BMW N52: Everything You Need to Know

They were awarded as one of Ward’s ten best engines for two consecutive years, in 2006 and 2007. With years of expertise under their belt, BMW refined different facets of engine production, and we can say that their N52 Engine is no doubt BMW’s one of its most produced and eminent Engine.

BMW N52 is a naturally-aspirated inline-six petrol engine that debuted on the E90 3 series and E63 6 series. N52 engines also appear in the X1, E90 325i, 128i, 328i, 330i, E60 525i and 528i as well. It was produced from 2004-2015 and replaced its straight-six ally, BMW N54, following its production halt in 2006. N52s were the first water-cooled Engine that is constructed from the aluminum-magnesium composite engine block.

Though N52 is a top-notch engine, BMW N52 was, unfortunately, to be phased out in European markets since the release of the final straight-six Engine, the N53, in 2007. However, emission issues such as high sulfur levels in the fuel and were unfit for the engine job for the unaddressed issue in N53s are why most consumers in the United States, Australia, Malaysia, and Canada continue to use its previous model, the N52. Down the road, N52s were slowly being replaced by the N20 turbocharged four-cylinder until its final year production in 2015. There are two versions for N52 but no M version for this Engine.

Engine Specifications and Design:

  • Production Run: 2004-2015
  • Cylinder Head Material: Aluminum
  • Cylinder Block Material: Magnesium-Aluminum
  • Configuration: Straight-six / Inline-Six
  • Bore: 85mm
  • Stroke: 88mm
  • Valvetrain: DOHC Double Vanos, with VVL
  • Displacement: 3.0L
  • Compression Ratio: 10.7:1
  • Weight: 355 lbs.
  • Max HP: 258hp at 6,600 RPM
  • Max Torque: 222 lb-ft at 2500-4000 RPM

BMW’s initial N52 release, N52B25, is a 3-Liter lightweight powerhouse straight-six Engine. Weighing at approximately 355 lbs., it was considered one of the lightest performance engines in the six-cylinder category. The changes in materials were the primary driver in achieving significant weight reduction in this Engine, such as the usage of a magnesium-aluminum composite cast in its crankcase. The first time BMW uses magnesium alloy of a water-cooled crankcase, its engine block and cylinder head cover is also made of the same material, which is 24% lighter than aluminum ones. However, Magnesium has a higher risk of corrosion from water. It may creep under load at high temperatures, making the magnesium alloys unsuitable as a tread material or a coolant-carrying component. That is why BMW developed a magnesium encapsulation, a composite construction inserted with an AISi17 with an aluminum inner block to overcome Magnesium’s property limitations. The cylinder liners are made of Alusil (Aluminum-Silicon), and the camshafts used are hollow for weight reduction.

In comparison to M54s, its predecessor, N52 engines, are lighter due to their magnesium material. It features Valvetronic (Variable Valve Lift), an electric water pump (replacing the belt-driven water pump), and a variable output oil pump. Just like M54s, it uses electronic throttle control, variable valve timing to both camshafts (Dual-VANOS), and a plastic three-stage variable-length intake manifold (called “DISA”) where higher output versions are equipped with. But on later car models, BMW changed it to a dual intake technology keeping the same name. The redline was increased from 6,500 rpm to 7,000 pm, except for N52B25 (130kW), due to the second-generation Valvetronic that regulates the valves’ opening and control time. N52’s engine control unit is a Siemens MSV70.

N52 Engines also reach their operating temperature faster than usual due to their oil-to-water heat exchanger nature. Plus, heat management in the N52 adjusts the cooling capacity regardless of the engine speed through the thermostat map and electric coolant pump.

ULEV and SULEV Regulation Engines

Whether you are living in Europe or in America, there are regulations that need to be followed in deference to our environment, to avoid excessive amounts of carbon roaming around and it has been that way since; and that is the foundation of any engine design, may it be aerial, fluvial, or terrestrial, each has the need to control the emission that’s coming straight from the tailpipe. So, in Europe, their entire continent follows a specific scale for their emission, we heard them as the EURO 1-6, where most of the countries adopting the same concept, but in the United States, it is a little different here.

In the US, there are Ultra-Low and Super Ultra-Low Emissions Vehicles. Quite the same scale used by Europeans but classified in only two categories. Anyway, when BMW started shipping N52 engines, though some states were persistent on the imposition of higher emission standards, they’ve met the requirements needed to match ULEV, making it legal to American roads. However, due to the autonomy of some of the states, they have tapped to impose the emission regulation depending on their state policies. In some states, they decided to accept SULEV as the lowest standard, which puts the BMW in a situation where modifying the original N52 and create something that will meet the SULEV standard, which is now known as the N51 Engine.

Though there are several features and key areas where these two engines differ, vehicles with N51 and N52 engines are nearly identical, but you cannot install the parts for N51s for N52s as it can cause deep trouble for you and your vehicle.

Engine Upgrades and Modifications

N52’s high-potential is evident that if you install some performance-type exhaust system and install some sports air filter and no doubt that, not only your Engine will scream so are you with its 290hp boost at the maximum. Also, Early N52B30 versions can be upgraded to provide the Engine a 231hp push. Still, they can no longer surpass such ratings due to the three-stage DISA intake manifold necessity and proper ECU tuning.

Supercharger kits or Turbo kits are also available for both N52B25s and N52B30, which can give you 300-350hp with stock internals. You can buy a supercharger kit from the producer of your choice. However, some suggest that instead of buying supercharger kits, you may reconsider buying N54B30s and tune it via ECU through a chip that can potentially reach the Engine’s capacity up to 400hp.

Problems Surrounding N52 Engines

These are common engine problems that, hopefully not, might occur to your N52 Engine.

First is the Hydraulic Valve Adjusters. This is because the lifters do not get enough oil to function appropriately and efficiently due to their poor cylinder head and lifter design. This happens most of the time on higher mileage cars that already registered 50,000+ miles, most common during cold weather or shorter trips. You might experience periodic ticking or rattling noise coming from the Engine. Though it does not affect the Engine’s performance, it is still so terribly annoying; and that noise comes from the hydraulic valve adjusters, known as lifters. In response to the claims, BMW fixed the designs of the lifters and cylinder heads in the last quarter of 2008, especially in 2008 and prior models.

The second is the Water Pump Failure. BMW always tends to deviate themselves to the design that their competitors present, so instead of using traditional water pumps, BMW opts to use the plastic-made electric water pump, which, I’m afraid, is prone to cracking and corroding with age. Not only N52s but also N54s are predominantly affected by this issue, which mostly occurs around 80,000 miles and above. Bearings and impellers also fail within the water pump. If you notice Engine overheating, coolant leaks, and steam or smoke coming out of the radiator, it might be a water pump failure. This can be solved by replacing the water pump.

The third is the VANOS Failure. N52 engines are equipped with a VANOS system, and it is the variable valve timing system technology exclusively for BMW engines. VANOS solenoids are the ones who are responsible for controlling the flow rate that goes to the cam gears, which controls the opening and closing of the valves. However, the valves may get clogged or deteriorate over time due to their o-ring material, rubber. VANOS solenoid failure may lead to loss of power, bad fuel economy, poor idling, trouble starting, and irregular limp mode. This can be felt or may fail at around 70,000 miles. Replacing them might be the best option yet, and you can do it in 70,000 miles increments.

Recalls 

There have been reports that six cylinder models, in 328i and 525i, that the heater for the crankcase ventilation intermittently short-circuiting and causing smoke and fire. Because of that incident, BMW decided to recall 740,000 six-cylinder models in 2007.

Summary

BMW’s approach in the N52 Engine is developmental. This Engine is more economical, meticulously made, and are technologically advanced in its time. Even do they demand more care and attention, especially in maintenance and oil quality, N52s do not have major issues to be worried about that much. However, the motor of the Valvetronic may need replacement and cracked gaskets, but other than that, if you carefully prevented this by putting a specific interval to take care of the Engine, it is reliable. It can give you thousands of miles of service.

I hope that we helped clear out some clouds bugging your head regarding N52 engines, and if you must purchase, always remember the points we’ve taken here.

About Bryce Cleveland 543 Articles
Bryce founded Dust Runners Automotive Journal in 2014 as a way to write about the cars he found interesting. He currently owns a 2003 Honda CRF450R Supermoto, 2018 Yamaha MT09, 2005 Nissan Titan, and a 2012 BMW 135i. Follow him on Instagram for more @bryce.cleveland.

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