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Today we will talk about the BMW engine, which became part of the era of atmospheric 3-liter gasoline engines. We will talk about the N52 engine. We will explain how BMW modernized and complicated its legendary inline six, and also spoil the reputation of this engine compared to the earlier M54. We will also share real experience of repairing these engines at our service stations, which is much more useful than the information that is available on the Internet.
The N52 engine was launched into production at the end of 2004 and replaced the legendary M54, which was very popular and reliable. The M54 was aluminum, with sleeves, two vanos and proved itself well. It easily lasted up to 300 thousand kilometers without serious breakdowns, and at that time became a symbol of the reliability of BMW's 3-liter inline sixes.
Before the M54, there was the M52 engine, which wasn't as successful. Before that, there was the truly iconic M50 engine, which is still used to make turbocharged versions.
This engine with a cast iron block became synonymous with reliability and durability. After the M54, the N52 appeared, which, unfortunately, slightly spoiled its reputation. ✅ We will tell you what the features of this engine are.
The N52 was produced until 2011, when it was replaced by the more economical and productive N20 engine. It was a 2-liter turbocharged four-cylinder engine, which became a logical continuation of the BMW engine line, providing excellent power and economy. The N52 was produced in several versions: 2.5 liters - 218 hp, 3 liters - 258 hp, and the top version of the 3 liter - 272 hp.
BMW had an important task: to make the engine more economical, more environmentally friendly, and at the same time not to lose performance. And this task was successfully solved with the release of the N20.
So what happened to the evolution of the N52 engine? BMW invented turbocharging, and so the N20 appeared. It removed two cylinders, reduced the volume per liter, but added a turbine, which allowed to improve all the characteristics of the engine. This explains why the era of atmospheric engines began: the turbine turned out to be more efficient, and with the addition of direct injection, excellent performance could be achieved with smaller volumes.
The N52 was installed on various BMW models, starting from the "penny" and ending with the X-series. This engine was installed on the 3, 5, 6 and 7 series models, including the E90, E92, E60 and E65, as well as on the X5 and X3. For example, on a specific instance of the E63 630i with a mileage of 100,000-230,000 km, we have real experience of operating this engine, which will be useful to both potential buyers and owners of the N52. The N52 was also installed on large 7 series models and, of course, on the X-series before restyling, such as the 2007 X5.
In Ukraine now, as you know, the situation with gasoline is not easy, and only owners of cars with LPG do not have such problems, since gas fuel is cheaper. For cars with an engine such as the N52, installing LPG is quite feasible and is common. This is due to the fact that there is a conventional injector injection, and not direct, as in later models with a turbine. On engines with a turbine and direct injection, such as the N20 or N55, installing LPG already causes problems and, in general, is impractical.
Engine iron: To reduce weight and improve efficiency, BMW decided to change the block design by placing an aluminum insert in place of the cylinders and using a magnesium frame to reduce mass.
Magnesium is much lighter than aluminum, and thus BMW tried to achieve optimal power per kilogram of mass. At the same time, engines with alusil cylinder coating instead of the traditional nicosil show great wear resistance. But it was such coatings that caused problems on the M52 engines, where nicosil could not be bored, which limited the possibilities of restoring such engines. In the M54, the situation was improved thanks to cast iron liners, but in the N52 BMW decided to try a new alusil coating, which, as the experience of the N52 showed, could lead to wear and burrs after 100-150 thousand kilometers.
The nuances with aluminum bolts and magnesium parts in the block, they create certain difficulties. But these are design features that can be taken into account during the repair or maintenance of such cars. Now, regarding the general condition of such engines - if you monitor them, they serve for a long time and reliably. In principle, if the owner does not have serious problems with the timing system or oil pump, and if you timely diagnose and replace consumables, then such engines can drive well for many more kilometers. Of course, it is important to remember that BMWs are cars with certain features, and if problems arise, they can be quite expensive to repair.
On this engine, BMW has introduced the Valvetronic system, which allows the engine to adapt to different conditions, improving efficiency and reducing fuel consumption. It replaces the traditional throttle, regulating the opening of the valves. However, this system requires regular maintenance, otherwise problems may arise.
It is important to follow the manufacturer's instructions for proper system operation. Regular inspection and timely oil changes help avoid many common problems and keep the engine in good condition.
The Volvotronic system replaces the traditional throttle, improving fuel economy and throttle response. It includes an additional eccentric shaft between the intake and exhaust shafts, as well as intermediate tappets. The eccentric shaft is adjusted by an electric motor via a worm gear.
Up to 150 thousand kilometers, there are no problems, but after that, malfunctions may occur. The electric motor and worm gear may wear out, and the connection of the eccentric shaft with the motor may collapse. It is recommended to check and replace the motor if problems arise. If there is no effect from replacing the motor, it is necessary to replace the eccentric shaft, the cost of which can be high (about a thousand dollars). Many owners are not ready to spend such money on expensive repairs.
Unlike N55 owners, where the system is still working normally, owners of other models, for example, after 150 thousand kilometers, may experience problems with the valvetronic system. If you have problems starting the engine, for example, uneven starting, the engine stalls or the wrong cylinders are working, this may be due to malfunctions in the valvetronic system. In such cases, the engine may not show errors, because the ECU does not record the problem. Wear of the electric motor brushes causes chips that change the resistance of the motor, which leads to incorrect operation of the motor.
In addition, there is a problem with the VANOS system (valve timing). Check the pressure and oil level, as pressure problems can cause malfunctions in the VANOS system. BMW replaced the oil dipstick with an electronic one, which can lead to incorrect oil level display. If the oil level is low, the engine may not run properly.
If the problem is with the VANOS, it is necessary to check and clean the valve screens located near the exhaust manifold, then check and clean the valves. In case of a problem with one of the valves, it can be swapped with another for diagnosis. If the problem persists after cleaning and checking, it is necessary to disassemble the VANOS actuators.
Problems with the engine hardware never end. Many owners don't even suspect about them until the engine needs to be disassembled. For example, there is often a problem with the wear of the exhaust camshaft journals.
This can be due to coking or low oil pressure. Camshaft wear can be accompanied by extraneous sounds, such as rustling, but many people don't even know about the problem until they see scuffs on the journals. This happened with the engine I was disassembling - there we found scuffs on the camshaft, although we first solved another problem. After that, we had to look for a new camshaft at the dismantling shops, where the sellers did not want to disassemble the engine without prepayment, because they did not know what condition it would be in. As a result, the owner had to order it abroad and wait a month. The cost of the camshaft with the bed was a thousand dollars.
There were also problems with sealing compounds, especially compared to previous models. This is due to the increased engine operating temperature. BMW increased the engine operating temperature to 112-115 degrees, which affects the durability of the seals. The pan gaskets, valve cover gaskets, oil seals and oil pan gaskets began to leak after 100 thousand kilometers. This can also lead to increased oil consumption. Some forums claim that this is due to the aluminum coating, but in fact the problem can be solved by replacing the oil caps. At elevated temperatures, they quickly harden, and their replacement is recommended from 80 to 150 thousand kilometers. At our service station, we usually change the oil caps at 150-200 thousand kilometers.
In the pre-styling, for example, the E60 is equipped with the N52 of the first modification without N. A magnesium valve cover is used there. For the owner, this practically does not matter, except that the crankcase ventilation valve is moved to the intake. The magnesium cover does not crack or deform, unlike plastic ones, where the CVCG membrane often tears, it must be changed separately. In the original, the valve cover must be changed, and problems with leaks often arise after 100 thousand kilometers. There were cases when the valve cover itself cracked, and I personally changed such a cover for a lot of money - about $ 400.
Let's not forget about the current topic for owners of N20 and diesel engines - chains . On these engines, it is recommended to change the chains after 200 thousand kilometers. There may be problems with plastic, as in the case of N20 - plastic can break and fall into the pan. We recommend checking the chains after 200 thousand kilometers.
BMW also has a version of the N52 engine under the nameplate N51. The main difference is the lack of an additional heat exchanger on the oil pan, i.e. an oil pan without a heat exchanger, which means fewer gaskets that need to be changed after 100-150 thousand kilometers.
Air supply system: In this engine, the air supply system looks somewhat simpler compared to turbocharged engines, because there is no turbine and, therefore, no problems with oils and leaks. However, on the intake side, we are waiting for interesting changes compared to previous models such as the N20 and N55. One of these changes is the system of changing the length of the intake tract. Why is this needed? The optimal speed of supplying the air mixture to the cylinder for maximum filling should be around 120 km/h or 90 km/h. However, at different speeds the air supply speed changes, so BMW decided to use a system of changing the length of the intake tract. This allows you to optimize not only the air flow rate, but also the time the fuel-air mixture passes through the intake tract, which affects the behavior of the engine and its power characteristics. The system consists of two flaps, called "DISA". For owners, this means more even torque at different speeds. As a result, the torque curve becomes smoother and the engine responds to the accelerator pedal more predictably. This also affects fuel consumption and engine responsiveness at low revs.
However, it is worth remembering that after about 100 thousand kilometers, problems may arise with these plastic flaps. They can fall out, which will lead to their entry into the collector. Such a defect cannot always be detected immediately, since no errors appear on the instrument panel. However, if the flap axis is damaged, it can fall into the cylinder and cause serious engine damage. BMW has developed three modifications of these flaps, and since 2007 the latest version has been produced, in which the blade can break off, but will not fall into the cylinder, and now it will not fall off.
According to statistics, a large throttle body is changed more often, since it operates in a wider range of revolutions. If you plan to service such an engine, it is recommended to check the condition of the throttle bodies at a mileage of 100 thousand kilometers or more.
Fuel system: It's pretty simple. Each cylinder has its own injector that sprays fuel into the intake manifold.
The mixture begins to form directly at the inlet, the air picks up the fuel, directing it to the open valve. Unlike the direct injection system, where fuel is supplied directly to the cylinders, here everything happens through the intake manifold. The fuel system is generally reliable. The tank has a submersible pump with a filter and level sensor in one half of the tank, and in the other - a flask with a filter and sensor. There are no filters in the fuel line. This engine began the line of N and B series gasoline engines, which do not have a mandatory fuel filter, which requires regular replacement. Injectors on BMWs usually do not break, and cleaning does not help if they are already damaged.
The exhaust system is simpler than in turbo engines. The exhaust manifold is implemented according to the "three-in-one" scheme. Each bank has a separate catalyst - ceramic.
There is a risk that the catalysts may eventually break down and their parts will get into the cylinders, which will lead to engine damage. It is recommended to replace the catalysts or remove them. This is usually required after a run of about 150-180 thousand kilometers, depending on the quality of the fuel and operating conditions. This system has four lambda probes: two before the catalysts and two after.
Cooling system: There are some problems here compared to the M-series, as the engine has become more loaded. The plastic on the radiators and pipes dries out faster, the rubber on the pipes also wear out faster. There is also a possibility that the antifreeze tank may crack. For example, on the E70 model this is the most common problem. The pipes, as before, can fail with age. But in general there are no such serious problems. BMW has introduced an electric pump, which improves engine warm-up and increases its efficiency.
This is the first engine with an electric pump. It used to be mechanical and everything was reliable. In winter, the pump does not turn on at all when warming up until it reaches a certain temperature. Also, when adjusting the engine temperature in different modes, the pump works with different loads. The M-series engines had a problem with the expansion tank caps - they were recommended to be changed once a year, because they could jam, lead to overheating, etc. Here, BMW changed the cap, it does not need to be changed so often, but we still recommend doing it once every two to three years, because the cap can fail. The electric pump in the antifreeze system is not a big problem, despite rumors about its premature failure. In our experience, they work without problems up to 200 thousand kilometers. There is also a thermostat in the cooling system, which has no problems with reliability. On a copy with a mileage of 230 thousand kilometers, the antifreeze pipe coming from the radiator was replaced. This is most likely related to age and mileage, as the car was in Ukraine, where operating conditions can be more difficult.
Attachments: Everything is standard, but unlike the F-series, there is a hydraulic rack and pinion steering.
In N52 models, according to experience, the power steering may require replacement at approximately 150 thousand kilometers. The generator and air conditioner are usually fine. The starter on this car was repaired by the owner, and we recommend replacing the rollers and belts every 100 thousand kilometers as standard.
Chip tuning: Naturally aspirated engines are not very suitable for chip tuning and it is not always profitable. With a chip, you can add about 15% to the moment and 5-7% to the power, but for this you need to use better fuel. For example, you can switch from 95th to 98th or 100th gasoline, which will add a little power, but the owners will not notice it, and the risk of detonation and incorrect engine operation can create additional problems.
SUMMARY:
We went through all the engine systems and, to summarize, I can say that, in my opinion, the golden age of these engines has already passed - it was in the 2010s, maybe until 2015. In those years, this engine, especially the 2.5-liter version, was criticized for its reduced reliability, especially due to problems with ring coking. Even after replacing the oil dipsticks, the oil consumption continued - for example, if the engine eats 5 liters per 10 thousand, after replacement a few liters go, but a few more liters will remain. The main problem is solved by replacing the oil dipsticks, after which the oil consumption stops.
At that time, the reputation of gasoline engines was spoiled by this engine, while diesel versions, for example, the 3.0 diesel N57, remained in demand and were famous for their reliability. Diesel engines were especially recommended for the E70, E60 and E90 models, claiming that gasoline engines, including the N52, were bad and not recommended. But personally, with experience working at a service station, my impression of the N52 has improved significantly. This is not the "bad" engine that reviewers talked about. In fact, despite its reputation, it is quite reliable, and problems such as frequent replacement of engines or their breakdowns do not occur. I would rate this engine a solid four. For example, on a car with a mileage of 230 thousand kilometers and 100 thousand on one owner, no problems arose, despite operation in Ukraine.
It often happens that cars from Europe come with service intervals of 30 or 25 thousand kilometers, which, of course, is very harmful to the engine. We recommend that you check the condition of your engine and then make a decision. Frequent oil changes can help avoid problems with engine operation, for example, with the Vanos system or oil supply. It is important that there are no burrs and coke accumulations on the camshaft.
If you take care of your engine properly, it will generally work fine. All of the problems we have listed can occur, but they may manifest themselves differently for each car. Therefore, with proper care and timely oil changes, your engine will be in good condition.
I used to think that the N52 engine was a bad engine, and after it, with the addition of a turbine and direct injection in the N20 and N55 versions, everything would only get worse. But in practice it turned out differently. The N20 and N55 engines did not inherit the problems of the N52, despite the fact that they are equally loaded and operate at high temperatures. Apparently, this is due to the fact that our customers change the oil on time and maintain engine cleanliness. Problems with the iron are rare, but sometimes difficulties can arise with the fuel system - but that's a topic for other videos. You can learn about this, for example, in our videos about the N20 and N55.
When subscribers ask about the N52 engine, I usually answer that the main problem may be in the valvetronics. But, in fact, owners of modern cars with this engine, especially in the F-series, may not worry - there will be few problems, and they will not be global. Watch more on YouTube!
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