In 2011, BMW introduced the turbocharged gasoline engine N20 with a volume of 2.0 liter, which remained in production until 2017. One of its versions was a unit with a cylinder volume reduced to 1.6 liters.
On the decorative cover covering this engine is written TwinPower Turbo, but it is not about the presence of two turbines, but the division of the intake channel of the turbine from Mitsubishi into two parts. The idea to call this fact TwinTurbo belongs to BMW’s marketers to give significance to their new engine.
From the general features of the BMW N20 design it is worth pointing out the presence of an aluminum block, chain drive timing, through a toothed chain works and the drive of the oil pump. A pair of camshafts with phase shifters is provided for the cylinder head. Fuel system with direct injection and Valvetronic system responsible for controlling the air supply.
Depending on the version, the engine output varies in the range of 156-245 horsepower, and for the 1.6-liter motor the output is 170 hp. The power unit can be found on all BMW representatives from the “one” to the 5-Series and crossovers up to the BMW X4. For a limited period, the N20 was installed on the larger BMW X5, but only as part of the xDrive40e hybrid powertrain together with an electric motor. It was also used on BMW Z4 sport roadsters in the starting versions of the car.
Reliability of the unit
It is necessary to admit that the motor N20 clearly failed to Bavarian motorists, in the period of its production in terms of reliability it was the worst of all power units of the company. Its unpredictability was striking, and the number of cases of self-destruction was off the scale. The appearance of this motor under the hoods of BMW became a real nightmare for fans of the brand. In the United States in 2017, there was even a class action lawsuit in court against BMW demanding compensation of funds for problems with the timing drive.
In general, the operation of cars with N20 motors is associated with a mass of difficulties. Only if there is knowledge about weak points of the motor and appropriate operation it is possible to avoid catastrophic consequences. If you look solely at driving characteristics, you can enjoy driving with this motor.
Decorative cover
The decorative cover on the engine plays the role of an additional noise isolation screen. It provides for the presence of a vacuum receiver, if you remove the cover carelessly, there is a risk of breaking its connections. After that, the turbocharger starts to malfunction. On restyled engines, released from the second half of 2013, there is no such receiver.
Turbine
The turbine Mitsubishi TD04LR6 has undergone restyling together with the engine. If on the first versions, the vacuum actuator is responsible for the opening of the westgate, then after the update electromechanical.
TwinScroll technology provides the presence of intake manifold with two channels in order to eliminate the negative impact of exhaust gases of neighboring cylinders on each other. The introduction of such technology has helped to improve engine efficiency and increase the efficiency of turbine rotor unwinding. In terms of reliability, the turbine of the Japanese concern serves long enough and reliably. Only the practice of extraneous ringing in the turbine caused by the operation of the bypass flap thrust is widespread. The reason for its occurrence is the backlash, which appeared in the work of the snail hinge. Temporarily cope with the problem allows you to tighten the fastener, for which there is an adjusting screw directly on the rod. In this case, it is necessary to control the tightening force, so as not to limit the mobility of the flap. When repairing the rod, it is recommended to weld the old hole and drill a new one. Some masters use clips from turbines to Volkswagen AG engines, where there is a similar problem.
In cases where the ringing comes directly from the damper plate, it will be necessary to dismantle the turbine, followed by removal of the plate and replacement of the bushing. Sometimes the plate is simply welded to the arm instead of the bushings.
For electromechanical actuators of the restyling turbine, problems may occur after 200 thousand kilometers. Its replacement will cost 150-500 dollars, but quite suitable for installation and used elements after binding from the software.
Valve cover
The valve cover is made of plastic, and a mass of attachments of the Valvetronic system, TNVD and so on are installed on it. On average, the first oil leaks on the gasket begin to appear after 100 thousand kilometers. If the oil begins to leak towards the exhaust manifold, the smell of oil penetrates into the cabin. A set of gaskets costs about 70 dollars, and the vacuum pump oil seal will have to be bought separately at a price of 30 dollars.
Quite often on N20 there is a situation when the cover itself breaks, usually such cases are noted on cars with mileage from 150 thousand kilometers. Approximately the same survivability of the VKG membrane, after which the first oil leaks appear on the inlet, and in the work whistle.
The cost of the valve cover in the original costs 280 dollars, and the price tag for analogs starts at 100 dollars. On the valve VKG you can separately change the diaphragm, but the choice in favor of cheap analogs in most cases does not solve the problem, since it is much weaker than the originals in terms of elasticity.
Gasket of the heat exchanger
The problem with the appearance of oil leaks through the heat exchanger gasket and oil filter is characteristic of many BMW engines, and the N20 is no exception in this regard. Right under it is the belt of the attachment, so there is a risk of getting oil on it with the subsequent slipping of the belt and its tightening under the crankshaft pulley. In such a situation it is possible that the oil seal at the front of the crankshaft will be squeezed out.
It is recommended to change the gasket before leaks appeared on it, and it is advisable to combine the procedure with the change of the gasket located between the aluminum block and the filter.
If it is necessary to dismantle the heat exchanger, it will be necessary to drain all cooling from the system. When backfilling, the engine should not start, so the battery is required to have enough energy to keep the pump running for at least 12 minutes. The procedure is quite non-standard, so it is better to have it done by an authorized service.
Vacuum pump
The presence of a vacuum pump for the N20 motor is a must. The reason for this is the use of the Valvetronic system, which does not allow you to get sufficient discharge. In this regard, the gasoline motor from BMW is not very different from diesels.
The main problem of this pump is the passage of oil inside. It can be found even in the vacuum receiver pipes during the dismantling of the decorative cover. All to blame is the check valve of the small connector, or rather its gasket. Fortunately, such a problem is characteristic only for the vacuum system of the engine, the brake booster, also working on vacuum, is devoid of such a problem.
At first, when the problem appeared, the pump was replaced as a whole, with its price tag in the range of 350-700 dollars, but analogues are much cheaper. Later, alternative solutions were found, for example, an additional check valve was built into the main line. In China, there are substitutes for the fittings themselves with a built-in valve, and their reliability is quite good. Some craftsmen manage to change the connection without dismantling the pump.
Pompa
The pump on the Bavarian motor is electric, that is, the rotation of the impeller is provided by the work of a small electric motor. In the original its cost is about 470 dollars, but there are analogs on sale from 190 USD. In general, the pump is not bad, capable of serving up to 150 thousand kilometers, and its seals retain the tightness of the body. Problems, if any, are related to electronics. One of the consequences of such errors can be the output of the cooling fan to the maximum modes of operation.
Ignition coils
There are no special censures and to the coils. Their price tag is about 100 dollars, and the service life is about 150 thousand on the odometer. Drivers in the electronic control unit can fly off, but such a phenomenon occurs very rarely.
TNVD
For the fuel injector of the N20 engine is characterized by sufficient reliability, but the pump has its own nuances. In March 2014, its revision took place, so the units are not interchangeable in the standard version. First of all, the diameter of the connector has changed. The updated fuel injector is installed on machines of the first years of production, but in addition it is necessary to carry out a change of the wiring connector. For it will have to pay about 20 dollars and re-soldering.
Before the update, the fuel injectors worked quite reliably, but the questions were caused by the rumble, which appeared in the work at the stage of the factory warranty. One of the possible reasons for this situation is the wear of the pusher, which is responsible for the movement of the fuel pump rod. The average life of this element is about 100 thousand kilometers.
A rare phenomenon for the pump is fuel skipping. In this case, gasoline will flow down the body, getting under the valve cover, and mixing with oil. The latter will get a characteristic fuel odor. This is a sure sign of the need to replace the fuel injector. It is possible that the continuation of problems will be the failure of the oil level sensor in the system. Oil vapors penetrate into the intake through the VKG valve, and from there directly into the cylinders, as a result of which the fuel correction goes down. With computer diagnostics, the system can easily detect the error, but without it, the problem only manifests itself in the presence of more serious than usual engine vibrations.
Injectors
Bosch injectors with direct injection are also quite reliable. Often, the engine is replaced with a second fuel injector, and the injectors are still original. If there is a change, it is necessary to pay attention to the environmental class of the motor, for engines N20 Euro-V they will be different from the injectors for the motor Euro-VI. When changing the rings are changed and the sealing rings under them, after which it is necessary to write in the program correction codes.
The main signs of wear of injectors are overflow of gasoline immediately after starting the engine, which is not difficult to identify by the exhaust of blue color. It is possible that the cause of ignition skips is also a problem with the performance of the injectors. Another sign of wear is a loud clanking noise during operation.
Valvetronic system
For the BMW N20 engine, the third generation of the Valvetronic system is provided. Due to a fairly complex mechanism, it avoids the presence of noticeable steps in the process of opening the valves, which in turn allows you to do without the throttle, and the air supply is regulated directly by the valves. BMW engineers left the throttle in the manifold, but it is included in work only in emergency situations, when Valvetronic is switched off. It is necessary to recognize, by the third generation engineers were able to eliminate all childish diseases of the system, and it quite reliably functions. The collector of the electric motor is oriented downward, so dust from brushes gets on the parts less, which positively affects the wear rate.
One feature of most BMW cars with N20 motors is a very loud idle with twitching. One of the problems with this could be the Valvetronic system. After the ignition is started, the system’s servo marks the extreme position of the shaft. If the battery of the car by this time is on the “last breath”, to the actual extreme position of the shaft can not reach. For normal operation of the engine requires the maximum opening of the valves, but in the absence of data on the extreme position of the shaft and the opening will be incomplete. If the throttle is also covered with a significant layer of soot, there will be a noticeable vibration in the engine operation. This can be noticed even in the vehicle interior. Recharging/changing the battery and cleaning the throttle from soot can eliminate the problem, Valvetronic will start working again, and with it the responsiveness of the power unit to the gas pedal will increase.
One more flyhack, if the previous actions did not help – start the engine not immediately after turning on the ignition, but with a delay of 15-20 seconds.
At high mileage around 300 thousand kilometers in Valvetronic can wear out the electric motor of the actuator. Its replacement will cost 400-700 dollars, if you choose the actual part.
Over the years, gears wear out, but this is a natural process of any rubbing parts. Wear will manifest itself in the form of loss of smoothness in the operation of the power unit. When it comes to the eccentric shaft pinion, it costs about $1,400 on the market. It will occur no sooner than after 500 thousand kilometers.
Double Vanos
Each of the camshafts received Vanos phase shifters. Connection of the couplings with the shaft is provided by special bolts with holes, through which oil for lubrication enters the coupling.
The process of opening/closing the channel is regulated by a spool piston. In turn, the piston is operated by solenoids. The oil supply controls the timing, which shifts the camshafts relative to the crankshaft.
Vanos phase shifters are characterized by the occurrence of extraneous sounds immediately after start-up and the appearance of errors, after which the electronics activates the power limitation of the power unit. The cause of the problem is the wear of the clutches, their chambers lose their tightness, which does not allow to maintain the necessary oil pressure. Accordingly, it is not possible to ensure the optimal position of the camshaft angle. The cost of the original phase shifter is 600 dollars. Quality analogs with comparable characteristics are sold for 300 dollars, and the initial price tag of non-originals is three times lower.
The degree of reliability of Vanos depends on the quality of the oil. If the lubricant is regularly changed and do not skimp on its quality, phase shifters can easily survive 200 thousand, if the oil is not perfect, their survivability can be halved. Replacing the clutch requires fixing the shafts by means of a special conductor. Together with the change, it is recommended to change or clean the central valve. The cost of this element is 60-120 dollars. In rare cases, malfunctions are also possible in the work of solenoids, their price tag on the market is also about 60 dollars per piece.
GRM chain
This is the main problematic place of any BMW N20 engine. It is known quite a few cases when chains broke off at a mileage of 30 thousand kilometers. Bavarian engineers have repeatedly tried to improve the chain itself, and as a result, in early 2015, its third version was put into production.
First of all, the timing chain is very jealous of attempts to chip-tuning the engine, when the unit with a capacity of 184 hp is installed firmware for its acceleration to 245 “horses”. The consequences of prolonged standing in traffic jams or prolonged warming up are not better. For example, with regular driving on the highway, the chain can go out up to 200 thousand kilometers, especially with the regularity of oil change (the optimal change in 7 thousand kilometers). If the car is operated in the city, but also had a chip motor, the life cycle of the chain will not exceed 100 thousand kilometers. The appearance of ringing in operation is the first sign of problems. Ignoring it will cause the guides to peck out, slipping or tearing of the chain itself.
Guides made of fluoroplastic in the case of destruction form fragments that can reliably clog the oil reservoir with the subsequent turning of the liners and the death of the power unit.
In the fall of 2016, a new hydraulic tensioner was introduced, as there were quite a few complaints about chain slack in the old one.
HBT
Under the condition of standard maintenance, there will be no problems with the cylinder head. It is only necessary to regularly remove dirt from the valves on the inlet and change the oil caps every 200 thousand kilometers.
Cylinder Block
The block is completely made of aluminum, cooling jacket is of open type. Under standard operating conditions, the block is quite reliable and does not cause problems. Difficulties arise when trying to flash the engine to the maximum power of 245 “horses”.
The firmware itself is installed without problems, but the difference between the 184 hp and 245 hp motors is in the shape of the pistons and the different compression ratio in the cylinders. The more powerful engine has a lower compression ratio. To avoid problems with detonation and destruction of cylinders it is necessary to switch to 98th gasoline, but not every car owner does it, taking into account the cost of fuel. In fact, there are plenty of such cases with BMW cars.
Oil pump chain
Under the crankshaft of the engine there is a balancer shaft, to its module on the side of the oil pump is attached. Its work is ensured by helical gears. In turn, the torque is transmitted by a Morse tooth chain attached to a pulley at the front of the crankshaft.
It must be changed together with the timing chain. It is also characterized by the destruction of the guides and the chain itself breaking. The chain itself is short, and the pulley is very, very thin in diameter, but nothing else can be thought of constructively. The wear of the chain is indicated by the appearance of rustling in operation and tsokot.
Regular breakage of the oil pump chain was especially a problem in the first years of operation of the N20 engine. After identifying the causes of the malfunction, they began to change the pump drive, which led to a reduction in cases of chain breakage and fatal destruction of the power unit. The chain itself was modernized, its plates received a new design, but with doubled thickness.
When replacing the chain, a set is purchased together with guides, tensioner, gears. Its cost is 80-220 dollars, depending on the manufacturer.
Oil pump
In most cases, the operability of the oil pump is normal. It itself has no regulation, but it still gives out the right pressure. If for some reason the oil intake hole is clogged, there is a drop in oil pressure in the system, the liners turn. It is worth disassembling the element and cleaning the channel. With a worn oil pump chain, it is checked for the integrity of the internal elements.
Pistons
After the modernization of the engine in 2013, German engineers made changes in the pistons. First of all, they increased the size of the skirts on the lower edge, after which they received a pronounced trapezoidal shape. Due to this it was possible to significantly reduce the chattering of the piston at the moment when it reaches the upper point and begins to move to the lowering cycle.
The result of the update was a reduction in engine noise, as the characteristic rustling at the moment of shifting has disappeared. At the same time, the old versions of the engine under the condition of proper maintenance could go up to 400 thousand kilometers. At the same time, narrow skirts on the pistons do not have any negative effect on the wear indicators.
The pistons themselves are interchangeable, but if they are installed on the prerestyling engine, it will be necessary to additionally install updated oil injectors. They have a slightly shorter body length.
Conclusions
During 2011-2017 on BMW cars, the N20 engine was one of the most common, for many models it simply had no alternative. Over time, owners learned how to maintain this powertrain, and the 2013 update allowed to partially eliminate the initial problems. On average, every 100 thousand kilometers, it is worth arranging a major revision, change the timing chain and oil pump, replace the gaskets and seals, clean the valves on the inlet from dirt. If the car is operated mainly in highway conditions, the rate of wear of its engine will be 1.5 times less. It is worth taking as a rule to change the oil every 7 thousand kilometers. Due to this, a very large number of troubles can be avoided.