As engines age, they inherently become more attention-demanding as their parts wear. Some engines, though, are simply considered unreliable due to common failures even during their lower-mileage life. That doesn’t mean they are worth writing off, however. The BMW N54 and Audi 2.7T are both regularly called ‘unreliable’ but their performance potential outweighs any fears someone should have about them. This week, we’re looking at both the N54 and 2.7T common problems, how to address them, and why you should rethink what you’d call ‘unreliable.’

Like anything nice, the better you take care of it, the better it will take care of you. The N54 and 2.7T are no different, if you perform all the work they require to be reliable and then maintain them regularly, you’ll have exceptional engines with little risk of engine trouble down the road. 

First, let’s address the common failures N54 owners may experience, what causes them, and how you can prevent them with your N54 or prospective N54-powered project. 

Water Pump / Cooling System

One of the more common concerns N54 owners, and all modern BMW owners for that matter, should have is water pump failure. Since the water pump is electrically driven on these and other modern BMW engines, there is nothing physically driving the pump outside of an internal electric motor. If and when that motor fails, it can happen suddenly and without warning. There isn’t a belt to inspect or pulley you can physically see and hear give off the telltale signs of age, so a failing water pump can be easily missed in a visual and sensory inspection of the car. In some cases, seeping coolant or outright leaks will give away a bad water pump, but that isn’t always the case. Just because yours isn’t leaking does not mean it isn’t about to die. Regular cooling service maintenance is key to prevent water pump failure and limp mode in your N54-powered BMW. A cooling service should include fresh Genuine BMW coolant, a new water pump, thermostat, and potentially upper and lower radiator hoses depending on their condition. 

Speaking of those hoses, the heat cycling they experience deteriorates the plastic, particularly on the little nipples that sprout from the main hard connections from the rubber hoses on each end. Even the slightest hit can snap these brittle plastic components after years and miles of road use. Regularly replace these hoses with your cooling service or upgrade to silicone hoses for extended lifespans and higher strength to combat heat generated from upgraded engines. 

Assembled by ECS Ultimate Water Pump & Thermostat Kit

Turbos / Wastegates

When the N54 was fairly new, owners began experiencing turbo failure and ‘wastegate rattle’ that could ultimately lead to turbo failure as well. It took BMW quite a while to effectively understand what was happening, and by the time they did, they’d already phased out the twin turbo design with the new twin-scroll N55 variant, forever leaving the N54 behind. We now know this failure is generally associated with carbon buildup from neglecting to perform the regular walnut shell blasting needed to wash out carbon that isn’t internally cleaned off by fuel passing over the valves due to the direct-injection fuel system BMW used with the N54. There were some mechanical issues with the turbos as well, but failure was most common with engines that neglected their carbon cleaning maintenance. Now, there are two things N54 owners should do to prevent issues down the road.

First, unless your turbos are documented as new or recently replaced, it’s a good idea to at least replace your turbos with our Assembled by ECS Turbo Replacement Kit. This is everything you need to start with a fresh slate and ensure your engine produces all the power it should from it’s stock turbos. This is also a good time to consider turbo upgrades, like Pure Turbos or Vargas Turbos, to add more power and better reliability.

While you’re performing the turbo replacement, you should both tackle the walnut blasting to clean the intake valves and ports of any carbon buildup. This will prevent your your engine from breathing any of that carbon. Of course, to reduce carbon buildup permanently, we also suggest a baffled oil catch can. This simple upgrade intercepts the dirty air from the crankcase that is expelled from the PCV system before it re-enters the intake. By trapping those suspended particles, your engine won’t send any of them through the intake ports, thus preventing much of the buildup common to direct injection engines. 

Assembled by ECS N54 Twin Turbo Replacement Kit

Assembled by ECS N54 Twin Turbo VTT Stock Upgrade Kit

Oil Service / Oil Filter Housing Gasket

Another plague to N54s is their inherent need to leak oil, particularly from the oil filter housing. Naturally, we have a kit for that to replace your oil filter housing gasket and tackle your oil service all at once. This is by no means the only place you’ll experience an oil leak, but it’s one of the most annoying and commonly documented leaks. Other common leakers are the valve cover gasket, rear main seal, and oil pan gasket. Be sure to check these for any seepage and replace as-needed. With regular oil service and no leaks, your N54 will be perfectly capable of lubricating itself properly and prevent any catastrophic failure.

Assembled by ECS Oil Service Kits

Assembled by ECS Oil Filter Housing Gasket Kit

Assembled by ECS Oil Pan Gasket Kit

Injector Failure

The direct-injection system on the N54 injects fuel directly into the combustion chamber rather than into the intake manifold ports. This offers benefits for fuel delivery, but the factory injectors are somewhat failure-prone, especially as they age. It’s a matter of when they fail, not if they’ll fail. Symptoms of injector failure include hard starting, random misfires at idle, and likely will not throw a Check Engine Light. Upgrading to the newer Index 12 BMW injectors is a common fix and considered an improvement. However, unlike port injection, direct injectors do require a bit more finesse to remove and install properly. Fortunately, we have the specific tools that make injector and injector o-ring replacement easy. Our Schwaben Injector O-Ring Removal and Install tool and Injector Tool are just what you need to tackle this service. 

Assembled by ECS Fuel Injector Replacement Set

N54 Opinions

Everything on this list effectively boils down to one simple fact: these engines are now a decade or more in age and likely have seen tens, if not hundreds, of thousands of miles on the road with owners who may or may not have cared for them the way they need. Regular maintenance, preventative inspections and upgrades, and the understanding that old parts wear out will help you stay ahead of any problems that may arise with your N54. Our verdict is that the N54 is not inherently unreliable, nor is it difficult to maintain, it just requires a bit more attention when compared to non-performance engines. If you keep up with maintenance and know what your biggest problem areas are, there is no reason to think your N54 will be unreliable, even making tons of power. 

Audi 2.7T 

For the 2.7T, owners are concerned with similarly large system failures and difficult maintenance. Turbo failure, timing belt failure, leaks, and exhaust gas temperature sensor failure, among other common issues with aging engines. Again, we suggest regular service to keep your 2.7T happy. Disclaimer; it may sound like we’re somewhat proving the unreliability of the 2.7T. This isn’t the case. Yes, you may need to do a bit of work and future proofing if you buy a 2.7T-powered Audi, but that’s due to the age and condition of the car. Remember, these are nearly twenty years old and likely hundreds of thousands of miles have deteriorated several wearable parts. That’s just what happens, parts wear out. It’s a bit unfair to say ‘this engine is unreliable’ when it really just needs to be overhauled to be happy for another 200,000 miles. 

Turbo Failure

While it’s much more common with upgraded software tunes that are popular for the 2.7T, the stock turbos can fail even on completely stock engines. Whether due to age or driving style, the result is the same; a difficult turbo replacement due to their location. If you’re looking for a B5 S4 or other 2.7T for your next project, it’s in your best interest to ask about the turbos and whether they’ve been replaced in the past. If not, before you begin upgrading, you should consider either a factory pair of replacement turbos or opt for an upgraded set capable of handling more power. Unless you have proof that they’re new and show no signs of wear and tear, you should prepare to swap those turbos out immediately. This service may be a headache, but it will prevent any issues in the near to even distant future while driving your 2.7T-powered Audi.

Timing Belt

Since it’s easier to swap those turbos while the engine is out, it’s also a good idea to include a timing belt service with that job. The timing belt on the 2.7T is on the front of the engine but is virtually inaccessible without removing the front core support and bumper.* While timing belts are less complicated than their timing chain cousins, they do have a shorter operational lifespan and require more frequent maintenance. Like the turbos, unless you have proof that your timing belt has been serviced recently, you should anticipate performing this service immediately. By opting for preventative service rather than reactionary maintenance, you’ll ensure your 2.7T ownership is as enjoyable as possible with the added peace of mind that everything is working properly.

*Corrected – thank you for the MANY comments correcting the TB location.

ECS Tuning Build Your Own Timing Service Kit

Leaks (Oil / Coolant)

While no more common than any aging engine, the 2.7T is at it’s youngest over a decade old. As a performance engine, it’s likely not had an easy life, either. Gaskets and seals expand, shrink, crack, deteriorate, and eventually leak at some point. With the engine out for your timing service and turbo replacement, it’s a great time to inspect the engine from top to bottom for any hidden oil leaks. The 2.7T is packed into that engine bay so tightly that you may never see the leak or at least determine it’s source if you have a few drips on the ground. Tackling your cooling system service with the engine out and replacing any gaskets like the oil pan gasket, valve cover gaskets, rear main seal, and anything else that might leak is a great way to prevent taking the engine out in the near future to hunt down that leak. Do the job once, do it right, and you’ll never have to worry about it again.

Assembled by ECS Valve Cover Gasket Complete Kit

Assembled by ECS Rear Crank Seal Flange & Gasket Kit

Assembled by ECS Oil Service Kits

Exhaust Gas Temperature Sensors

Finally, one of the other common failures are EGT sensors for 2.7Ts. They’re a pain to get to and rather expensive, but in most owners’ experiences, they aren’t necessary. The EGT sensors monitor temperature in the exhaust to help regulate air/fuel mixtures, but they aren’t the only place your ECU takes data to determine the mixture. Many upgraded software tunes can and do code these sensors out, which will eliminate their need to be replaced.

However, if you do intend to replace them, it’s important to replace them in pairs. Only replacing one sensor can result in the system not understanding differences in signals from the new and old sensor, which will end up with the same fault codes and limp mode. 

EGT Sensor Set

2.7T Opinions

The Audi 2.7T is a well-loved engine for its power capabilities, but it’s also somewhat feared for its difficulty to service. While it may not have as many Achilles’ Heels as the N54, working on the 2.7T is somewhat more of a challenge, but that doesn’t mean you should be afraid of it. With all these services performed at once with the engine out, you’re able to undo almost two decades of abuse and ready for two more decades without problems. Since these engines are old, most of this list is to be expected. With the right approach and an understanding that all this work is necessary, the 2.7T can be seen as reliable. Just know that you’ll need to do it right the first time to have that experience.

Wrapping Up

What we’ve learned through living and loving these cars, and others that carry similar stigma, is that no matter what car it is, maintenance is key to keeping it running. The fact is, almost every engine and car model will vary wildly in their dependability when purchased second-hand. It all depends on how well they were maintained and what you do to continue that upkeep. With proper service and care, even the engines with the worst reputations can be some of the most rewarding, especially when it comes to performance. To keep up with your maintenance, that’s why we’ve created entire service kits. Whether it’s just your daily you’re keeping on the road, your race car teardown at the end of a tough season, or your project build, maintenance is critical to success and we have you covered with everything you need to wipe the negative stigma about N54s, 2.7Ts, and other ‘unreliable’ engines from the community.