BMW’s three-liter turbocharged B58 inline-six is an awesome engine. Great response, tons of torque, absolutely huge headroom for tuning, it’s easy to see why this motor’s used in everything from the Ineos Grenadier off-roader to the Toyota GR Supra. However, one potential problem with early B58 examples can turn a simple oil change into potentially a $3,000 repair. Here’s what can go wrong.
It all comes down to the oil filter housing. Instead of a canister-style filter like most Japanese cars, BMWs use a cartridge filter that fits into an oil filter housing, which bolts onto the engine. While this arrangement does let you inspect your filter media for debris at each oil change without having to slice through a metal oil filter, it seems that BMW’s had a hard time with making this setup with lifetime durability.
The truth is, BMWs have suffered from oil filter housing leaks for years. In the N52, N54, and N55 straight-sixes found in vehicles like the E90 3 Series, a leaky oil filter housing gasket comes with the potentially catastrophic side effect of contaminating the serpentine belt, causing it to slip off its pulleys, get wrapped around the inside of the crankshaft pulley, and be ingested by the engine itself through the front crankshaft seal.
While BMW did redesign its oil filter housing for the clean-sheet B58 straight-six, it made the filter housing out of plastic. An interesting choice for a part containing hot oil and coolant, but an especially interesting choice for a part containing a cartridge filter. Generally, there are two failure methods for this part. Firstly, the plastic can simply get brittle and crack over time, causing the oil filter housing to leak oil, coolant, or even both. This has been happening to owners of early B58s for a few years now, and one can safely assume the natural lifespan of the part is as little as eight years or so. Of course, situations like that of the 2016 340i owner below where a leaky oil filter housing is one of “over 6 instances [where] coolant was leaking” are a little extreme, but the filter housing can indeed just do that.
The second failure method is related to torquing the cap for the cartridge filter. See, as soon as any oil is introduced to the sealing rings on the cap, the torque spec of 18.4. lbs-ft becomes invalid. Adding that sort of lubrication causes torque values to spike, which can overtighten the oil filter cap. Interestingly, it seems that much of this damage becomes apparent upon removal, turning a normal oil change into an expensive endeavor. As the forum post below states, “After half an hour I was advised that the oil filter housing had broken during filter removal.” Now that’s a nasty shock.
If you’re looking for a standard replacement for a first-generation B58, genuine BMW part number 11428583895 will run you $416.99 from FCP Euro without fresh gaskets and hardware. Add in the hours of labor to get this done, and you’re looking at anywhere from an $1,800 bill to a $3,500 bill for a problem that could’ve been avoided with a better design and better maintenance technique.
Oh, and this is also an issue on BMW models with the B48 four-cylinder engine—models like the 230i, 330i, 430i, 530i, and X3 30i. It’s also not BMW’s only misadventure with plastic on the B58, as certain engine variants feature plastic oil pump housings that can fail over time, eventually leading to catastrophic engine failure. While the B58 is an engine capable of cranking out some serious power, it’s not bulletproof, and it’s important to fix common issues before you go chasing serious power. So, if you own an older M240i, 340i, 440i, 540i, 640i Gran Turismo, 740i, X3 M40i, X4 M40i, or similar, keep an eye on your oil filter housing.
Top graphic images: BMW; ESC Tuning
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I can think of a few reasons BMW designs critical parts from short-lived plastic: They played with too many Legos as a kid. (Nope, I did too and I like other materials) They were so excited about the additive manufacturing process that they just 3d print every part. Or perhaps they were hungover in Materials Science class at engineering school?
I’ve owned vehicles that leaked and none of them puked their belt off and totaled the engine or destroyed themselves while I changed the oil.
Perhaps they have no incentive to change since most people lease them? Screw the 2nd and 3rd owners.