Common Problems With BMW's B58 Engines (According To Owners)

Those who know the BMW B58 are always eager to bring the loudest cheers whenever it's mentioned. After all, we're talking about the shining star of the BMW modular engine family and one of the brand's most dependable engines ever. It's also widely acclaimed for being fantastically smooth, efficient, and highly tunable (while ensuring reliability along with it), thanks in large part to its strong internals, forced induction system, direct injection, and advanced electronic control system. With just a bit of tuning, the B8 can make upwards of 500 hp, which, again, is great news for drivers who are always on the hunt for big power.

For those unfamiliar with the engine, here's some background. The BMW B58 is a 3.0-liter turbocharged straight-six introduced in 2015 as a replacement for the N55, and it is still being produced by BMW to this day. It features a twin-scroll turbocharger, closed-deck aluminum cylinder block, aluminum heads, forged connecting rods, forged steel crankshaft, double VANOS (BMW speak for variable valve timing), Valvetronic (variable valve lift), and a compression ratio of 11.0:1. Since launching in the 2016 F30 340i, the B58 has been used in many performance and luxury vehicles with very favorable results. These include the BMW Z4 M40i, 440i, M340i, M240i, X3, X4 M40i, X5, X7, and even the Toyota GR Supra 3.0, where it makes a whopping 382 hp and 368 lb-ft of torque. Although the B58's robust construction means there's low likelihood of faults, the engine isn't entirely perfect.

[Featured Image by M3C30 via Wikimedia Commons | Cropped and scaled | CC BY-SA 4.0]

According to posts by BMW B58 owners on the Bimmerpost forum, problems with the valve cover were most common. One driver of a loaner 2018 BMW 340i xDrive reported spending $2,544 to change their failing valve cover and oil separator, which was causing the exhaust to smoke and leak oil. Other commenters on the thread noted that this particular issue usually occurs due to the failure of the Positive Crankcase Ventilation (PCV) valve integrated with the valve cover. In a separate post, a commenter noted that the PCV valve malfunction was often accompanied by, among others, a loud squealing or whistling sound, a cloud of white or blue smoke, as well as rough or erratic idle.

As is often the case with rubber gaskets, the BMW B58's valve cover gasket is prone to leaking, resulting in oil loss and increased consumption. Experts recommend checking for signs of leakage around the gasket, soaking around the spark plugs, and having your nose on alert to pick up on burning oil smells. B58 owners also regularly experience coolant leaks, failed VANOS solenoids, and fuel injector problems. 

Fortunately, the majority of these issues can be fixed, though at a premium. According to CarEdge, BMW Z4 drivers pay around $14,592 in maintenance and repairs over the first 10 years. That being said, it's worth mentioning that a good majority of B58 owners online have only ever experienced minor inconveniences (if any at all). So, the B58 is well worth considering. We just thought it's important to highlight some of the problems you are likely to face with the BMW B58, despite its outstanding reputation.