strainer is made integral with the pump body cover.
The cover is secured to the pump body by five screws.
The relief valve is located in the pump body cover and is retained against falling out by a spring retainer.
The oil from the pump passes through the oil filter and enters the main oil gallery of the cylinder block.
The oil filter is full-flow and non-demountable.
From the main gallery, the oil is supplied to the main bearings of the crankshaft, to the piston cooling nozzles and further (through the channels in the crankshaft) — to the big-end bearings of the shaft.
Through two vertical channels in the cylinder block, oil from the main gallery is supplied to the cylinder head — to the outer camshaft supports on the plug side and to the valve hydraulic tappets.
Through the grooves and drillings in the outer support journals of the camshafts, oil enters the interior of the shafts and further through the drillings in the other shaft journals — to the remaining camshaft bearings.
From the cylinder head, the oil flows down through vertical channels into the engine oil sump.
The crankcase ventilation system is closed and of the forced type.
The gases that have penetrated from the combustion chambers of the cylinders through the piston rings into the engine crankcase enter, through the channels in the block and cylinder head, the head cover.
After passing through the oil separator located in the cylinder head cover, the crankcase gases are cleaned of oil particles and then enter, through the air filter housing, throttle body, receiver and intake pipe — into the engine cylinders.
The control, fuel, cooling and exhaust systems are described in the corresponding articles.
