BMW B58 Engine Problems

The 5 Most Common BMW B58 Engine Problems

About Zach Mayock - DieselIQ

Meet Zach

Zach is a BMW enthusiast with a passion for performance. With over 10 years of experience modifying and performing DIY work on BMWs, he’s developed a deep understanding of virtually every BMW engine. He’s also the proud owner of a 600whp N54 with upgraded twin turbos and an E30 325i drift car and has a particular affinity for the S58 engine. Zach is highly knowledgeable about all things BMW, but his expertise in tuning and performance mods sets him apart. His experience as an enthusiast, combined with his technical knowledge, makes him an essential resource for anyone looking to improve the performance of their BMW.

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.

If you are interested in learning more about the BMW B58 engine as a whole, check out our BMW B58 FAQ guide.

BMW B58 Engine
BMW 340i GT M Sport Estorilblau

BMW B58 vs B58TU1

Let’s examine the changes from the B58 to the B58TU1 before we dive into any B58 engine 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
  • Split-cooling
  • Crankcase re-design (crankshaft and walls)
  • Updated cylinder head with integrated manifold

If you would rather consume this content via a video, check out our BMW B58 Common Problems video below or on YouTube:

The 5 Most Common B58 Engine Problems

With the BMW B58 3.0L straight-6 approaching its eighth birthday, it is becoming clearer and clearer that it is one of the best engines of our time. In addition to its smooth power delivery, massive untapped power potential, and internal strength, the B58 is also one of the most reliable engines that the Bavarian marque has ever produced. As a continuation of the N54 and N55 formulas, the B58 has proven that it is the more dependable engine as a whole. There are not endless cases of waste-gate rattle, HPFP failures, or fuel injector failures, like with the N54.

With that being said, there are some shared issues between the three engines, like VANOS solenoid failure and oil filter issues. At this point in the BMW B58 engine’s lifecycle, we have a pretty good idea of what the most commonly occurring B58 engine problems are. In this guide, we’ll be covering the following B58 engine problems:

  • Coolant Consumption/Loss
  • Valve Cover Gasket
  • PCV Valve Failure
  • Oil Filter “Disintegrating”
  • VANOS Solenoids

We’ll break down these B58 engine 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.

1) B58 Engine Problems – B58 Coolant Loss

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.

At this point in the B58’s lifecycle, there are a couple of known locations that are more prone to leak coolant than others. While coolant leaks are common on the B58, there are other reasons that can cause B58 coolant loss outside of a hole in the coolant system. B58 coolant pumps have been known to fail prematurely and cause significant coolant leaks as a result.

Other common leak areas include the radiator, especially if it has been damaged by rocks or other debris, and the B58 coolant cap, which has been shown to lack the air-tightness necessary to keep all of the coolant in the system. Sometimes, B58 coolant loss can be dependent on other things as well. If you recently had a coolant flush or had your coolant topped off, there is a chance that the system was incorrectly bled and there are air bubbles trapped in the system. Here are a few symptoms and things to look out for if you’re losing coolant:

  • Water Pump Leak
  • Visible leaks / Intercooler Damage
  • Coolant tank cap

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 has been shown that the B58’s coolant tank cap has been the source of lost coolant for some owners.

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.

BMW B58 Water Pump Failure

Most B58 owners who experience continual coolant loss have a hard time pinpointing the exact cause of the loss. Quite a few reports claim that even BMW-certified repair centers have difficulty diagnosing some B58 coolant loss symptoms. Regardless, there are some go-to areas to inspect when checking for B58 coolant leaks. One of the most common leak locations is the water pump. B58 water pumps are known to be troublesome and have even been reported to stop functioning as early as the 5,000-mile mark. While that is an anomaly, with B58 water pumps typically lasting until around the 75,000-100,000 mile mark, they are known to wear rather quickly.

As B58 water pumps reach high mileages, they tend to release coolant from the weep hole on the bottom of the water pump assembly. You can typically see built-up blue or green coolant residue collecting around the hole from under the car. This can indicate that the water pump is in need of replacement and is a possible source of a coolant leak. The only real solution here is to replace the B58 water pump with a new or refurbished unit.

B58 Coolant Loss Fix

Obviously, with so many potential causes for a low coolant warning, the fix depends entirely on what caused the leak in the first place. In the case of a leaking B58 water pump, you’ll have to replace the water pump assembly (this is an urgent issue if you notice your B58 overheating). Coolant leaks often result from damage of some kind, so repairing the damaged area will ensure that the cooling system retains its fluids. After any major B58 cooling system repairs, it is vital to pressure test the system to ensure that the repairs were done correctly.

2) B58 Engine Problems – B58 Valve Cover Gasket (VCG)

Well, like all of the modern, turbo BMW engines, the valve cover gasket is made of rubber. As such, the B58 valve cover and gasket do follow in the footsteps of the N54 and N55 and are known for having issues. 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 is 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 are subjected to less drastic temperature changes. This does help a bit with longevity. With that being said, it doesn’t totally eliminate valve cover gasket oil leaks, but it does 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

B58 Valve Cover Gasket Leak

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.

3) PCV Valve Failure

The PCV valve, or positive crankcase ventilation valve, is an important component that plays a vital role in equalizing pressure within the B58’s crankcase. Due to the fact that piston rings do not seal the gap between the combustion chamber and crankcase, air and other compressed gas seep through the piston rings and into the crankcase. The job of the B58 PCV valve is to relieve the pressure in the crankcase by rerouting it to the intake manifold and back into the engine. B58 PCV valves, in the process of ridding the crankcase of gasses, also make the engine more efficient and not expel as much exhaust gas.

Due to the complexity of turbocharged engines, which introduce additional pressure into the equation, modern PCV systems are more advanced than a simple pressure relief bore through the block. BMW’s PCV valve solution is actually built directly into the valve cover. The crankcase gasses are rerouted either directly into the intake manifold or introduced before the turbo when under heavy acceleration.

Where the gasses end up is dictated by a diaphragm in the PCV system. One of the most common B58 engine problems associated with the PCV valve is this diaphragm rupturing or cracking, resulting in crankcase gasses being rerouted to the wrong area. This can result in oil-rich gasses being pumped into the intake manifold.

BMW B58 PCV Valve Failure Symptoms

  • Smoke coming from the exhaust
  • Timing issues
  • Engine running either lean or rich
  • New or worsening oil consumption
  • Poor engine performance

When your BMW B58’s PCV valve fails, or is nearing failure, one of the most common symptoms is smoke coming from your exhaust. There are countless videos of B58 BMW owners with this exact symptom resulting from a damaged PCV. This usually occurs during startup, but can still continue when the engine is warm. Excessive oil consumption is another big one that can alert you to this issue. However, it can be hard to catch with this symptom alone, as the B58 also has other oil consumption issues.

BMW B58 PCV Valve Failure Fix

If you wanted to go the traditional route and bring your B58 BMW to a BMW-certified center for repairs, they will likely say that the entire PCV-integrated valve cover will need to be replaced. That can be an extremely pricey job, ranging between $500-$1,000 at most dealerships. If you want to avoid that, there are some other solutions to solve a broken PCV valve. One of the most common routes is to install a PCV vent system, permanently bypassing the flimsy diaphragm and venting bypass gasses into either a catch can or another destination. Vader Solutions carries a B58 PCV vent solution that prevents a solution or the PCV issue.

4) B58 Engine Problems – 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 can pull out the broken filter, 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 soon 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

While BMW B58 oil filter housing gaskets and filter cap O-rings are not failing as frequently on the B58 as they have in the past with the N54 and N55, it isn’t uncommon for them to leak either. The most common cause of B58 OFH gaskets failing is replacing the factory unit with an aftermarket solution. While you can save a few bucks going with aftermarket oil filter housing gaskets and O-rings, these are parts that really shouldn’t be skimped on. Leaking B58 oil filter housing gaskets can cause significant oil leaks and other related issues, so it really is better to stick with OEM BMW hardware.

5) B58 Engine Problems – 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. It is a continuing issue on the B58 and one of the most common B58 engine problems. Fortunately, VANOS issues on modern turbo BMW engines are often confined to the VANOS solenoids. Solenoids are relatively inexpensive and easy to replace. However, there 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 seen some VANOS problems with the B58 engine. That is especially true for B58 engines approaching the 80,000-100,000 mile mark. 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 straightforward. 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. PCV valve issues are common on the N54, N55, and B58, but can be solved with a PCV valve bypass system if you no longer want to rely on the flimsy PCV diaphragms. 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, B58 engine problems are far less common than engine problems on BMW’s earlier turbocharged straight-6 engines. 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.

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  1. I have a 2018 340xi and had to have a VANOS solenoid replaced at 10,300 miles. The first indicator of an issue was a check engine light. A code scan revealed code P0012. BMW replaced it under warranty as one would expect. I’m not convinced there isn’t a secondary issue. The car seems to have lost some pep. Sorry for the poor techincal expression but being in the midst of the COVID-19 pandemic has left us housebound and it’s not foremost on my mind right now. I’ll take it up with the dealership once we are all in better times. Stay safe everyone!

    1. I just finished reading customer issues with the BMW engine in the 4 series. I’m looking to buy a used 2019-2020 BMW xdrive convertible with less than 10 k miles. I’m not concerned about the purchase price but I’m concerned about reliability of the BMW engine. Therefore, I will not purchase a BMW unless it is a certified BMW. Should I continue looking for a used BMW or
      perhaps look for a used Audi 4 wheel drive convertible. Your comments are welcomed.

  2. Hi Hank, I’ve currently been having issues with my M140i. I’ve had fuel injectors, coil packs and spark plugs changed. I’m not sure how many as I was never given any job sheets. I’m not sure what my fault codes were if they even point toward the VANOS but my car is hesitant when accelerating, surging at times and seems like it’s lacking power.. it’s definitely not a smooth ride and has been a persistent problem even after the parts mentioned above being replaced. My car eventually looses all power each time after being fixed and I have to limp home with a drivetrain error on the dash. Three times this has happened and I’ve only just reached 14500 miles.

    1. Hi Adam, Thanks for the information. I’ll try to describe what I suspect as a secondary issue. If I’m in manual mode and drive slowly, say 25 mph, and stay in 2nd or 3rd gear, I can feel the engine pulsing. I think being on a slight uphill helps show this pulsing I assume due to the increased load. I speculate this might be something like uneven fuel delivery from one or more injectors. It is subtle, I haven’t observed the tachometer following this pulsing. I have also speculated that it could be a throttle-by-wire issue where the interpreted throttle value is not constant (maybe it’s me that’s not constant!!). Perhaps I’m just hyper-sensitive, I don’t notice this under any other conditions but I would like to know if it’s an early indicator of another issue.. Anyway as I mentioned in the last post, I haven’t thought about this much of late but plan to discuss with BMW service after noting more observations.


      1. Hi Hank

        I’m experiencing the same as you when the car is under load. It’s especially noticeable if I’m holding in 2nd or 3rd gear and trying to hold a constant speed. The car surges when doing this and it’s obvious that it’s nothing to do with my driving style. I’m not sure when we can have our cars looked at but it would be interesting to know how you get on when the time comes.

        1. Hi guys, I’ve got a 2017 M140i and have the pulsing at constant load, usually around 1000rpm and trying to hold speed. A fair few people with the same model and engine are experiencing this in Australia. BMW techs don’t seem to know how to resolve this.

          1. My 2017 M240i with 27,000 kms is suffering from the same symptoms.
            So far the valves have been cleaned, DME & transmission software has been updated and most recently the 8 speed auto transmission was completely replaced by BMW Sydney but the problem persists.
            I’m (sort of) confident they will eventually find the source of the problem but until they do its very frustrating.
            Love the car but hate the pain!

          2. Guessing you are all semi-auto owners.. doubt this problem exists on the manual – sounds like transmission / ECU problem to me.. #

        2. Glad I wasn’t imagining this weird phenomenon 😂. Experience something very similar with a 2018 M240i. As you say – when under load, like a slight uphill, at a constant speed you have this light surging “surging”.

        3. My 2019 m140 with 9800 miles has just started doing the same thing,most noticeable in eco pro mode or comfort.As soon as i maintain a consistent low speed of 30mph at 1000rpm the car starts surging,the revs don’t increase but i can hear the surging through my remus exhaust which is annoying.
          Has anyone managed to get this problem sorted out yet?And if so could you let me know
          what it was please.

          1. Hi mate. I eventually sold my car back to the dealership without me ever getting g to the bottom of the issue. Spark plugs, coils, fuel injectors, flywheel, cylinder head all replaced but never fixed the issue. Washed my hands with it and looking forward to my next car (not BMW). Good luck with finding the issue with yours.

          2. Hi All
            My m140i has now been back to the dealers 3 times in the last 9 days.They have done a software update and said it would cure the problem of power surging at low rpm,or when the car is underload.
            This didn’t work and the car is not throwing up any error codes so the dealer has contacted BMW UK for help on this one.
            BMW UK’S reply was change valvetronics and re-programme.
            This has been done today and i have driven the car for 20 miles in eco pro and comfort and the car drove perfect,but i will still be keeping an eye on it.

          3. Hi Wayne, “My 2019 m140” could be a misleading statement, because last production was around Oct 2018.

    2. Hi mate,thanks for your reply.
      My car is going in to BMW on Thursday.
      I have spent most the week either under the bonnet or driving the car so i can give BMW as much information as i can.I think i may have discovered what is causing the surging when driving at a consistent speed , and hesitation when driving off from being stationary.
      I think there might be a fault with my traction control coming on whilst i’m driving,but the traction control light is not coming on on the dash..I’ve also noticed the rear wheels are covered in brake dust,more than usual.
      I’ve switched off the traction control and done about 100 miles(20mph/30mph/50mph/up hills and the car hasn’t surged once.
      hopefully BMW will sort this out.

      1. Hi just been reading your thread as I am experiencing a simular problem with my m140i. Did this fix the problem?

  3. I have a 440i with m performance and sound kit during cold start there is shaking in the car I can feel the shaking if I hold the stearing wheel with both of my hands I am not sure what might be causing the problem only have about 25k miles showed to dealer they dint find anything
    Im guessing something might be coming up in future Im not sure if any other b58 owners have this or if its common
    Other than that car runs like a beast, throttle response and driving is smooth love the pops from the m kit exhaust at 5k rpm they literally sound like gunshots

    1. nothing to worry about, the wastegate is open during cold start, and you have a more “free flowing” system because of MPPSK exhaust which has no resonator in the midpipe and bypasses the muffler with valves open (valves open during cold start and in sport modes)

      that’s why the car vibrates. If you get a downpipe and aftermarket tune you’ll definitely want to remove the cold start function. (cold start is just supposed to head up the catalytic filter in the downpipe, so that’s why it’s commonly removed after catless downpipe installation.)e

      Take care,
      @the340iguy on instagram

  4. Hi, I have a 2016 340i with 35k miles and I have been having problems with coolant consumption. At 28k miles I had a warning light – “low coolant”. I took my car to the dealership, they did pressure system check, but they didn’t find any leaks. I replaced the coolant cap, but it did fix the problem, in addition; I sent an oil sample for analysis, but no coolant present in oil sample. I add small amount of coolant from time to time, but nothing crazy. Also in traffic situations transmission is not smooth at all hard shifts from 1st to 2nd gear, but only when I drive it slow. other than that it runs good and I still like it.

  5. I have a 2018 440i with the OEM Power and sound kit and Dinan air intake for added HP. B58 engine is same used for for M4 with greater HP. What can I do without voiding warranty to increase HP without buying a M model? Thanks

  6. Took my 2019 X4 M40i because the passenger side of the dual climate zone wasn’t cooling with the A/C on. BMW tech found low coolant on the low pressure side. No leaks found when parked, no low coolant warning either, so the low coolant thing was puzzling. Turns out coolant was getting into the engine. BMW replacing whole engine with a new one.

  7. “Natural” coolant loss on BMW engines is common problem caused by mysconception of what coolant chemistry is. Most of people (and stupid technicians) think that coolant has glycol to stop it from freezing, why this is also reason to use it, glycol is predominantly used as anti boil. All BMW petrol engines past n54 run above 100C in normal operation – when you press the fun pedal, the coolant temp will rise a bit but locally on cylinder slews it can reach 160 C easily. Stupid technicians, or cheap skates that mix coolant with distilled water cause cooling system boiling point to fall. Original BMW coolant (the one in 1.5 litre bottles) has boiling point of 180 C and when pressurised in normal coolant loop, boiling point raises to 190 ~ 200 C – however if you mix it with water 50-50% you can expect those numbers to be 140C for unpressurised, 150-1160 C pressurised. Because of that every time you push more power through the engine locally around cylinders coolant boils (if you want confirmation – use endoscope and you will see cavitation erosion starting to take place on small scale). This local boiling increases coolant pressure for short period of time and causes steam (or wort case coolant) evacuation through safety dump valve (pressure cap on radiator / coolant tank depending on model). Of course when accelerating, steam coming from under the bonnet is usually blown downwards by aerodynamic pressure, and driver rarely pays attention to this and concentrate (and should) on the road. Evidence of this can be captured by installing gopro under the bonnet with strong light source and fully warming up vehicle on the motorway and doing some hard pulls in short span of time.

    1. Hi Tom,

      We appreciate the input and you bring up some potentially valid points. Yes, coolant lowers the freezing point and raises the boiling point. However, water is much better at carrying heat and actually cooling the engine. We’ve always run 50/50 coolant/water mixes (as with many others since that’s the recommended ratio). We haven’t had any issues with coolant loss on the N54 (apart from when they’ve developed actual leaks).

      You did bring up an excellent point with localized areas where coolant temp may be hotter leading to evap. Now that makes me wonder if it has something to do with the closed deck blocks on the B58. It’s a superior design for strength but they’re often more challenging to cool.

      Best Regards,

      1. Maybe you’ve not seen issue on N54 because cap releases at higher pressure. Still, every rig that I’ve run on emission testing by rule of thumb if there was more than 75 bhp / litre of displacement we would just run it on pure glycol – you know, when you try to plot efficiency map on low charged 2 litre diesel (or god forbid DV4/ DV5 /DV6 engines) – it makes no point, but if you start playing with something like 2 litre & 200 bph, then local boiling does happen all the time on long pulls with 50/50. Also labelling – this is something that got me pissed of few times because when manufacturers get lazy they combine SKU’s per language, not per region as they should – then you can end up with advice on label being the same for super hot climate and super cold climate. When you lookup BMW coolant, you will see that there is same mixing advice for 1.6 non charged 80bhp mini cooper for Canada region and M3 for UAE region.

        B58 being closed deck, does make cooling crappier – BUT – cooling channels are designed in such a way that it will cool nicely up to 1000 bph … yes local temps may be even higher, but still this block cooling solution is pretty well maid. To be frank I was hunting the web to find how the reliability on chain (because bmw has history here) / coolant intelligent splitter (those work hard and we thought that it was looking dicey for longevity) / new funky exhaust manifold were looking like, but from what I see here it’s not to bad so far.

        About heat capacity of water / glycol. Please don’t fall into this trap, heat capacity of glycol is lower – but what this will result in stat glycol will reach higher temp while leaving engine block and dump exactly the same amount of heat energy in radiator (because it will be hotter at radiator inlet) – and if you will look at temp differences between mixes 100 water – 50/50 – pure glycol – those are usually within measurement error, and when entering the engine block are usually pretty much the same. (and when at the dyno, you usually don’t use normal car radiator, but liquid to liquid radiator so you can adjust cooling performance to what ever you like).
        Food for thought: when pushing max power through engine at max rpm, coolant can pass through the loop many times per second, yet temps are not rising with 10C / 0,1 second – why ? Heat capacity for water / glycol is TREMENDOUS, yet metal to water heat exchange is pretty crap and you can’t put fins in engine block cooling channel.
        Yet when local boiling occurrs we were ended up with crap emissions due to increased combustion chamber temp ( and ECU will sometimes will try to mitigate that via increased pilot spray to cool down the chamber … funny those modern day ecu’s 😀 )

        Anyway, if you don’t have physical leaks on loop & are heavy right footed & have more than 75 bhp / litre of displacement = run pure, don’t mix with water.

        Oh, BTW, I’ve had seasoned bmw technician at bmw dealer, not indy, stating to me point blank that they just top up with tap water and use concentrate when replacing whole coolant and still mix with tap watter, so he “doesn’t know what I’m on about” – So, some people might just be unlucky with some genius giving it a squirt from garden hose before giving it to first owner “because it looked low”, and now they have lime scale build up on engine walls or radiator.

        1. Hello, I own F20 120i 2018 with B48 engine (184hp). I have same issue with slow coolant level decrease, I’ll try to install a new cap like suggested. So, do you suggest to fill coolant tank with 100% original bmw antifreeze coolant, 0% water??? Considered my car is stage 1 tuned. Thank you

          1. Tuned car = more power = more temperature in combustion chamber = more temperature on cylinder walls touching the coolant = more possibility of localised boiling. In normal condition like drawing to grocery and not even touching accelerator, you will never see this happening, but when doing hard acceleration because you want to get out of dodge, negotiate out of slip road and you need to rapidly gain 40mph, just having fun …
            AND BTW, I don’t know whenever new caps will fix anything. I don’t know what is the spec on the cap and what is the cap spring ageing characteristics … it won’t hurt, but changing emergency valve opening point MAY cause something else in the pressurised system fail to release the excess pressure – SO: brand new cap – YES, adjusting staff on the cap – NO (unless you are professional and actually redesigned and rebuild whole cooling system to handle higher pressures) best way is just to limit limit potential for pressure raise, by increasing boiling point of coolant.

    2. Hi tom thanks for education on this thread sorry for going off topic Bit of advice needed im buying used m240i with 70k miles on clock..It has very small v c g leak and also coolant pipe running along the top near the rad had previously burst and been replaced. should i stay away? or these are minor for this strong engine? Any input apreciated

      1. Ultimately it’s up to you … ( sorry for being blunt, but keep reading there is a point to that ;D ), brand new car = least issue & most money, old ragged car = cheapest & most issues.

        Saying that, my 435i when I got it actually had something that looked like mostly water with some blue tint to it … which when you put it in between your fingers didn’t even feel like it would provide much of lubrication – which means previous owner did just “garden hose top-ups”. I bought it at about 75k. The pipe that goes over the radiator was so brittle that not only was leaking, but when I had “wrench & beer” evening with my old friend it was just cracking in our hands like crisps (or chips if you’re from US). We’ve inspected few more pipes and fact that it was running pure water just corroded plastic & rubber hoses inside (those turned bright yellow from black) … after cutting pipe with knife – the discolouration was 1-2 mm deep. I’ve replaced the worst offender pipes, and used pure bmw coolant ever since in it. Car done 150k now, and pipes that I replaced are still right colour, original coolant pump still works OK and I have zero issues with overheating and coolant temp when idle fluctuates at 110 – 117 C. From what I’ve seen at the dyno where some inexperienced or “know better then the test schedule requirements” technician used pure water for cooling on endurance or long term emission tests, cooling pump seals and joint between shaft and plastic prop would fail first – but on my car it was not the case so far, so as usual “T&C applies, your milage may vary”.

        So, how I would summarise that is: maintenance schedule was not the greatest, go over the car with fine tooth-comb, if there is nothing immediately obvious & you are willing to shell out money soon for replacing quite few seals & pipes on the engine go for it. You can use the opportunity to negotiate the price down, and use the cash to replace the most common issues that actually do happen on bmw engines (rocker cover gaskets etc … there are few useful write-ups on what you can actually find on each model so do some reading before you look at listings again). Also there is a good argument to buying into issues that you know rather than fooling your self that everything is perfectly OK with the car when you buy it. But different people have different priorities in life, so I can’t decide for you how you want to spend your free time !

        Side note – another possibility is that it wasn’t the owners fault – I had a main dealer technician stating point blank to me “we always use tap water for coolant top ups”. Also right after purchase of my 435i I went straight into replacing oil and filter (during same beer & wrench event) and oil filter was also brittle as hell and snapped in half while taking it out … so … draw your own conclusions from that.

        1. Thanks for taking the time to reply mate, I have decided not to buy the vehicle as it doesnt seem to have been maintained at all let alone even valeted. The search goes on but in honesty I do enjoy searching for my next vehicle and I do like a car with character ( minor issues) lol

  8. Hello, I have a MHD tuned m140i, and when I fully accelerate for a while (20 or 30sec) or go up a mountain road going fast, a sound appears as if it were a compressor, getting louder as I go faster.
    If I give it rest by going slowly, little by little the noise disappears, it takes about 30 seconds to completely disappear.

    Someone knows what is due? Has it happened to someone else?

    1. I have the same problem, in a 2017 bmw m240i, when I give it a spin and the vehicle is hot it sounds like it has a supercharger, or something that sounds like it doesn’t match the engine noise, then you release gas and it disappears

  9. Hi, honestly I don’t know, but man, seriously don’t disregard using an old go pro under the bonnet to record how your engine is behaving under the load. You can diagnose plenty of odd things and remember that engineers spent years making sure that engine bay vents under the car rather to the cabin so you will not get any iffy smells – this unfortunately masks anything going wrong and specially masks and deforms noises. You can get old one with slowmo (really helps) for about 100 quid. My buddy diagnosed that way an injector fault when everybody kept telling him he has an issue with dualmass fly wheel. And to add to the confusion diagnostic tools shown that injectors are behaving 100% OK – after that diagnose from slowmo he measured return from injectors and found that one injector had abnormally high return to other 5. After replacing it he enjoys the car again and issue is rectified.
    Soooo if you have some noise under load – best record it from engine bay. Change places of where your camera is so you can better locate it etc. It will save you tone of money in unnecessary repairs bills.

  10. I’ve had issues with my 2018 440i not idling correctly.
    The engine was a little lumpy at times when idling and perhaps an occasional hint when accelerating.
    After numerous visits to my local bmw dealer, it got a new engine.

  11. Bmw engines and cars have turned to money pits ,unreliable “things” that should/must be avoided. Only truly good engines bmw made were M20B20 series(2.0, 2.5 , 2.7) and the big sixes M30B35 along with all its smaller or bigger versions. The best one worth having and mentioned is S38B38 from the E34 M5 car. ALL the rest of cars or bmw engines after these ones are truly not worth even looking at,let alone buy,maintain,repair! It’s that sad with bmw. And for those with lots of money to spend there’s the Ford BARRA 4.0 straight six engine! Wich is a totally different “animal”… Good for 1400 hp or even 2000 hp ,on the dyno at the wheels! AND reliable!

  12. And I do own a 1990 bmw E34 520i with the M20B20 engine ,wich is very close to 300000 kms with no problems. Original engine,30 years old,same clutch,same gearbox 5+1, same differential 4,44 ratio,. I’m impressed to say the least. Even more so after reading so many comments here where almost new cars had to change engines…

    1. Seriously dude, I think you might be overreacting 300k is nothing. My history with bmw is:
      e92 – 168k miles (tune about 30% up)
      e91 – 189k miles
      f34 – 130k miles (tuned about 30% up – only intercooler upgraded)
      F11 – 151k miles (now only tuned by 30%, in the past was tuned onev 40%)
      my buddy still has:
      e46 – 380k miles
      e90 – 200k miles

      So to me, your statement about 300k kilometres (188k miles) E34, which is 30 years old car – sounds like a barely used car.

      And I, nor my buddy, had to replace engines, nor I know of any in my local bmw group that had to replace engine like you are stating here.

      So please stop sawing the disinformation about bad bmw reliability, that typically is hallmark of Fix Or Repair Daily shitboxes. Maybe FORD forums are for you?

      1. Hi Tom,

        Totally agree. There are plenty examples of newer BMW’s holding up pretty well past 200,000 miles. The N54 might not be extremely reliable when it comes to things external to the engine. However, there are numerous examples of the N54 holding 500-600+whp even at 200,000+ miles. And that’s the N54 which is regarded as one of the less reliable BMW engines.

        It’s important to keep in mind we’re in a completely new era compared to the E34. Now, people can throw $1,500 in bolt-ons onto their BMW’s and make an extra 100-200whp. It’s a lot of extra heat and stress on these engines. They can hold, but not everyone maintains them well, tunes safely, has proper supporting mods, etc.

        Best Regards,

        1. Zach,

          Engines now are far more reliable than in the past. Some just keep looking at the past with rose tinted glasses. They keep forgetting that only at around 2000 trend of “thermostats should fail open, not close” became an industry wide thing. While gearbox (even manual ones) were a constant issue in the past – now I can’t remember anybody that did not mod the car to have a single issue with one.

          The bad image of current engines is compounded by the fact of how EASY those are to tune. Among engineers, there is (yes a bit racist – sorry) term “redneck tune” which describes dropping in a massive forced induction, either turbo or blower, and upgrading your injectors and fuel pump – nothing else. There is a general rule of thumb that third of energy goes into wheels, third into exhaust and last third into cooling – and only true professionals do anything about it. Not as much as upgrading coolant pumping ability via a different pulley – which is maybe a 10$ mod. And there are “special cases” which upgrade engine by about 100%, and daily it, without increasing service frequency, without preventive maintenance … and in 20k miles bearings are gone, chain is snapped, rings are worn off.

          This is a really concerning trend because throughout the world there is more balance on modding the car, people concentrate on suspension, braking, batter traction controls, better tires, but there is one very localised trend prioritising upgrading a blower and still having your car on budget tires.

          ps. Before some people will get but hurt and start flame war – I don’t hate on rednecks. Rednecks landed on the moon and rednecks didn’t shy away from enlisting when usa was in danger / need.

          ps. 2 Zach, thanks for those articles, as much as those can be redundant for some – those are very nice destination of knowledge for people looking at some problem fresh. Don’t hesitate to pack those with even more detail !

        2. Zach

          About other part of your comment. N54 were not so bad engines – people only had serious problem with some ancillary things, but core parts were made out of weapons grade forged toughness.

          My regret (not even a problem) was that when moving from E to F, BMW matched gearboxes and diffs more closely to stock engine torques, which in my mind was a bit of step back, because you could always count on 3 things with BMW gearboxes in the past 1. they did not provided greatest feedback 2. they always had decent of headroom potential tune 3. every-time you changed gear you felt like you reloaded WW1 full caliber rifle.

  13. Our 440i is about 5 months old and has a little over 6000 Km. From day one of delivery, I have often smelled coolant. It seems the coolant loss has now accelerated. According to my best measure it is about 250ml/1000 Km. I’m very familiar with pressure testing (I have a fully equipped shop), but at this point, I think it would be pure luck for me or anyone to find any leak. The engine room is simply too full with views inaccessible. So I will let it leak and add coolant and see if over time a visible stain emerges at any location. Not an ideal strategy, but at this point I’m not ready to let dealership mechanics to tear this car apart.

  14. Luissays
    September 23, 2020 at 11:03 pm

    I have the same problem, in a 2017 bmw m240i, when I give it a spin and the vehicle is hot it sounds like it has a supercharger, or something that sounds like it doesn’t match the engine noise, then you release gas and it disappears

    Sounds like it’s the electric water/coolant pump for the turbo hot side maybe kicking in as under extreme load/stress.
    Check your turbo coolant level (smaller of the two reservoir caps)

  15. I too have had the coolant loss issue. when removing the reservoir cap, I noticed a bunch of “crustiness”. Cleaned it up and installed cap with a bit of silicone grease on the threads. Now I still experience a bit of coolant loss, but much, much less. The cap leaking does seem to be a part of the cause.

  16. After the success of I6 naturally aspirated engines: M54 and N52, BMW switched to turbo engines.
    Many issues with their turbo engines.
    Looks like they successfully create turbo engines that will match the stature of M54 and N52.

  17. the vanos solenoids were a 20min job with a cold engine. Just remove all the plastic covers and you can get your hand back there. The cost $60-$65 each and get a few spare clips. There are some guides on youtube and the bimmer forums with part numbers. Only tool I needed was a small flathead screwdriver. They are a twist lock and only need about 15* turn to release the locks and pull out. Space is very limited but its doable. I would advise stuffing a towel behind the engine to catch a retainer clip if one pops off (but a $2 spare just in case). I found remove driver side first. Then remove and replace passenger side. This helps with the length of the connector cable. Once the pass side is in and connected, install driver side and connect. Bam, 45min to an hour for the whole job. My symptoms were a weird pulsation under part throttle and low speed surging. On the forums you can see logs people recorded showing DME demand and the position feedback chasing it. It is usually just one of the sensors but I would do both anyway.

  18. This is a wonderful post – so clear and easy to follow. Thank you, Zach!
    But sometimes, my engine just doesn’t want to start. Could you give me some advice about this problem?
    Thanks for your help!

  19. Have a 2019 BMW 540i Xdrive that requires 16-32 oz. of coolant every twelve months, staring with first year. We ordered BMW, and leased it right from the assembly line. Vehicle was never abused, rarely driven beyond posted speed limit, but above coolant loss continued. No novice when it comes to engines, and would point out to BMW dealership maintenance manager there was white residue about coolant tank reservoir cap, indicating engine was possibly overheating, and causing reservoir cap to lift and discharge coolant. Although engine coolant light never illuminated indicating overheating, manager dismissed loss as normal. Don.t consider engine coolant loss normal, when all engine coolant systems are considered a closed loop. Additionally, no Japanese luxury car model I’ve owned over past three decades has ever lost coolant, and never had to add coolant, with exception of replacing coolant and allowing a day or two for burping coolant system. Quite annoyed at BMW’s cavalier attitude engine is perfectly normal, but are unable to offer specific reason for loss of coolant. This client will not be purchasing another BMW, back to Lexus, Infiniti and Acura, as their engines are trouble free well beyond 200K miles.

  20. I recently purchased a Pre-owned 2019 BMW 540ix with less than 28000 miles on it This vehicle drives like a dream My last SUV was a 2002 540ix with 254000 miles on it with no major engine/transmission problems when I sold it ,I did purchase it with 48000 miles on it my plan is to drive this vehicle 300000 miles or more

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