Common BMW B58 40i Engine Problems
BMW’s B58 began production in 2015 and was initially released in 2016 40i models. Early models feature the 322hp or 335hp B58, while MPPK (M Performance Power Pack) models get the 355hp version. Certain G series models began receiving the updated B58TU1 in 2019. The TU1 update is mostly intended to improve emissions. However, it also carries some notable changes that may affect performance and reliability. Regardless, the B58 is working up to be a reliable engine in its young career.
BMW B58 vs B58TU1
Let’s examine the changes from the B58 to the B58TU1 before we dive into any common problems. First, the B58TU1 is available in “ML” (middle output) or “OL” (high output). The ML variant makes 335hp while the OL features a staggering 382hp. B58TU1 technical changes include:
- Revised fuel system
- Particulate filters
- Timing chain re-design
- Crankcase re-design (crankshaft and walls)
- Updated cylinder head with integrated manifold
This is quite the list of changes. We’ll do an in-depth post on this in the future. For now, it’s important to note that some of these changes may affect reliability. However, it’s too early to tell. BMW’s B58TU1 is barely over a year old. Time will tell what effects the updates have. We will update this post accordingly in the future.
The 4 Most Common B58 Engine Problems
Again, we’ll probably do some editing in the future. This post is a bit premature given the B58’s age. However, there are still a few things we already know. For one, the B58 appears more reliable than the N54 and N55 were in their first four years. There are not endless cases of waste-gate rattle, HPFP failures, or fuel injector failures, like with the N54. Good start. Two, most things we know aren’t really “common” problems, yet. Yet another good start. Nonetheless, we believe these following problems will soon be regarded as common (or already are):
- Coolant Consumption/Loss
- Valve Cover Gasket
- Oil Filter “Disintegrating”
- VANOS Solenoids
We’ll break down these B58 common problems in-depth and discuss why they made the list. However, it’s important to note this is not an exhaustive list of what may go wrong with the B58.
B58 Coolant Loss
Writing about this being an issue may simply be blowing smoke. Though, it’s worth mentioning and paying attention to as the B58 ages. Many B58 owners are experiencing low coolant in the main tank. Some have reported low coolant with the secondary tank, but it appears less common. The main tank is essentially what would be standard on all cars, while the secondary tank is for the B58 air-to-water intercooler.
The odd thing is – the coolant loss hasn’t really been pinpointed to any specific cause or underlying issue. Sure, some have experienced miscellaneous leaks from gaskets, water pump failures, turbo issues, etc. However, a lot of B58 owners experience coolant loss with no visible leaks or other issues. Here are a few symptoms and things to look out for if you’re losing coolant:
- “Natural” coolant loss
- Visible leaks
- Coolant tank cap
- Coolant mixed with oil
- Pressure test system
B58 “Natural” Coolant Loss
OK, there are a few things to this. “Natural” is in quotations for a reason. There really should be no such thing as natural coolant loss. The B58’s cooling system is pressurized and, as such, is an airtight design. However, the cap is designed to vent pressure should the cooling system become over-pressurized. It’s very possible the B58 coolant tank caps are not airtight enough.
However, it’s fair to chalk up minor coolant loss to being natural. Don’t panic and waste money tracking down an issue that may not exist. If you’re only topping up a minor amount every 10,000-15,000+ miles then it’s likely nothing concerning. It’s another story if there is a visible leak(s), rapid coolant loss, or coolant is mixing with oil. Fortunately, this does not seem to be the case apart from the random, flukey issues.
B58 Coolant Loss Fix
Time will tell if there are underlying issues with the B58 cooling system that are causing coolant loss. For now, it appears most cases of coolant loss can be attributed to “natural” loss. If you’re losing coolant slowly then it probably does not warrant much concern. You could try replacing the cap to see if that has a positive effect. Otherwise, if you’re losing coolant and topping up frequently then it’s worth looking further into. Check for any visible leaks and/or pressure test the system.
B58 Valve Cover Gasket (VCG)
Well, like all of the modern, turbo BMW engines, the valve cover gasket is made of rubber. As such, we suspect the B58 valve cover and gasket to follow in the footsteps of the N54 and N55. Be prepared for potential B58 oil leaks from the valve cover gasket. These leaks commonly develop around 70,000 to 100,000 miles. Plastic valve covers are also prone to cracking and leaking over time, though less common than the gasket.
Now, we left out some potentially promising information. Although the B58 uses similar rubber VCG’s, the engine has one advantage. One major killer of gaskets are the constant heating and cooling cycles they’re subjected to. This is where the B58’s heat encapsulation system may come into play. It can trap heat for up to roughly 36 hours. As such, the B58 gaskets should be subjected to less drastic temperature changes. This may help with longevity. We doubt this will totally eliminate valve cover gasket oil leaks, but it may buy some extra time.
B58 Valve Cover Gasket Leak Symptoms:
- Burning oil smell
- Smoke from valve cover area
- Oil on spark plugs
- Low engine oil light
You shouldn’t notice any B58 drive-ability issues with a leaking valve cover and/or gasket. You may notice burning oil smells in the cabin. Smoke from the valve cover area is common if the leak is bad enough. Minor leaks may not produce enough smoke to notice. Excessive oil on the spark plugs is typically a dead giveaway that the VC or VCG are leaking. Hopefully it’s not as bad as the below image.
*Picture is from an N54 that had a leaking VCG for nearly 20,000 miles
Replacing B58 Valve Cover and Gasket
The B58 valve cover gasket is only ~$30, so this likely isn’t too concerning an issue for the DIY crowd. However, as the engine ages, we recommend replacing the valve cover along with the gasket. The VC is prone to cracking and leaking, too. It’s a pretty labor intensive job. As such, it can’t hurt to replace the valve cover while you’re in there. Though, it may be excessive on lower mileage B58’s. Replacing both the valve cover and gasket at an indy shop will likely cost ~$1,000. Of course, this may vary a lot from shop to shop.
*Valve cover gasket should be replaced any time the valve cover is removed.
B58 Oil Filter “Disintegrating”
We were surprised to find this is not uncommon on other BMW engines, too. The B58 oil filter is prone to shearing at the bottom. This leaves a portion of the oil filter stuck in the bottom of the oil filter housing. Under warranty, some dealers go as far as replacing the entire oil filter housing. However, this may not be necessary in most cases. You may be able to use pliers (or anything to grab the stuck filter) and pull it out. Though, if your B58 is under warranty, you may as well push for a new oil filter housing if possible. Why not? It’s worth a shot.
Replacing Disintegrated B58 Oil Filter
As mentioned, this shouldn’t be a huge deal in most cases. You should replace the B58 oil filter with every oil change, anyways. If you’re able to pull out the broken filter then inspect and clean any debris. Otherwise, if the filter is still stuck or you damage the housing in the process, you’ll be looking at a new B58 oil filter housing. Proceed with the oil change as normal. However, there is one more thing. We recommend changing the oil sooner after this occurs. This isn’t absolutely necessary but will help get any possible filter debris out of the oil.
Other B58 Oil Filter Notes
We’re interested to see if the B58 has common problems with the oil filter housing (OFH) and gasket (OFHG) in the future. The N54 and N55 are notorious for oil filter housing leaks. However, the B58 has a different OFH design. Nonetheless, we suspect the rubber gasket will be prone to degrading and leaking. Only time will tell how common this problem is on the B58.
B58 VANOS Solenoids
VANOS is BMW’s terminology for VVT, or variable valve timing. Ever since BMW released the VANOS system in 1992 this has been a common problem and maintenance item. Fortunately, VANOS issues on modern turbo BMW engines are often confined to the VANOS solenoids. Solenoids are relatively inexpensive and easy to replace. However, the is one catch on the B58.
The B58 timing chain was moved to the rear of the engine. Guess where the VANOS components reside? Right by the timing chain…at the back of the engine. So, we’ve got a bit of a headache here. Although, let’s put a rumor to death quickly. Replacing B58 VANOS components does NOT require lifting the engine. This is a misconception. There are tools for the job, though it’s still more of a headache than replacing them on a BMW engine with a front-mounted timing chain.
We’ve already seen some VANOS problems with the B58 engine. They are currently far and few between. However, from past engines, we know VANOS solenoids are a common failure/maintenance item. Be on the look-out for more of these issues to pop up in the coming years.
Symptoms of B58 VANOS Solenoid Failure
- Power loss/limp mode
- Engine hesitation and bogging, especially at lower RPM’s
- Rough idle
- VANOS fault codes
- Poor fuel efficiency
The above are common symptoms of B58 VANOS solenoid issues, but may not always point to a VANOS problem. Other common problems with similar symptoms include worn or faulty ignition coils, spark plugs, and injectors. However, fault codes will help point you in the right direction. VANOS solenoids may be considered a normal wear and tear item. Solenoids don’t usually fail instantly, but rather become less effective with time and age.
B58 VANOS Solenoid Replacement
The B58 uses two solenoids. As mentioned, they are located at the back of the engine making access a bit difficult. Although, VANOS work can be done without lifting the engine. Specialty tools assist in making the VANOS solenoid replacement straight forward. Expect B58 solenoid issues to arise around the 80,000-100,000 mile mark. However, you may make it well past without issues. Two of our N54’s are nearing 120,000 miles on original VANOS components.
BMW B58 Common Problems Summary
B58 coolant loss appears a common problem, but it seems minor in most cases. Don’t sweat it if you’re only topping up small amounts on occasion. However, it’s worth monitoring as the B58 ages. Disintegrated oil filters pop up frequently, but are not serious in most cases. Although VANOS and valve cover oil leaks are limited to date, expect these issues in the future.
As we stated early, it’s tough to say what problems may become common on the B58 with age. So far, it is proving to be a reliable engine and a definite improvement over the N54 and N55. A few recalls and service bulletins do exist for the B58. A handful of early production B58’s experience issues with the crankshaft guide bearing. Hardly worth mentioning as it is only a handful. Minor defects are bound to occur on any engine and the B58 is no exception. Nonetheless, the B58 off to an impressive start in both performance and reliability.
What are your thoughts and experience with the B58? Leave a comment and let us know.