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The N52 engine in the bay of a blue 2006 E90 BMW 325i Touring
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The Most Reliable E90 BMW Models Still Have Some Engine Issues

If you’re looking for a reliable used BMW, the E90 3 Series is arguably your best modern bet. Especially the non-turbocharged 325i, 328i, and 330i models, which have the N52 BMW inline-6 engine. However, no car is immune from maintenance or reliability issues, including BMWs. And the same goes for the N52-equipped E90 cars. The …
by Matthew Skwarczek
Published on
3 min read

If you’re looking for a reliable used BMW, the E90 3 Series is arguably your best modern bet. Especially the non-turbocharged 325i, 328i, and 330i models, which have the N52 BMW inline-6 engine. However, no car is immune from maintenance or reliability issues, including BMWs. And the same goes for the N52-equipped E90 cars.

The E90 BMW N52 engine isn’t perfect

The N52 engine in the bay of a blue 2006 E90 BMW 325i Touring
2006 E90 BMW 325i Touring N52 engine | BMW

‘E90’ technically only refers to the sedan version of the 5th-gen BMW 3 Series, Automobile reports. Convertibles are ‘E93s,’ wagons are ‘E91s,’ and coupes are ‘E92s.’ One MotorBiscuit writer used to own an E92 BMW. She literally describes it as “the worst car I’ve ever owned.” But, while not all of that car’s problems centered around the engine, some did. And for the sake of simplicity, I’ll be referring to all 3 Series models from this generation as ‘E90’ from here on.

The previously-mentioned E90 BMW coupe, a 328i, suffered from several oil leaks, especially from the valve cover gasket. That’s a common issue with the BMW N52 engine, BMW Tuning reports, especially in older, high-mileage examples. The oil filter gasket can also fail over time. And if oil starts leaking out, you could be out a serpentine belt and an engine.

One thing the BMW N52 engine doesn’t suffer from is carbon build-up, PistonHeads forum users report. That’s because, unlike the turbocharged N54 engine, it has port injection, not direct fuel injection. Carbon deposits are a common problem with the latter, Car and Driver reports. Also, the N52 lacks the N54’s failure-prone high-pressure fuel pump, Samarins reports.

However, like the N54, the N52 engine has BMW’s VANOS system, which is basically the German automaker’s version of VTEC, eEuroParts explains. And over time, the solenoids that operate it fail, typically after about 70,000 miles. Plus, unlike the N54, BMW gave the N52 another valvetrain-related system, called ‘Valvetronic,’ and it can also develop problems, BimmerFest forum users report.

Finally, the N52’s electric water pump and thermostat are known to fail as the years and miles pile on. It’s a common issue in many BMW engines, including the N54, AutoGuide reports. And the pump’s design makes it difficult to diagnose wear, E90Post forum users report.

But the pre-2009 E90 BMW N52 engines have some additional problems

E90 BMW N52 hydraulic valve lifter
E90 BMW N52 hydraulic valve lifter | Partsology

Another common complaint with the N52 engine is ‘ticking’ valve lifters, BimmerLife reports. The E90 BMW 3 Series has hydraulically-adjusted valves, aka ‘lifters,’ and as time goes on, they can start rattling. A handful of 2009-and-later cars have this problem, but it mainly affects 2006-2008 cars.

The issue stems from a lack of oil-flow to the lifters, BMW Tuning reports. BMW resolved the problem by fitting the N52 with a different cylinder head for the 2009 model year. And earlier E90s can receive the part. But even so, the ticking isn’t necessarily harmful, just annoying, r/BMW sub-Reddit users report.

Additionally, while it’s not technically part of the engine, the steering column lock can fail on pre-2009 cars, BimmerFest forum users report. And pre-2008 models often suffer ABS module failure.

Are these issues deal-breakers?

To be sure, repairing a BMW, E90 or otherwise, can be expensive if something major breaks, The Drive reports. But it’s worth pointing out that after the 2009 update, the E90 328i had noticeably fewer issues, CarComplaints reports. The only real annoyance is the lack of a proper oil dipstick, r/BMW sub-Reddit forum users report.

Plus, many of these issues are age-related, eEuroParts points out. Replacing a water pump, cleaning out an injector, and replacing a spark plug or ignition coil are common maintenance requirements for high-mileage vehicles. Ditto the various gaskets. The parts aren’t necessarily cheap, but then, a 3 Series is still a luxury car.

True, replacing a gasket, brittle plastic coolant hose, or broken electric water pump can be annoying. However, there are modern sturdier versions of these parts available. And it’s why we recommend getting a pre-purchase inspection by a trusted independent mechanic before buying a used car. Hopefully, you can avoid the issues our co-worker faced with that E92.

But a well-maintained E90 BMW 3 Series with an N52 isn’t necessarily a basket case.

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MotorBiscuit Staff Writer, Producer - Sedans & Coupes

Matthew Skwarczek

Matthew Skwarczek started blogging in 2015 and focuses his writing on motorcycles and engineering science. A graduate of Northwestern University, where he earned his Master’s in Chemical Engineering, Matthew served as an applications engineer for BASF before joining MotorBiscuit in 2019.

In Matthew’s words, the visceral nature of riding requires you to be in the moment. Combined with his fascination in the analytics surrounding the building and designing of cars and bikes, both modern and classic, you’ll find his voice blends functionality and phenomena. He rides motorcycles and bicycles often, photographing them as well.

Matthew has contributed to Oppositelock and is now an alumnus. He plays Dungeons & Dragons and reads sci-fi and fantasy in his spare time, and appreciates the works of Peter Egan, Sam Smith, Brandon Sanderson, and Alex Goy.