BMW N52 Engine – 2.5/3.0 Inline-6 Engine

The BMW N52 engine is a naturally aspirated straight-6 engine that was produced from 2004-2015. While often overlooked in the argument of the best BMW engines ever made, a strong case can be made for the N52 due to its stellar reliability and versatility. Perhaps due to its underwhelming factory power figures or the fact that the N52 was never placed in any truly special cars, it rarely gets its props.

As the final naturally aspirated straight-six engine that BMW sold in the US before moving to an all-turbo lineup, the N52 represented the last hurrah for an engine formula that BMW is known for. The N52’s smooth and linear power delivery is perfectly representative of exactly how a well-sorted straight-six should behave.

The BMW N52 was available in both 2.5L and 3.0L displacements, with each displacement variant containing subvariants that ranged in power from 174-268 horsepower. 2.5L N52 variants, designated as N52B25, were primarily used in entry-level 23i and some 25i BMW models, while 3.0L N52 variants, designated as N52B30, were used in higher-trim 25i, 28i, and 30i models.

N52 Engine Overview

The BMW N52 is a naturally aspirated inline-six engine that was offered in two displacements, including a 2.5L variant and a 3.0L variant as the N52B25 and N52B30 respectively. Within both the N52B52 and N52B30 variants are further subvariants that were tuned to produce different amounts of power. Within the N52B52 family are 174bhp, 201bhp, and 215bhp sub-variants, while the N52B30 has 215 bhp, 228 bhp, 241 bhp, 255 bhp, 261 bhp, and 268 bhp variants. 

The N52 carried on the accomplished reputation of naturally aspirated straight-sixes from winning predecessors, including the BMW M54 which it replaced. BMW made some important changes and revisions to the N52 which modernized their straight-six formula. The N52 was the first water-cooled engine to feature a magnesium/aluminum engine block. The N52 also received some additional modern BMW tech including a new revised version of Valvetronic variable valve lift technology, dual-VANOS variable valve timing, and DISA variable length intake manifolds on high-output variants.

The N52 was used in a wide number of BMW vehicles between 2004 and 2015, including the E9X S-Series, E6X and F1X 5-Series, E8X 1-Series, and a number of other popular BMW models.

Internals & Major Engine Components


One of the primary aspects of what makes the BMW N52 such a great engine is its strength and lightness. BMW utilized a new and innovative block design for the N52, using a magnesium/aluminum composite material to decrease weight while still retaining strength.

Due to the fact that magnesium has a high probability of corroding over time, it is used for the crankcase shell while an aluminum inner block is used to retain structural rigidity. The N52 also uses Alusil cylinder liners, improving strength further. Overall, the N52’s block can take a healthy amount of abuse with few issues.

It is important to remember that the BMW N52 was built with weight savings at the forefront of its design. As a result, most of the engine’s internals weren’t built with massive power gains in mind.

With that being said, the N52 has shown that it can take double, and almost triple in some instances, the factory horsepower output without issue. Almost all of the N52’s internals are cast with the exception of forged connecting rods. Despite that, the N52 is almost perfectly reliable internally at stock power levels and has plenty of room to grow.

BMW N52 vs N51

The BMW N51 was born out of the need for BMW to create a more efficient engine to meet stricter super ultra-low emissions vehicle emissions regulations in a few states that passed legislation on the subject, the primary of which was California. 

The BMW N51 ran concurrently with the BMW N52, and is an almost identical engine despite a few key changes that made it better in terms of emissions regulations. On surface level, both engines are nearly indistinguishable from one another, unless you specifically look for the SULEV emissions label on the N51. The only other way to tell them apart visually is by looking for the Environmental Air Catalyst on the N51’s radiator.

Apart from the subtle visual differences, BMW made some notable mechanical changes to the N51 as well. The two most important changes come in the form of revised cylinder heads and combustion chamber allowing for a lower 10.0:1 compression ratio, and a different, integrated crankcase ventilation system. The N51 also features updated underbody catalysts. Despite the changes made to meet emissions regulations, the N51 is still rated at the same power output as the N52.

BMW N52 vs N52K

In September of 2006, the BMW N52 was modified slightly and given a new engine designation, the N52KP. While the changes were relatively minor, they are still important to note. Most of the changes to the N52 were made as a response to cold weather performance and lifter noise that was concerning to quite a few N52 owners. While BMW attempted to fix the noisy lifter tick noise with the N52K update, it only partially alleviated the issue. 

The main updates to the N52KP include a revised crankcase ventilation system integrated into the cylinder head cover, larger 6mm sten diameter exhaust valves carried over from 6/06+ N52s, and a second-generation electric coolant pump. Additionally, small changes were made to the N52K’s camshafts, crankshaft, torsional vibration dampener, and throttle valve. The N52K also received a new DME with the MSV80 designation.

General BMW N52 Information & Resources

N52 Engine Specs

Displacement2,497cc (2.5L) – 2,996cc (3.0L)
AspirationNaturally Aspirated
Fuel SystemPort Injection
Engine BlockMagnesium/Aluminum, Open Deck
Cylinder HeadAluminum
ValvetrainDOHC, Valvetronic, Dual VANOS
Bore x Stroke(2.5L) 82mm x 78mm (3.0L) 85mm x 88mm
Compression Ratio10.7:1
Horsepower174-268 HP
Torque (lb-ft)170lb-ft – 232 lb-ft
Redline7,000 RPM

The BMW N52 was used in a wide array of BMW vehicles ranging from some of BMW’s sportiest models including the Z4, to some of BMW’s family-hauling workhorses like the E70 X5. Here are the BMWs that utilized the BMW N52 engine:


The BMW N52B25 is the 2.5L variant of the N52 engine, which was used in 3-Series, 5-Series, Z4s, and X3s with the 23i designations and some 2.5i designations. As the lowest output variant of the N52, the N52B25 does not receive a DISA variable length intake manifold.

174 Horsepower Variant

  • 2006 E90 323i — Canada and Australia
  • 2004-2007 E60/E61 523i
  • 2006-2008 E85 Z4 2.5i

201 Horsepower Variant

  • 2007-2011 E90 323i — Canada and Australia
  • 2010-2011 F10 523i
  • 2009-2011 E89 Z4 sDrive23i

215 Horsepower Variant

  • 2005-2010 E83 X3 2.5si, xDrive25i
  • 2005-2010 E60/E61 525i, 525xi — except U.S. and Canada
  • 2004-2013 E90/E91/E92/E93 325i, 325xi — except U.S. and Canada
  • 2005-2008 E85 Z4 2.5si


The BMW N52B30 is the 3.0L variant of the N52 engine, which was used in a wide number of vehicle applications with 25i, 28i, 30i, and 3.0i designations. The lower tier N52B30 engines are designated as “UL” or “lower output,” and do not receive DISA. However, the more powerful N52B30 variants are designated as N52B30 “OL,” or “high output” engines and receive a three-stage DISA intake manifold.

215 Horsepower Variant

  • 2006-2007 E90/E92/E93 325i, 325xi — U.S. and Canada only
  • 2006-2007 E60/E61 525i, 525xi — U.S. and Canada only
  • 2006-2008 E85 Z4 3.0i — U.S. and Canada only
  • 2008-2011 E82/E88 125i
  • 2008-2010 E60/E61 528i, 528xi — U.S. and Canada only
  • 2009-2010 E84 X1 xDrive25i

228 Horsepower Variant

  • 2007-2013 E90/E91/E92/E93 328i, 328xi — U.S. and Canada only
  • 2008-2013 E82/E88 128i — U.S. and Canada only

241 Horsepower Variant

  • 2010-2011 F10 528i

255 Horsepower Variant

  • 2004-2007 E63/E64 630i
  • 2005-2007 E90/E92/E93 330i, 330xi
  • 2005-2008 E65/E66 730i
  • 2005-2009 E60/E61 530i, 530xi
  • 2009-2015 F01 730i
  • 2008-2011 E89 Z4 sDrive30i
  • 2009-2011 E84 X1 xDrive28i
  • 2009-2012 E87 130i
  • 2010-2011 F25 X3 28i

261 Horsepower Variant

  • 2005-2008 E85/E86 Z4 3.0si
  • 2006-2009 E87 130i

268 Horsepower Variant

  • 2006–2010 E83 X3 3.0si
  • 2006-2010 E70 X5 3.0si, xDrive30i
  • 2007-2010 E63/E64 630i
  • 2007-2013 E90/E92/E93 330i, 330xi

We have compiled some of the most commonly cited BMW N52 engine problems. While the N52 has a very solid reputation for reliability in the BMW community, there are still some problem areas with the 2.5L-3.0L inline-6. N52 lifter tick, valve cover gasket leaks, water pump failures, and oil filter housing gasket leaks are all common issues with the N52 and are good to know about if you drive an N52-powered BMW.

Take a look at the dropdown menu below to learn more about these problems or check out the more in-depth problem and maintenance guides featured below.

We have already briefly touched on the BMW N52’s infamous lifter tick problem that caused multiple redesigns over the course of the N52’s build cycle. The fact that the problem was frequent enough to warrant BMW acting on it should say something about how common it is on the N52. N52 lifter tick is most common on high-mileage N52 engines, especially during cold weather or on short trips. Luckily, N52 lifter tick is a well-documented issue that does not cause any serious engine damage but is a major annoyance to many N52 owners. 

The BMW N52’s hydraulic valve adjusters are responsible for the obnoxious ticking noise that is especially noticeable on startup. The problem is caused by a lack of air-free oil reaching the hydraulic valve adjusters upon startup. N52 lifter tick tends to be the most pronounced if you only drive your vehicle short distances at low revs, as that doesn’t allow the engine enough time to supply the cylinder head with enough oil. In most cases, the ticking noise subsides after the engine warms up and oil begins to reach the lifters. 

Ultimately, there are two potential solutions to N52 lifter tick. One cost-free method to try is “bleeding” the N52 lifters. Essentially, once the engine is warm, this consists of maintaining 2,000-3,000 revs for 2-3 minutes to try to inspire oil flow to the head. This is generally a temporary fix that won’t solve the issue completely but will help in the short term.

The only permanent solution to BMW N52 lifter tick is swapping the stock cylinder head and lifters with revised components from 2008+. This was initially covered under warranty by BMW, but no pre-2009 N52 BMWs are under warranty anymore.

Valve cover gasket leaks are a common BMW problem across the board, not just on the N52. With that being said, it is one of the most prevalent issues on the N52 and all of the N5X engines for that matter. Unfortunately, there isn’t much that you can do to prevent N52 valve cover leaks, as they are a byproduct of the materials that BMW uses in their engines and the heat put off by them.

One of the main reasons for N52 valve cover problems is the weak rubber material from which they are made. When subjected to continuous heat cycles, the rubber gaskets tend to wear rather quickly. These leaks tend to make themselves known around the 60,000-100,000 mile mark.

In addition to the valve cover gasket leaking, N52 valve covers themselves have been known to crack, also resulting in an oil leak. Early N52 engines used magnesium valve covers that were less prone to cracking than the updated plastic valve covers with integrated CCV. Unfortunately, replacing an N52 valve cover is a significantly more expensive repair than simply replacing the gasket.

N52 Valve Cover Leak Symptoms

  • Burning oil smell
  • Smoke from valve cover area/smoke from oil dripping on the exhaust manifold
  • Oil on spark plugs
  • Low engine oil light

You shouldn’t notice any N52 drive-ability issues with a leaking valve cover and/or gasket. You may notice burning oil smells in the cabin. Smoke from the valve cover area is common if the leak is bad enough. Minor leaks may not produce enough smoke to notice. The easiest way to diagnose this problem is to remove the valve cover and see if you see a build-up of oil underneath. Also, remove your spark plugs and ignition coils and see if they are coated with oil and if there is standing oil at the bottom of the valves.

This is another engine problem that affects the entire BMW NG6 engine family including the N52, N51, N54, and N55. As we have already established, the BMW N52 is mainly a leaky engine due to the gasket material that BMW uses, as well as the brutal heat cycling that the gaskets go through during daily operation. The same can be said for the N52 oil filter housing gasket. The primary job of the oil filter housing gasket is to secure the oil filter assembly to the cylinder head. The gasket ensures that no oil leaks into the connection seam. When this gasket cracks, oil is allowed to leak down the front of the engine onto other vital components like the serpentine belt.

Due to the location of the N52’s oil filter housing and the design of the engine itself, a leak from the OFHG can drip onto the drive belt and pulley, causing the belt to slip off of the pulley. Since the belt is located between the crank pulley and engine block. If this happens, there is a chance that the belt can get sucked into the engine’s front main seal. While not extremely common, this has happened to a number of N52 owners and is a well-documented problem with a number of N5X engines.

In addition to the valve cover gasket, the BMW N52 also leaks from the oil cooler gasket in the same general area. This can make diagnosing the leak location a bit trickier as they both leak into the same area. A good rule of thumb is to just replace both if one presents a problem. That will ensure that you don’t have additional problems down the line.

N52 Oil Filter Housing Leak Symptoms:

  • Conditions similar to the valve cover gasket leak
  • Oil dripping underneath the vehicle
  • Smell of burnt oil in the engine bay
  • Leaking oil on or around the intake manifold
  • Oil spots around the front side of the engine.

It shouldn’t be a surprise to anyone that VANOS solenoid failure is on the list of N52 common problems. Nearly every BMW equipped with VANOS, and especially dual-VANOS like the N52, experiences VANOS solenoid failure at some point. VANOS plays an important part in how the N52 delivers power, as the solenoids are responsible for controlling how much oil flows to the cam gears, which in turn controls the opening and closing of the valves.

You can read more about how VANOS operates in detail in our dedicated BMW VANOS System Guide. N52 VANOS solenoid issues typically begin to arise around the 70,000-mile mark, but also tend to fail slowly, so you might not notice right away.

The good news is that VANOS solenoids are very easy to access at the front of the engine and remove without the use of any special tools. Replacement N52 VANOS solenoids typically run around $140 a pair, making the job fairly painless if you opt to DIY the repair.

Symptoms of N52 VANOS Solenoid Failure

  • Power loss/limp mode
  • Engine hesitation and bogging, especially at lower RPMs
  • Rough idle
  • VANOS fault codes
  • Poor fuel efficiency

Engine Codes for N52 VANOS Failure

Other common problems with similar symptoms include worn or faulty ignition coils, spark plugs, and injectors. However, fault codes will help point you in the right direction. VANOS solenoids may be considered a normal wear and tear item. Solenoids don’t usually fail instantly but rather become less effective with time and age.

Yet another problem that is common on the entire N5X engine family, the N52’s water pump is known to fail prematurely. While water pumps are a wear-and-tear item that needs to be replaced at some point in the engine’s lifecycle, the N52’s pump tends to fail at earlier mileage than some other engines with more robust pumps. On the BMW N5X, the water pumps were switched to an electrical design rather than a mechanical pump. Both the pump itself, along with the internal impeller are made from plastic, and, like the majority of other plastic parts on the N52, crack and break over time.

BMW N52 water pumps tend to fail around the 60,000-mile mark, but there are quite a few reports of them failing significantly earlier than that. Recognizing a failing water pump early is extremely important to your engine’s health, as the water pump plays a crucial role in the engine’s cooling system. If not addressed quickly, the engine can severely overheat, leading to damage to the cylinder head and other engine components. Due to the fact that thermostat failure is also a common problem on the N52, it is recommended to change the thermostat at the same time as the water pump.

Symptoms of N52 Water Pump Failure

  • Engine overheating (even when just idling)
  • Engine malfunction iDrive warning
  • Leaking coolant
  • Steam coming from the radiator
  • Cold air coming from the air vents when heat is on
  • 2E82 and 2E81 fault codes

N52 Problems & Maintenance Guides

We have the most comprehensive resources for N52 performance upgrades. This section includes some of the most popular, cost-effective, and value-focused modifications for the BMW N52 engine. While the N52 might not be as receptive to modifications as some of the modern turbo engines, there are still plenty of worthwhile engine mods for the naturally aspirated BMW inline-6. From tuning information to performance parts suggestions, we have you covered as far as BMW N52 modifications are concerned.

Click on each modification to get a brief rundown of the mod, the benefits, and our best product recommendation. Additionally, we have a dedicated BMW N52 Bolt-On Performance Guide if you are looking for more detail on the subjects covered below.

If you have a B52B25-powered BMW and are looking for a noticeable boost in power, swapping out the factory intake manifold with a 3-stage DISA intake manifold from an “OL” M52B30 is one of the most cost-effective and simple modifications that you can do. This modification really only applies to those that have a “UL” or low-output variant of the BMW N52 that does not already have the 3-stage DISA intake manifold, as the high-output N52B30 variants found in most 30i models have the manifold from the factory.

If you are interested in learning more about how the 3-stage DISA intake manifold improves performance, we wrote an entire article on the subject which you can find linked below. But, in summary, the 3-stage intake manifold directs as much air as possible to the cylinders where the intake valves are open at a given time.

This results in impressive performance gains for the N52, especially at the top end. Overall, the stage-3 intake can provide benefits of up to 42 horsepower on an N52B25. In order to reap the full benefit of the manifold, you’ll have to install either an off-the-shelf or custom tune.

N52 3-Stage DISA Intake Manifold Upgrade Benefits

  • Dyno proven gains over 42 horsepower and 30 lb-ft when tuned
  • Noticeable gains across the rev range, especially in the middle and upper range
  • Smoother torque curve allows for more grunt above 4,000RPM

3-Stage N52 Intake Manifold Kit

N52 DISA Intake Manifold Guide

Tunes are one of the most talked-about modifications for nearly every BMW engine, due primarily to the fact that they usually provide the most significant horsepower and torque gains. While a simple flash tune can sometimes garner 75+ horsepower on modern turbocharged BMW engines, the gains are less significant on naturally aspirated engines like the N52. With that being said, a tune is still recommended to get the most out of nearly every important N52 modification and can provide some serious extra performance when paired with the other modifications on this list.

While there aren’t as many tuning options available for the N52 as there are for other BMW engines, there are still some very solid options out there. The most popular N52 tune available is the Advanced Autowerke N52 Performance Tune, which has been shown to provide gains of 15 horsepower and 12 lb-ft of torque without additional modifications. Keep in mind, those are baseline numbers and you can expect even more notable gains when paired with other bolt-on modifications.

In addition to the power and torque gains, the Advanced Autowerke tune provides other benefits including improved throttle response, a raised redline, improved fuel efficiency, and 91+93 octane support. For $500, it’s hard to argue with those benefits.

Headers are a very solid bolt-on option for the BMW N52 due to the fact that the factory exhaust manifold is the most restrictive part of the factory N52 exhaust system. The cats in the factory exhaust manifold are optimized for maximum emission reduction and hamper flow as a result.

The restrictive cats and less-than-optimized piping creates excessive backpressure that throttles performance. Reducing that back pressure with an upgraded exhaust manifold helps the engine run more efficiently. This is because a reduction in back pressure allows exhaust gases to escape faster.

As a result, the N52 community has found that there are some pretty impressive gains to be had from upgraded N52 headers. Luckily, there are a ton of fantastic N52 header options on the market. Active Autowerke headers are undoubtedly the most popular option and have a very solid reputation in the N52 community.

Like the above 3-Stage intake manifold upgrade, upgraded N52 headers have been shown to improve performance throughout the entire rev range. That is especially true if you go for a catless downpipe setup. While high-flow N52 downpipes will also provide significant gains, they won’t be quite as pronounced as catless gains. Dyno testing has shown that a bump of 20 horsepower and 15 lb-ft of torque is easily attainable from upgraded catless headers and a tune.

Best N52 Headers

BMW N52 Bolt-Ons Guide

We covered BMW N52 header upgrades in the previous section which will undoubtedly provide the best performance gains in terms of upgrading the N52’s exhuast system. However, pairing either catless or high-flow headers with an upgraded N52 exhaust will boost performance even more while also adding a nice exhaust tone.

There are a number of both fully catless and high-flow catted N52 exhausts on the market, with the former netting a bit more power while the latter will keep you emissions-compliant and won’t piss off your neighbors. If you are planning on doing more extensive modifications to your N52 in the future, a full exhaust system, including downpipes and midpipe, will become a necessity at some point.

The reduced backpressure and exhaust reversion will help improve the performance of all of the other mods done to the engine. As with most other modifications, an upgraded N52 exhaust will provide the most benefits when paired with a tune.

Best N52 Exhaust

N52 Bolt-On Mod Guide

Intakes are one of the most popular bolt-on modifications for nearly every engine and the same goes for the BMW N52. While upgrading the factory BMW N52 intake is unquestionably a good move in terms of improving performance, the gains don’t necessarily manifest in horsepower and torque gains. An upgraded N52 intake will improve power numbers marginally, usually around 1-2 horsepower, but the noticeable difference is in the improved throttle response.

The aftermarket intake argument is a heated one full of conflicting information about whether they are worth it or not. Ultimately, there isn’t a very big performance difference whether you are using a closed or open intake on the N52. While aftermarket intakes do provide a noticeable improvement to throttle response and sound, there are other options, too. The factory airbox is pretty good right out of the gate. For that reason, most N52 owners skip purchasing an aftermarket N52 intake altogether and choose to simply install an upgraded drop-in filter instead.

In addition to upgrading the factory N52 airbox itself, there is also a secondary charcoal filter in the box itself which many N52 owners recommend removing. The charcoal filter is present in most North American N52 air boxes as they absorb hydrocarbon particles from unburned gasoline to improve emissions. While the charcoal filter isn’t extremely restrictive, it does hamper airflow a bit. Most people that delete it report a marginal improvement in throttle response.

Additional N52 Performance Guides

BMW N52 Intake Manifold Upgrade Guide

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This engine page covers quite a bit of information about the BMW N52 engine and the various performance upgrades, power levels, general maintenance, problems, and reliability associated with it. If you are looking for a quick answer to a quick question about the BMW N52, take a look at the FAQs listed below.

  1. How much power can the N52 handle?

    The N52 is capable of handling upwards of 400whp on the stock block and internals. While there are instances where the N52’s stock internals have supported more than that, reliability has suffered as a result.

  2. Is the BMW N52 the same as the N54?

    No, the BMW N52 is not the same engine as the N54. Despite both being a part of the BMW N5X engine series, they are very different engines. The most significant difference between the N52 and N54 is the N54’s use of twin turbochargers while the N52 is naturally aspirated. While the N52 uses a magnesium/aluminum block, the N54 is entirely aluminum. The N54 is also a direct injection engine compared to port injection on the N52. Ultimately, the N52 and N54 share very few components, the main ones being the electric water pump and alternator.

  3. How reliable is the BMW N52?

    The BMW N52 is widely considered to be one of the most reliable BMW engines of all time. The N52 has almost no critical common problems, with most of the problems that the N52 does have being typical wear and tear issues that affect a number of other BMW engines. The N52’s most common problems include lifter tick, valve cover leaks, oil filter housing gasket leaks, VANOS solenoid problems, and water pump failure.

8020 Media N52 Videos

Other Helpful N52 Videos

Outside Resources

We have a number of guides on specific BMW N52 topics – check out all of our N52 content below or use the tabs to find our articles on specific modifications, and so on. However, there is also a ton of good content elsewhere around the N52. Check out a few of our favorites here:

All BMW N52 Engine Content

Best N52 Performance Mods

Bolt-On BMW N52 Performance Mods

Alright, this is a tough article to write after we’ve written so much of this content for turbo BMW engines. The N52’s performance potential is often overshadowed by…