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BMW has some legendary engines in its portfolio, and has produced some iconic motors over the years. In 2007, it launched the popular N54 engine, which quickly gained a reputation for being one of the most powerful BMW engines ever made.
The 3.0L twin-turbocharged inline-6 engine produced 300+ hp and 310 lb-ft of torque, thanks to its open-deck aluminum block, forged crank, and a host of other performance-enhancing features.
Despite this, the N54 engine has had its fair share of problems. In fact, it’s become one of the most controversial BMW engines ever produced.
So, is the BMW N54 engine reliable?
The BMW N54 has earned its reputation for being unreliable thanks to several common problems that are very expensive to fix. It’s also highly tunable, meaning many of the engines get modified and therefore have a greater chance of early failure.
But how long can an N54 engine last? And how does it compare to its successor, the N55? We’ll answer all of these questions in this article, while keeping technical jargon to a minimum.
Which BMWs have N54 engines?
A number of BMWs were fitted with the N54 engine from 2007 onwards. These included:
|135i / 1M
|E82 / E88
|335i / 335is
|E90 / E91 / E92 / E93
|E60 / E61
|sDrive 35i / sDrive 35is
|B3 S / B3 GT3
Is the N54 engine considered unreliable?
Unfortunately the BMW N54 engine is not particularly reliable thanks to a number of inherent design faults with auxiliary engine components. Many N54s are also modified, driven hard, and not maintained correctly which can compound the engine’s issues.
The N54 has a reputation for being fast but fragile. Some problems can appear as early as 60,000 miles, particularly when the engine hasn’t been properly maintained throughout its life.
Many of these problems are costly to fix and require expensive OEM parts, and expert BMW technicians to carry out the work.
And once you hit 100,000 miles, the problems can start adding up even faster. Let’s have a look at some of the most common N54 problems based on owner complaints.
Most common BMW N54 problems
1. High Pressure Fuel Pump (HPFP) malfunction
The most complained about issue with the N54 engine is HPFP failure, the pump responsible for supplying fuel from the gas tank to the engine. Quite important, then…
It could occur as early as 60,000 miles, and the problem was so prevalent that BMW ended up recalling over half a million vehicles to replace the HPFP or upgrade the car’s software.
If your BMW wasn’t one of those recalled and you’re out of warranty, you may be out of luck as well. This is an extremely expensive part to replace.
- Engine warning light
- Limp mode
- Engine spluttering
2. Serpentine belt failure
The serpentine belt is responsible for driving a number of the car’s auxiliary components, such as the water pump, alternator, and power steering.
If it starts shredding, you’re in for a world of hurt. And unfortunately, cars fitted with the N54 engine are especially prone to serpentine belt failure.
Not only would you need to spend money on a new belt, but it may also wrap itself around other components in its bid to escape, causing even more damage.
If you hear a squeaking noise from the engine bay, it’s time to get your serpentine belt checked.
3. Major oil leaks
The N54 isn’t the only car in history to experience oil leaks, but it’s a problem that seems to crop up more often than it should.
Problematic areas include valve cover gasket, oil filter housing, and oil pan gasket. The latter being particularly expensive to repair.
This is a very common problem and can show up as early as 75,000 miles, and many owners report leaks from multiple areas of the engine.
Seemingly as soon as one leak is fixed, the next springs up.
4. Clogged fuel injectors
A build-up of carbon can often lead to fuel injectors becoming clogged and starting to leak. It’s another common problem that N54 owners complain about.
Unforunately, when the fuel injectors leak in this particular engine, they have a tendancy to soak the spark plugs below, creating even more problems.
The main sympoms of clogged fuel injectors include:
- Engine misfire
- Rough idle
- Difficulties starting the engine
5. Water pump failure
The cooling system is also known to be problematic in the N54 engine, and the water pump is one of the main culprits.
It’s an expensive part to replace, and the repair isn’t particularly straightforward either.
The water pump is an essential piece of kit for keeping the engine cool, and failure can spell disaster if the engine overheats as a result.
Unfortunately the water pump can fail with no warning, and it’s for this reason that some N54 owners choose to replace this part preventively once they reach 70,000 miles.
6. Turbocharger failure
Ah yes, we’ve saved the scariest one for last. The turbocharger wastegate protects the engine, and the turbochargers themselves, from excessive pressure.
If the wastegate fails, the turbochargers will spin too fast and ultimately blow, leading to a hefty bill for two new turbochargers.
It’s a serious problem that can cause extensive damage, and can happen before 100,000 miles.
Symptoms of a failing wastegate include:
- Rattling from the engine bay
- Reduced power
- Exhaust smoke
Can an N54 be Reliable?
Despite its reputation for being unreliable, there are actually many happy N54 owners out there who have kept their car running strong for well over 200,000 miles. This does come at the cost of preventive maintenance and being proactive about fixing issues as soon as they crop up.
For the best chance of reliability:
- Stick to BMW’s maintenance schedules
- Pay close attention to the car and don’t ignore any warning signs
- Be proactive about fixing issues as soon as you notice them
- Be aware that modifications can make the N54 less reliable
- Get to know a good BMW mechanic who has experience working on the N54
As with any engine, the key to reliability is preventative maintenance. This is even more true with the N54.
One of the reasons the N54 is so popular is because of its tunability, but unfortunately any modification comes with its risks. It’s often modified N54s that have the most problems.
We’re not saying don’t modify your N54; just be aware that it might make it more difficult (and expensive) to keep on the road in the long run.
Despite this, if you can stay aware of the main engine issues we detailed earlier and fix them as soon as they present themselves, you can actually enjoy many miles of motoring with an N54.
N54 vs N55 reliability
The N55 is more reliable than the N54 as many of the issues that plagued the N54 were resolved. However, the N55 does still suffer from some of the same costly issues as its predecessor.
The N55 first went into production in 2009 as a replacement for the N54, and performance-wise was very similar.
It was fitted with a single turbo instead of twin-turbo setup, a Valvetronic system with variable lift control (a VANOS enhancement).
The major components were also cast manufactured, instead of using the forged manufacturing technique. This resulted in a much better, efficient, and reliable engine.
BMW learnt some important lessons from the N54, and many of the reliability issues that caused such headaches for owners were addressed.
However, there were still some significant problems that N55 owners faced, including the infamous high pressure fuel pump failure that the N54 suffered from. This issue usually presented itself in early N55 engines.
The N55 does remain a much more reliable engine than the N54, however, it’s not quite as tuner-friendly. This is part of the reason many enthusiasts still prefer the N54.
To summarise our findings on the reliability of the BMW N54 engine:
- It’s considered unreliable thanks to some design faults with some auxiliary engine components and the high probability of modification by the current or previous owner.
- The main issues include high pressure fuel pump malfunction, serpentine belt failure, major oil leaks, clogged fuel injectors, water pump failure, and turbocharger failure.
- Each of these common issues can become very expensive to fix.
- Reliability can be improved by sticking to maintenance schedules, quickly identifying and dealing with problems when they arise, and not modifying the engine.
- An N54 can still last well over 200,000 miles when cared for correctly
- The N55 engine that replaced the N54 is more reliable, but is less tunable.
Despite its issues, the N54 remains an extremely popular engine with BMW fans from all walks of life, particularly those who like to tune and modify their cars.
It was a venture back into the world of turbocharged engines for BMW, and while it’s not been the most reliable engine ever made, it will always be remembered fondly.
Do you own an N54? Are you happy with its performance and reliability? Let us know in the comments below.