The Popular BMW B58 Inline-Six Engine Has One Big Achilles Heel

Bmw M340i Achilles Heel
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The BMW B58 inline-six is a darling of the European car tuning scene. With a closed deck block, forged connecting rods, and a forged crankshaft, it seemed like BMW finally learned from its N54 direct-injected boosted-six stumbling block and created a juggernaut. However, to long-time BMW owners, one question lingered — how would BMW, um, BMW the B58 up? Well, it turns out that some of these boosted sixes are suffering from serious oiling system issues at relatively low mileage.

Make no mistake, the B58 is an absolute beast of an engine, capable of slingshotting a 3 Series from zero-to-60 mph in under four seconds, and willing to crank out more than 400 horsepower to the tires with simple bolt-ons and a tune. It’s been available under the hood of just about every BMW on a longitudinal platform in the past few years, and this single-turbo three-liter inline-six is as smooth as you could possibly want. However, earlier examples of the B58 have one achilles heel because BMW decided to make the oil pump rotor housing out of plastic.

In theory, this was a great idea. Plastic is less thermally conductive than steel or aluminum, lightweight, and could reduce parasitic losses. Unfortunately, plastic also gets brittle with age and in cold temperatures, and as oil tends to thicken in the cold, you can probably guess what happens next.

G-series B58 owners in cold climates – check your oil pumps! We’ve had two almost new cars in our shop since february with blown engines due to the oil pump failing in freezing conditions. BMW have made an updated oil pump which replaces duoplex plastic with metal. The pictures speak for themself????
byu/mariusrisan inBMW

Yeah, that’s pretty gnarly. Oil pump failure is something you never want to encounter, and to make matters stranger, symptoms for a failed oil pump on older B58 engines run the gamut. Some report excessive oil pressure, some report insufficient oil pressure, some simply report a whining sound. The common thread? If you let any of these symptoms go for too long, you could be saying goodbye to your engine.

Screenshot 2024 06 14 At 9.48.10 am

According to the forums, being unable to check oil level through iDrive when the oil is hot is a fairly solid symptom of oil pump issues, as dramatic fluctuations in pressure will lead to the test automatically being canceled due to the self-testing function requiring tight tolerances in the oil pump.

Screenshot 2024 06 14 At 10.34.27 am

As for affected models, they’re all over the map, but failures do seem to be most common on BMW’s crossovers, specifically vehicles like mid-2020 production and earlier X5s and X7s. However, early G20 M340i owners aren’t immune either. Many 2019 and 2020 examples without the high-performance cooling and tire package (option code ZTK) came with an oil pump featuring a plastic rotor housing, and owners have reported oil pump failure, sometimes with fewer than 30,000 miles on the clock. Curiously, the ZTK oil pump, part number 11419895359, has superseded the old regular oil pump, indicating that models newer than 2020 may not have this issue.

Weirdly, all this talk about oil pump failure is somewhat reminiscent of oil pump nut failure on M54 engine of the early 2000s, except a bit worse. In those engines, the nut holding the oil pump drive sprocket would back out under prolonged enthusiastic driving, with catastrophic results. On the B58, the failure mode is a little different, but the end result could be the same.

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Alright, so let’s say that you own a B58-powered BMW that’s out of warranty and want to get this issue fixed. Figure around $1,200 in parts, but as replacement requires dropping the subframe, labor won’t be cheap. One poster on Bimmerpost was quoted $6,000 for oil pump replacement in their X5, and it’s easy to see why, given how the B58 places its timing components on the back of the engine, and the oil pump is driven by the timing system. Regardless of dealer service or saving money and going to an independent specialist, this isn’t a cheap fix, being financially up into what used to be M car repair territory. Ouch.

So, if you own a 2020 or older BMW with the B58 inline-six or are looking at one as your next daily driver, you might want to keep an eye on your oil pump. Failures seem widespread enough to render this a relatively common issue, and it wouldn’t be surprising if this becomes the modern BMW equivalent of Porsche’s infamous IMS bearing.

(Photo credits: BMW, Bimmerpost)

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64 thoughts on “The Popular BMW B58 Inline-Six Engine Has One Big Achilles Heel

  1. S52s also have that oil pump nut issue. It’s only a few hours of wrenching and less than $300 to fix proactively

    I wonder if you can fix these B58s the same way: secure the motor with a fender-to-fender brace, then drop the subframe with 30cm M12x1.5 (from memory—don’t quote me) threaded rod to get room to pull the pan like the E36/7.

    I procrastinated and it got expensive. Wire your nuts, people!

      1. Probably a smart move. But I just took mine up the road that originally convinced me to buy it yesterday: it alternately causes me to giggle with glee and squeak in alarm. The steering is almost telepathic, the brakes freakin phenomenal—and it’ll break traction with a mere twitch. I may die broke, but I’ll be giggling as I shoot backwards off that mountain 😉

  2. S52s also have that oil pump nut issue. It’s only a few hours of wrenching and less than $300 to fix proactively

    I wonder if you can fix these B58s the same way: secure the motor with a fender-to-fender brace, then drop the subframe with 30cm M12x1.5 (from memory—don’t quote me) threaded rod to get room to pull the pan like the E36/7.

    I procrastinated and it got expensive. Wire your nuts, people!

      1. Probably a smart move. But I just took mine up the road that originally convinced me to buy it yesterday: it alternately causes me to giggle with glee and squeak in alarm. The steering is almost telepathic, the brakes freakin phenomenal—and it’ll break traction with a mere twitch. I may die broke, but I’ll be giggling as I shoot backwards off that mountain 😉

  3. Nothing like a German car to remove the oil dipstick, force you to rely on the electronic dipstick sensors, then have those electronics lock you out of checking your oil during a catastrophic oil problem. I’m not specifically looking at BMW here either. High end German cars have been doing the old dipstick removal trick for years.

  4. Nothing like a German car to remove the oil dipstick, force you to rely on the electronic dipstick sensors, then have those electronics lock you out of checking your oil during a catastrophic oil problem. I’m not specifically looking at BMW here either. High end German cars have been doing the old dipstick removal trick for years.

  5. didn’t know about the other n54 issues. thought it was mostly the HPFP. oh and the brilliant sun roof drains clogging and flooding the electronics. that were placed in the lowest part of the car. I was done with bmw after that 535xi. drove great. shit engineering and construction.

  6. didn’t know about the other n54 issues. thought it was mostly the HPFP. oh and the brilliant sun roof drains clogging and flooding the electronics. that were placed in the lowest part of the car. I was done with bmw after that 535xi. drove great. shit engineering and construction.

  7. Man will walk six feet on Mars before BMW will figures out a functional oil system. Clearly, am a fan. But, somewhere in the back of a dark hall in Munich, BMW’s top engineers are figuring out how a iX can leak a pool of formerly dinosaur on your driveway.

  8. Man will walk six feet on Mars before BMW will figures out a functional oil system. Clearly, am a fan. But, somewhere in the back of a dark hall in Munich, BMW’s top engineers are figuring out how a iX can leak a pool of formerly dinosaur on your driveway.

  9. Looked around a bit more. The offending oil pump was only used in some B58s in some models. The one that Eric Gonzalez mentions below (part # 11417643046) that is found on B58s in other models does not seem to be subject to breakage. For example, it’s been used on B58s in the M240i cars and as I mentioned below, those forums do not reports issues with it. There was also mention of a software update that prevents the pump from backspinning and damaging itself(?) So I guess the moral of the story is if you own a BMW with a B58, check realoem and find out which pump you have.

  10. Looked around a bit more. The offending oil pump was only used in some B58s in some models. The one that Eric Gonzalez mentions below (part # 11417643046) that is found on B58s in other models does not seem to be subject to breakage. For example, it’s been used on B58s in the M240i cars and as I mentioned below, those forums do not reports issues with it. There was also mention of a software update that prevents the pump from backspinning and damaging itself(?) So I guess the moral of the story is if you own a BMW with a B58, check realoem and find out which pump you have.

  11. This is why I wasn’t excited about the Ineos Grenadier, having a BMW engine seems counter to the mission of the vehicle. Like any other BMW, you have to dump it before the warranty runs out.

    1. To be fair, this is an issue with older B58 engines and there are better oil pumps on newer ones, such as the detuned B58s in Grenadiers.

      I’ve been skeptical about the BMW engines in Grenadiers as well, but so far it sounds like the B58 is an exception to the usual BMW unreliability. Supposedly Toyota had a lot of influence in its design since it was to be shared between them, so… we’ll see how they do long-term. I think they deserve a chance, and could perhaps end up being the one decent used BMW engine.

      1. have a transit with a detuned eco-boost. am a fan. funny, used to want to extract more power from everything. but today’s power levels are enough

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