The K9K TURBO engine is turbocharged, in-line, liquid-cooled, with four cylinders, with an OHC valve train.
The cylinder head of the diesel engine is made of aluminium alloy.
The cylinder head gasket is made of metal, which makes it more resistant to high temperature and pressure.
The engine cylinder block is cast in grey iron with cylinder liners already formed.
The crankshaft bearings have cast-iron caps forming part of the block, including the bolts. Bearings shells are inserted in both halves of the bearings. The shells have tab locks and lubrication grooves around the central circumference.
The engine camshaft is mounted in bearing seats machined in the head body and is secured against axial movement by thrust flanges.
The crankshaft rotates in main bearings having thin-walled steel shells with an anti-friction layer. The axial movement of the crankshaft is limited by two half-rings installed in the grooves of the centre main bearing seat. The oil channels to the bearings are drilled transversely (diagonally).
The flywheel, cast in iron, is mounted on the rear end of the crankshaft and secured with six bolts. A toothed ring is pressed onto the flywheel for starting the engine with the starter motor.
The pistons are made from aluminium castings. In the piston crown on the combustion-chamber side a recess with a guide rib is machined, which ensures a swirling motion of the intake air and, consequently, very good mixture formation. A special cooling arrangement ensures cooling of the piston during the exhaust stroke. Friction in the piston assembly is reduced by a graphite coating on the piston skirt.
The piston pins are fitted with clearance in the piston bosses and pressed with interference into the upper connecting-rod eyes, whose lower eyes are connected to the crankshaft journals through thin-walled shells similar in design to the main shells. Because of the high maximum cycle pressure, the piston pin diameter is increased.
The connecting rods are steel, forged, with an I-section shank. The connecting rod and its cap are made from a single blank and machined as one piece, after which the cap is fractured from the rod by a special technology. This ensures the most accurate seating of the cap on its rod. Fitting the cap to another rod is not permitted.
The lubrication system is combined. Oil from the oil sump is drawn in by the oil pump, passes through the oil filter and is supplied under pressure to the engine. The oil pump with a relief valve is driven by a roller chain from the crankshaft sprocket. Beneath the crankshaft there is an oil deflector that prevents rapid oil surge. The aluminium-alloy engine sump is combined with the front and rear covers and, together with them, attached to the engine cylinder block.
The lubrication system also incorporates the oil heat exchanger 6 and the oil filter 3 (Fig. 5). A relief valve allowing oil to bypass is also secured in the oil filter housing. The oil filter is fitted with a replaceable paper filter element.
The engine cooling system is sealed, with an expansion tank, and consists of a cooling jacket cast in place and surrounding the cylinders in the block, the combustion chambers and the gas channels in the cylinder head. Forced circulation of the coolant is provided by a centrifugal water pump driven from the crankshaft by the accessory drive belt. To maintain the normal operating temperature of the coolant, a thermostat is installed in the cooling system, closing the large circuit when the engine is cold and the coolant temperature is low.
Turbocharging and exhaust gas recirculation system. The exhaust manifold is attached to the turbocharger flange with nuts. The turbocharger serves to increase the air pressure by means of a turbine driven by the exhaust gases. Lubrication of the turbine bearings is included in the engine's common lubrication system. The turbocharging system is complemented by an exhaust gas recirculation system. The quantity of exhaust gas admitted to the system is regulated by an exhaust gas recirculation solenoid valve, whose conical pusher changes the cross-section of the bypass port at different valve positions.
Fuel system
Into the cylinders of the diesel engine, as the piston moves down, clean air is drawn in. During the compression stroke the pressure in the cylinder rises sharply, and the temperature in it becomes higher than the ignition temperature of diesel fuel. If the piston is before TDC, diesel fuel is injected into the cylinder heated to +700—900 °C; it self-ignites, so no spark plugs are required.
However, when starting the engine after a long standstill (cold), especially if the air temperature is low, simple compression is often insufficient to ignite the combustible mixture. For this case, glow plugs are installed in the combustion chamber, positioned so that the fuel jet from the injector nozzle strikes the glowing tip of the plug and ignites.
The glow plugs are switched on automatically at the moment immediately preceding starter engagement. At the same time the indicator lamp 9 (see Fig. 7) illuminates in the instrument cluster, and the glow plugs begin to heat up to a high temperature. The main purpose of heating the plugs is reliable ignition of the fuel injected into the cylinder. After the plugs have heated to the required temperature (usually a few seconds), the indicator lamp goes out and the engine can be started. Usually the indicator lamp goes out the faster, the higher the engine temperature.
Immediately before starting the engine (or most often soon after), the glow plugs are switched off. In most modern engines they may continue to operate for up to several minutes after starting, to reduce harmful emissions during cold-engine operation and to stabilise combustion in an engine not yet fully warmed up. Then the current supply to the plugs is cut off. Thus, starting the diesel engine and its subsequent operation depend directly on the correct operation of the glow plugs.
Fuel is supplied by the high-pressure fuel pump (HPFP) directly from the fuel tank. In the HPFP the fuel is compressed before injection and then delivered to the engine cylinders in the order of their firing. At the same time the HPFP governor meters the fuel according to the accelerator pedal position. Through the injectors, diesel fuel is injected at a specific moment into the pre-chamber of the corresponding cylinder. Thanks to the shape of the pre-chamber (swirl chamber), the incoming air acquires a certain swirl during compression, so that the fuel mixes optimally with the air.
Before the fuel reaches the HPFP, it passes through the fuel filter, where it is cleaned of contaminants and water. That is why it is important to replace the filter in good time, in accordance with the maintenance schedule. The HPFP requires no maintenance. All moving parts of the pump are lubricated by diesel fuel. The HPFP is driven from the crankshaft pulley by the toothed belt.
Since in a diesel engine the combustible mixture self-ignites, no ignition system is required, and a solenoid valve is installed in the HPFP. To stop the engine, the voltage supply to the solenoid valve is interrupted, and the valve closes the fuel channel, whereby the fuel supply stops and the engine stops. When the starter is engaged, voltage is supplied to the solenoid valve and it opens the fuel channel.
Engine specifications:
- compression ratio — 18.25;
- cylinder bore — 76 mm;
- piston stroke — 80.5 mm;
- engine displacement — 1461 cm³.
Engine component tightening torques (daN·m)
- Cylinder head retaining bolts — to the sequence 2.5 daN·m, then turn a further 255° ± 10°
- Camshaft bearing cap retaining bolts — 1
- Camshaft toothed pulley retaining bolt — 3 + 84°
- Vacuum pump retaining bolts — 2.1
- Thermostat housing retaining bolts on the cylinder head — 1
- Exhaust manifold stud nuts — 2.6
- Exhaust gas recirculation valve retaining bolts — 2.1
- Glow plugs — 1.5
- HPFP retaining bolts — 2.1
- Injector flange retaining bolt — 2.8
- Fuel rail retaining bolts — 2.8
- High-pressure fuel line union — 3.8
- Cylinder head cover retaining bolts — 1
- Pipe manifold stud nuts to the exhaust manifold — 2.6
- Turbocharger oil return line union — 0.9
- Turbocharger oil supply line union — 2.3
- Timing belt tensioner roller retaining bolt — 2.5
- TDC locking pin hole plug — 2
- Cylinder head pendulum mount retaining bolts — 2.1
- Heat exchanger connecting nipple — 4.5
- Oil filter bracket retaining bolts — 4.5
- Crankshaft main bearing cap retaining bolts — 2.7 + 47° ± 5°
- Connecting rod cap bolt nuts — 2 + 45° ± 6°
- Knock sensor — 2
- Oil level sensor — 2.2
- Oil pump retaining bolts — 2.5
- Engine oil sump retaining bolts — see the procedure description
- Water pump retaining bolts — 1.1
- Flywheel retaining bolts — from 5 to 5.5
- Clutch housing retaining bolts — 0.8
- Pulley retaining bolt — 2 + 130° ± 15°
- Water pump inlet pipe retaining bolt — 2
- Multifunction bracket retaining bolts — 4
- Alternator retaining bolts — 2.1
- Power steering pump retaining bolts — 2.1
- Air conditioning compressor bolts — 2.1
