These BMW N52 Years Have The Most Problems
Oh, BMW, how wonderful it was when you preferred making horsepower via stratospheric redlines rather than turbos. You experimented with V10 M5s and V8 M3s that sound oh, so intoxicating when the accelerator hits the floor. Even your bog-standard volume-selling inline-6 models got cool, unique tech. Look at the N52, one of the last BMW sixes that breathed exclusively through the atmosphere rather than forced induction. It was made from 2004 through 2015, had a super-light magnesium/aluminum alloy block, displaced either 2.5 or 3 liters, revved to 7,000 rpm, made up to 268 hp, and is extremely reliable.*
Dangit, there's that stupid asterisk. Fine, the N52 is reliable "for a BMW," as pointed out by readers when we asked what the best used car values are right now. Let's talk about the N52 years that will give you more trouble than others.
Pre-2009 N52s have hydraulic valve lifters that don't get enough lubrication, causing them to tick or rattle. Post-June 2006 N52s can have misfires due to faulty ignition coils. N52s made since March, 2005 can suffer from insufficient oil pressure in the variable valve timing (VANOS) control pistons. Post-September 2006 N52s have crack-prone valve covers made of plastic instead of magnesium, like the earlier engines, and a revised water pump that's more prone to failure. Examples built between September 2009 and November 2011 may experience issues with the VANOS phasers, thanks to weak bolts that can break.
The variance of the variants
Looking at the Venn diagram of issues listed shows the most "problematic" N52 years would be 2006 to 2011, but really, none of these issues should scare you away from seeking an N52-powered Bimmer. By this point, previous owners have probably addressed many or all of these problems. Dealing with an N52 is Toyota Camry-like compared to, say, the Sisyphean struggle you'll face with an E65 BMW Alpina B7.
There are several variants of the N52, including the original version produced from 2004 to September 2006, and the post-September 2006 N52K, which introduced some fixes and some new problems. Crankcase ventilation was no longer external, but was instead built into the cylinder head cover. The N52K carried over the 6mm exhaust valves that were enlarged from 5mm in the N52 in June 2006, and also got stiffer connecting rods. N52Ks also received new engine management software, going from MSV70 to MSV80. The airflow meter, which BMW calls a "hot film meter," went from analog to digital.
Unfortunately, it's these N52Ks that have the plastic valve covers and more failure-prone water pumps. You can have your N52K upgraded to a magnesium valve cover, though people who've done it say it's a massive pain. At least BMW did address the valve-lifter issue starting in October 2008 with improved hydraulic valve lifters and roller drag levers. By the end of November 2008, all N52s had the upgraded parts.
Rarer versions and universal problems
You may have also seen two other variants: the N52N and the N52T. As far as every BMW forum says, the N52N is basically the N52K with an arbitrarily different designation. The N52T, despite what the name might imply, does not have a turbo slapped on. The N52T was used in the 528i and X3 28i from 2010 to 2012 and featured the most torque of any N52 variant at a whopping 230 pound-feet. Yeah, okay, the 564 lb-ft in a 2026 BMW iX xDrive60 will make your life a bit better if all you want is pure thrust, but hearing a high-winding BMW N52 inline-6 will feed your soul with the music it craves.
Now, some problems are common to all N52s. For example, oil filter housing gaskets deteriorate, allowing oil to leak. Engine heat also slowly breaks down gaskets for the valve cover and oil pan.
Then there's the so-called "Mickey Mouse" flange, which is in a ton of BMW engines made from 2006 through 2018, N52 included. This flange connects the thermostat and the cylinder head, and when it fails, a nasty coolant leak is the result. It's just one part in a long line of BMW's various plastic pieces that suffer from embrittling, and now that models with the N52 engines range from 21 years old to 10 years old, this flange is a ticking time bomb for engines that use it. Fortunately, aluminum replacements are easy to come by.
The N52's noise — and manual transmission — help make it great
If you love your B58 twin-turbo inline-6, that's great. It's a beast in the BMW M340i, a hybrid sport sedan that feels like an M3, where you get low 12-second quarter-mile times, seating for five, and darn good reliability to boot.
But the N52 represents the apex of that old naturally aspirated screaming ethos BMW used to espouse. Plus, you can't get a manual in the M340i; that transmission's reserved for two-seat B58-powered Z4s and Toyota Supras. If you want a BMW where you can row your own gears and enjoy the response of a turbo-free sonorous inline-6 with four of your friends, then you'll have to head to the classifieds and find a used E90 330i or E60 530i.
Should you be lucky enough to enjoy a stick-shift N52 Bimmer, just keep after the maintenance of your engine, look out for plastic parts that crumble with age, and this fabulous engine will serve you well. Plenty of owners get 200,000 miles out of theirs! Honestly, it's impressive how durable and reliable the N52 is, given how much tech BMW threw at it. From the magnesium alloy block to the variable valve timing system to the electric water pump, it was a marvel for the time. Really, it still is.
