Small turbodiesels have already managed to win the hearts of millions of motorists. Their main advantages are an affordable price and high efficiency, comparable to larger counterparts. One of the first automakers to start producing small diesels was Renault, which developed the very popular 1.5 dCi in collaboration with Nissan. Today, many cars are equipped with this engine.
The smallest of the Renault diesel engine line - the power unit with the designation K9K debuted on the market in 2001. The turbocharged eight-valve four-cylinder engine with a common rail fuel supply system was offered in several versions - from 64 to 110 hp. The main differences between the modifications are in the equipment with nozzles, a turbocharger, a flywheel, etc. The advantages of the unit include: relatively high power and low fuel consumption - an average of about 6 liters per 100 km. The 1.5 dCi engine is widely used in Renault, Dacia and Nissan vehicles. In the period from 2003 to 2010, the turbodiesel was installed on the Suzuki Jimny small SUV, and after the start of Renault's cooperation with Mercedes, both in the new A-class models and in the Citan van (the same Renault Kangoo only with a characteristic star on the grille).
Typical problems and malfunctions
The list of problems plaguing the 1.5 dCi is quite long. One of the most serious and most common is a power failure. As a rule, this is due to the use of low quality fuel, which is not accepted by French diesel. This is especially true for engines with Delphi injectors, which may not withstand even 10,000 km in bad diesel fuel. The cost of one nozzle is about 8-12 thousand rubles. In modifications with a simple system and "normal" nozzles, you can save a lot by trying to restore their performance. In the case of piezoelectric injectors, the only way out is to replace it.
The turbocharger on some instances can cause trouble after 60 thousand km. Turbochargers were used in two types - fixed or variable geometry.
Sometimes there are cases of turning the liners and burnout of the pistons - due to poorly working nozzles. In addition, one has to deal with the usual for diesel engines malfunctions of the EGR valve. On more powerful versions, there are troubles with a dual-mass flywheel.
Another typical problem for a modern diesel is the diesel particulate filter, which can be expensive. It’s better not to ask about the cost of a new one, but pray that the troubles associated with it bypass you. Sometimes troubles are presented by the engine control electronics: boost pressure and shaft position sensors are especially vulnerable.
As you can see from the review, there are a lot of potential problems with the 1.5 dCi engine. However, the vast majority of them are due to improper operation. To avoid unnecessary and high costs in the future, diesel car owners should make up for the gaps in their knowledge caused by the operation of only naturally aspirated gasoline engines.
Conclusion
And yet, some people consider 1.5 dCi to be a rather risky choice. At the same time, most of the owners of cars with this turbodiesel are very satisfied with their purchase and want to see 1.5 dCi under the hood in the future. Before buying such a car, it’s still worth estimating how many kilometers a year you have to wind. If the mileage is low, then a car with a gasoline engine will become more profitable. Despite some flaws, the reliability of 1.5 dCi is not inferior to most well-known diesel engines, more famous manufacturers.
Diesel engines have long gained immense popularity among most motorists. Due to the design features, they are more reliable and more economical than gasoline counterparts. To compensate for the lack of power, diesel power plants are equipped with a turbocharger.
The Renault car concern was one of the first to open the production of its own small diesel engines. The first models were developed in collaboration with Nissan engineers and were designed specifically for these two brands.
The engine first appeared on the market in 2001. The choice of the buyer was initially available in several versions with power from 64 to 110 hp. Modifications were named with three digits after the K9K series, for example: 884 for Renault Duster, 796 for Sandero, etc. Engine 1.5dci also can be installed on cars Renault Kengo, Dacia, Mercedes and Suzuki.
By design motor is a four-stroke diesel plant with four cylinders and turbocharging. The Common Rail high pressure fuel system was developed by Delphi. The pistons rotate a common crankshaft. The engine is equipped with a liquid cooling system with forced circulation.
The block with cylinders is made of a special cast iron alloy. A special manufacturing technology extends the life of aluminum alloy pistons by several tens of thousands of kilometers. Average fuel consumption is about 6 liters per 100 km in the city and on the highway. The engine complies with Euro 4 environmental standards.
Advantages
Like all diesel engines, K9K has a number of advantages over gasoline units:
- Profitability. Thanks to injection technology, higher efficiency is achieved. As a result, fuel consumption is significantly reduced;
- High power. Turbocharging increases the potential of the engine on the track with low diesel consumption;
- Environmental friendliness. The Euro 4 environmental standard, introduced in 2005, is fully compliant with Renault emissions Kango with this motor
- Reliability. The original K9K models are distinguished by a high degree of durability. Their component parts, when properly used, do not require replacement for a very long mileage.
All the positive characteristics of the engine appear only with careful operation. Diesel installations require different behavior on the road than gasoline ones. Following all the manufacturer's recommendations will significantly increase the durability of the motor.
Common Problems
Not all buyers are lucky with 1.5 dci. Many complain about sudden breakdowns and very expensive repairs. The most common problem is the cranking of the connecting rod bearings and the burning of the pistons.. As a rule, it manifests itself with a run of over 150 thousand km. Replacing and repairing a damaged part can cost more than the engine itself. The main cause of the problem is faulty injectors.
Injector failure, in turn, is a consequence of the use of low-quality diesel fuel. It is not uncommon for Delphi components to fail after 10 thousand kilometers. And this despite the fact that the price of one nozzle reaches 12 thousand rubles, not counting the fee for its replacement. The nozzles of this company are piezoelectric, that is, they cannot be repaired. After 60 thousand km, problems with the turbocharger may appear. The cost of repairing this part depends on its type. The 1.5 dci used two types of turbochargers: fixed and variable geometry.
Traditionally for diesel engines, the recirculation valve, dual-mass flywheel and particulate filter can break. The latter is especially unpleasant financially. Buying and installing a new one will cost at least 20 - 25 thousand rubles. Along with this, electronics often fail - boost and shaft position sensors.
Based on all the shortcomings, many car owners consider this engine a very risky choice to buy. High mileage may signal the desire of the seller to "get rid" of the problematic part. Others, on the contrary, are satisfied with the reliability and efficiency of the motor. In any case, the characteristics and term of full-fledged work entirely depend on the care of the car owner. Better performance can be achieved by using quality lubricants and fuels.
Service
It is recommended to fill in only oil certified by Renault. The list of oils is regulated by the RN 0720 approval. It determines the safest types of lubricants for diesel engines. These include ELF solaris DPF 5W-30 and MOTUL Specific 0720 5W-30. If the engine does not have a particulate filter, 5W-40 would be the best choice. It is necessary to fill in new oil at intervals for every 20 - 25 thousand kilometers or 1 year of active use of the car.
It is very important to check the correct amount of lubricant in the engine. When replacing, it should be no more than 4.3 liters (if the oil filter does not change) and up to 4.5 liters (when replacing the filter). It is advisable to change the timing belt every 60 thousand km. The air filter in the conditions of country roads is recommended to be changed every time there are obvious signs of clogging.
When using any diesel engine, follow a few rules:
- Maintain oil level. Its decrease will cause oil starvation, one of the most dangerous processes for a diesel engine. Lack of lubrication leads to rapid wear of bearings and failure of the engine itself;
- Check fuel quality. A low-grade diesel quickly disables the nozzles, which will surely cost a pretty penny during repairs;
- Maintain medium speed. Driving at high RPM for extended periods of time can cause the turbo to "twist". Low speeds also have a bad effect on the turbine, so it's best to stick to average values;
- Perform timely maintenance. Just-in-time replacement of spare parts and oil significantly extends the life of any engine.
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The K9K TURBO engine is a supercharged, in-line, liquid-cooled, four-cylinder, with ONS gas distribution mechanism.
The diesel engine cylinder head is made of aluminum alloy.
The cylinder head gasket is made of metal, making it more resistant to high temperature and pressure.
The engine cylinder block is cast in gray cast iron with cylinder liners already formed. The crankshaft bearings have cast iron caps that are part of the block, including bolts. Inserts are enclosed in both parts of the bearings. The bearings have tongue locks and lubrication grooves along the central circumference.
The engine camshaft is installed in a bed of bearings made in the body of the head, and is fixed from axial movement by thrust flanges.
The crankshaft rotates in main bearings with thin-walled steel liners with an anti-friction layer. The axial movement of the crankshaft is limited by two half rings installed in the grooves of the bed of the middle main bearing. Oil channels to the bearings are carried out transversely (diagonally).
The cast iron flywheel is mounted on the rear end of the crankshaft and secured with six bolts. A gear rim is pressed onto the flywheel for starting the engine with a starter.
Pistons are made of aluminum castings. In the bottom of the piston on the side of the combustion chamber, a recess with a guide rib is made, which ensures the vortex movement of the intake air and, as a result, a very good mixture formation. A special cooling circuit keeps the piston cool during the exhaust stroke. Friction in the piston group is reduced due to the graphite coating of the piston skirt.
The piston pins are installed in the piston bosses with a gap and are pressed with an interference fit into the upper heads of the connecting rods, which are connected with their lower heads to the connecting rod journals of the crankshaft through thin-walled liners, similar in design to the main ones. Due to the high maximum cycle pressure, the piston pin diameter is increased.
Connecting rods are steel, forged, with an I-section rod. The connecting rod and its cover are made from a single blank and processed in one piece, after which the cover is chipped from the connecting rod using a special technology. As a result, the most accurate fit of the cover to its connecting rod is ensured. In this case, the installation of a cover on another connecting rod is unacceptable.
Combined lubrication system. oil flow. The oil from the oil sump is sucked in by the oil pump, passes through the oil filter and is pressurized into the engine. The oil pump with overpressure valve is driven by a roller chain from the crankshaft sprocket. Under the crankshaft of the engine is an oil deflector that prevents the rapid overflow of oil. The aluminum alloy crankcase is integrated with the front and rear covers and together with them is attached to the engine block.
An oil heat exchanger 6 and an oil filter 3 are also embedded in the lubrication system (Fig. 5). An overpressure valve is also fixed in the oil filter housing, which provides the possibility of reverse oil bypass. The oil filter is equipped with a replaceable paper filter element.
The engine cooling system is sealed, with an expansion tank, consists of a cooling jacket made in casting and surrounding the cylinders in the block, combustion chambers and gas channels in the cylinder head. Forced circulation of the coolant is provided by a centrifugal water pump driven by a crankshaft by an auxiliary drive belt. to maintain the normal operating temperature of the coolant in the cooling system, a thermostat is installed that covers a large circle of the system 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, which is driven by the exhaust gases. Turbine bearing lubrication is included in the overall engine lubrication system.
The turbocharging system is supplemented by an exhaust gas recirculation system. The amount of exhaust gases supplied to the system is regulated by an exhaust gas recirculation solenoid valve, the cone-shaped pusher of which changes the cross section of the bypass hole at different valve positions.
Supply system. When the piston moves down, clean air is sucked into the cylinders of a diesel engine. During the compression stroke, the pressure in the cylinder rises sharply, with the temperature in it becoming higher than the ignition temperature of diesel fuel. If the piston is before TDC, then diesel fuel is injected into the cylinder heated to a temperature of + 700-900˚C, which ignites spontaneously, so spark plugs are not required.
However, when starting the engine after a long idle (cold), especially if the air temperature is low, simple compression is often not enough to ignite the combustible mixture. For this case, glow plugs are installed in the combustion chamber, which are located so that the jet of fuel from the nozzle atomizer hits the hot tip of the candle and ignites.
Glow plugs automatically turn on at the moment immediately preceding the starter is turned on. At the same time, signaling device 9 turns on in the instrument cluster (see Fig. 7), and the glow plugs begin to heat up to a high temperature. The main purpose of heating candles is the confident ignition of the fuel injected into the cylinder. After heating the candle to the required temperature (usually it takes a few seconds), the indicator goes out and the engine can be started. Typically, the warning lamp goes out faster, the higher the engine temperature. Immediately before starting the engine (or most often shortly after), the glow plugs are switched off. In most modern engines, they can continue to run for up to several minutes after starting to reduce harmful emissions into the atmosphere when the engine is running cold, as well as to stabilize the combustion process in an engine that is not yet fully warmed up. Then the current supply to the candles stops.
Thus, the start-up of a diesel engine and its further operation directly depend on the correct operation of the glow plugs.
