The 5 Most Common BMW N55 Engine Problems – Failures & Performance Problems

N55 Common Engine & Reliability Problems

For those in the market looking to purchase a BMW 135i, 335i, or 535i one important aspect to consider is reliability. In this post, we intend to highlight the most common problems with the N55 platform; please keep in mind – this is not an exhaustive list of every single potential problem. All cars and engines will have problems at some point. Some problems are unique and only affect a small number of cars, while in this post, we will address the most common engine problems that affect a larger number of N55’s.

Common N55 Engine Problems

  • Valve Cover Oil Leak
  • Water Pump Failure
  • Leaking Oil Filter Housing Gasket
  • VANOS Solenoid Failure
  • High Pressure Fuel Pump Failure (HPFP) – Mostly older models

1. N55 Valve Cover/Valve Cover Gasket Oil Leak

Similar to the N54, a leaking valve cover, valve cover gasket, or PCV valve are among the most common problems with the BMW N55 engine. The rubber valve cover gasket is prone to degrading over time; typically rubber with high temperatures, and constant heating/ cooling do not mix well. Eventually, the rubber gasket begins to crack apart, resulting in oil leaks and potential build-up of oil in your engine.

Due to the relatively high operating temperatures of the N55 the valve cover develops similar issues. The valve cover is made of plastic and the high temperatures cause the valve cover to potentially develop cracks down the road. This is a less common issue than the valve cover gasket, and it will typically last closer to 100,000 miles (though this may vary significantly). However, due to the excessive labor required to access the valve cover gasket, it is highly recommended you replace the valve cover as well. Whenever you remove the valve cover you should always replace the valve cover gasket.

N55 Valve Cover and Gasket Leak Symptoms:

  • Low engine oil light
  • Burning oil smells, or smoke coming from valve cover area
  • Oil on spark plug threads

Another issue that ties into the valve cover and gasket is the Positive Crankcase Ventilation Valve (PCV valve). A PCV valve uses the engine vacuum to pull any blow-by gases out of the crankcase, and is integrated into the valve cover. Higher pressures and fatigue of the PCV valve lead to eventual failure, and this is a fairly common issue with the BMW N55. Due to the fact you must remove the valve cover and gasket to access the PCV valve you may want to consider replacing your valve cover, and as always, the valve cover gasket should be replaced. You can learn more about the PCV valve, and how to diagnose a failing PCV valve here:

http://www.e90post.com/forums/showthread.php?t=1197666

Replacing N55 Valve Cover and Gasket

As your valve cover, gasket, and PCV valve are all in the same area, if any one needs repair, it is never a bad idea to replace all three as preventative maintenance. The parts are relatively inexpensive compared to the labor required, and may prevent running into additional issues in the near future. Whenever the valve cover is removed you should always replace the valve cover gasket, even if it appears to be in good condition.

Should You Replace a Leaking Cover or Gasket?

This subject is up for debate. A minor leak from the valve cover and/or gasket does not cause any significant, immediate risk to performance or longevity of the N55. However, the oil may be leaking onto belts or engine and transmission mounts. Over-time this may cause these parts to wear down prematurely and lead to additional expenses. My 335i currently has 103k miles, and the valve cover gasket began leaking around 80k miles. Up until roughly 95,000 miles it was a relatively minor leak that was not dripping oil onto any engine parts, however, it has recently become worse. With that being said, replacing the valve cover, gasket, and PCV valve is next on my list of things to repair.

Replacement Cost: $389 for the valve cover, valve cover gasket, and hardware. Due to the intensive labor to access the valve cover, the cost of replacement at the dealer is roughly $1300 and $1000 at independent shops (this can vary quite a bit, however).

2011+ BMW N55 Valve Cover (includes gasket set)

BMW N55 Valve Cover Gasket

DIY Difficulty: Intermediate. This is not a complex DIY, but it does require removing a lot of parts to access. For an intermediate skilled DIY’er this can take up to 8 hours to complete.

DIY Guide: https://www.e90post.com/forums/showthread.php?t=1197637

2. N55 Water Pump Failure

Problems with water pumps do not only affect the N55, but are a widespread problem amongst most BWM engines. Water pumps are responsible for circulating coolant throughout the N55’s cooling system in order to cool engine temperatures. BMW uses electric pumps that are driven by a composite impeller, which do not have a very long lifespan. It is important to note – the thermostat is also a common point of failure. Due to the excessive labor to replace a water pump it is recommended you replace the thermostat along with the pump.

To reference our experiences with the N54 (same water pump) our 535i is on its third water pump; the original pump failed at 52k miles, and the second pump at 84k miles. The water pump in Jake’s 135i failed at 33k miles, while the pump on my 335i lasted until 95k miles. The longevity of these BMW water pumps may vary significantly, with failures commonly cited as early as 30-40k miles while others may last more than 120,000 miles. On average, if your original pump and thermostat last until 100,000 miles they are likely soon on their way out.

BMW water pumps typically do not show any symptoms before failure, but rather, fail quite suddenly. If the pump is slowly failing electrically, this can simply be tested by examining the coolant flow in the cooling system; a failing pump will not flow coolant at the intended pressure. The following signs may indicate your N55 water pump has failed.

Signs of N55 Water Pump Failure:

  • Engine overheating significantly – usually rapid over-heating once the pump fails
  • Cooling Fan running full speed (noisy)
  • Coolant boiling out of coolant cap

N55 CEL Codes for Failing Water Pump:

  • 2E81, 2E82, 2E83, 2E84, 2E85
  • 377A
  • Remember to check fuses

N55 Water Pump Replacement

Due to the rapid engine over-heating caused by a water pump failure it is important the water pump is replaced immediately, otherwise the car should not be driven. The OEM water pump is roughly $450, and installation will likely cost an additional ~$500. Replacing the water pump is not overly challenging, however, it is a time-consuming repair and it is important to properly bleed the cooling system afterwards.

Replacement Cost: $390-450 for water pump, ~$500 installation

Replacement Part for N55 E-Series: Water Pump for E-series N55

Replacement Part for N55 F-Series: Water Pump for F-Series N55

DIY Difficulty: Intermediate to Advanced

DIY Guide: BMW N54/N55 E-Series Electric Water Pump Replacement DIY (Video)

3. N55 Leaking Oil Filter Housing Gasket

Yet another weak point of the N55 is the Oil Filter Housing Gasket (OFHG), which begins to degrade and leak oil with age. An OFHG leak is not a severe problem in the short run, however, not to overly scare anyone, the oil commonly leaks onto the belt tensioner and drive belt. Oil dripping onto belts is never a good thing. This may lead to the belt snapping or slipping off the pulley, which can cause damage to other engine parts and, in the worst case, may even be pulled into the crankshaft seal (front main seal). If the belt makes it past the front main seal and into the engine internals you have a severe problem at hand. I don't intend to scare anyone with this information, as it's not common for the belt to be pulled into the N55 engine, but it IS possible.

This can all be avoided in most cases – of course there is the possibility of belts slipping or shredding for un-related reason – by simply replacing the oil filter housing gasket.

Additionally, if the OFHG leaks for a long period of time or leaks severely there is potential for cross-contamination of the oil and coolant. The Oil Filter Housing Gasket is roughly $15, so it is a cheap fix for something that may potentially lead to significant problems down the road. As with most BMW repairs, it can be a lengthy process to replace the OFHG, which means it may end up relatively expensive if you’re paying a mechanic. However, replacing the leaking gasket is important as it may help prevent issues down the road.

Replacement Cost: $10 for gasket, ~$400 for labor

Genuine BMW N55 Oil Filter Housing - Includes cap, filter, and gaskets (only for cars WITHOUT engine oil thermostat)

Genuine BMW N55 Oil Filter Housing W/ Oil Thermostat - Includes cap, filter, and gaskets (WITH oil thermostat)

N55 Oil Filter Housing Gasket Only

**We recommend replacing the entire oil filter housing, especially on N55's over 100,000 miles

DIY Difficulty: Intermediate – Roughly 4 hours labor

DIY Guide: http://f30.bimmerpost.com/forums/showthread.php?t=1372527 (F30 chassis)

http://www.e90post.com/forums/showthread.php?t=938455 (E9X chassis)

4. N55 VANOS Solenoid Failure

VANOS stands for Variable Camshaft Timing, which is a valve timing system used, in conjunction with Valvetronic, on the BMW N55 engine. To keep it short, BMW VANOS (or Double VANOS on the N55) adjusts the timing of the intake and exhaust camshafts based on the engine speed and throttle opening. The basic point of this system is to improve idling, smooth the power, and as the engine speed increases the double VANOS system boosts torque, increases fuel economy, and lowers emissions.

The VANOS Solenoids are always working, so they typically fail due to wear and tear and/or old-age. However, they may also become coated in oil and cause problems due to being too dirty or “gunked up”. It should also be noted – on early model N55 engines, between 2010 and 2012, the VANOS bolts were recalled. The bolts may potentially become loose or break; when the bolt breaks it typically drops into the engine oil pan leading to additional repair time and costs. As mentioned, this was recalled and should no longer be an issue.

N55 Failing VANOS Solenoid Symptoms:

  • Loss of Power and Torque
  • Engine hesitation and bogging
  • Rough idle, bouncing RPM’s
  • Starting issues and potential stalling of vehicle
  • Limp mode

The above symptoms are general and do not definitively point towards VANOS solenoids. For example, old spark plugs and/or ignition coils may cause similar issues such as loss of power, engine hesitation, and rough idle. The below check engine light codes may point directly towards the solenoids, however, a code is not always present.

N55 VANOS Solenoid CEL Codes:

  • 2A9A, 2A9B
  • 2A82, 2A98, 2A99, 2A87

Replacing Your N55 VANOS Solenoids

Some people elect to simply clean the VANOS Solenoids rather than replace them, which typically does not completely solve the problem but rather buys some extra time. The solenoids are not tough to remove and re-install, so attempting to clean gunked up solenoids may be worth the time. Although, the solenoids are not overly expensive, so replacing the solenoids is likely the best option if you’re looking for the most effective repair.

Replacement Cost: ~$165 for each solenoid (2 required), ~$200 labor

E-Series Replacement Solenoids: https://bmwsparkplugs.com/products/bmw-vanos-solenoid-11-36-7-585-425

F-Series Replacement Solenoids: https://bmwsparkplugs.com/products/bmw-vanos-solenoid-11-36-8-605-123

DIY Difficulty: Easy to Intermediate

DIY Guide: Please help us out if you find a good guide to replacing N55 solenoids!

5. N55 High Pressure Fuel Pump Failure (HPFP)

A high pressure fuel pump is tasked with the challenge of pumping fuel from the gas tank into the fuel injectors, where it is then sprayed directly into the cylinders via the N55’s direct injection. We will not spend too much time on this subject as it is primarily an issue with 2010 and early-mid 2011 model N55’s. BMW’s N54 is notorious for the countless HPFP issues experienced throughout its production. It was not until late 2011 that an effective HPFP finally solved the issue. You guessed it, despite countless attempts by BMW to fix the HPFP, in 2010 and 2011 when the N55 was first introduced BMW still did not have an official fix. So, the N55 was introduced with the same faulty HPFP as the N54.

However, unlike the N54’s HPFP which was granted a 10 year, 120,000 mile extended warranty, the N55 does NOT have an extended warranty on the HPFP. A majority of the faulty HPFP’s installed in early model N55’s likely failed under warranty and were replaced with the newest design that resolved the issues. There are still be some older N55’s out there running on the outdated HPFP, so this is something that may go wrong.

Bosch Replacement HPFP for BMW N55

N55 Reliability

Despite the many misconceptions that BMW’s as a whole are unreliable, the BMW N55 is actually a fairly reliable engine. The four most common problems with the N55 are, in no specific order, the valve cover and gasket, water pump, oil filter housing gasket, and VANOS solenoids. None of these are necessarily major issues, and most of the parts are not expensive. However, and I think this is where the misconceptions about BMW reliability come into play, the repair bills can begin to add up if you always service your car at the BMW dealership or independent repair shops.

Also, do keep in mind, this is not an exhaustive list of things that can go wrong with the N55, and simply because something is on the list does NOT mean it will indefinitely be an issue. With that being said, we are examining the “average” N55 and what goes wrong with the “average” engine. There are plenty of N55’s with 100,000 miles that have not cost a dime in out of pocket repairs, while others with significantly fewer miles may cost thousands a year in repairs. It all comes down to how well you maintain your N55, and to some extent, the luck of the draw. Overall, the BMW N55 is a reliable engine that can be easily tuned to make impressive horsepower and torque.

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49 thoughts shared

  1. 2015 X5 F15 N55 with 150K miles. No problems of any kind and no repairs. Plan to change the water pump just so I don’t get stuck in BFE

  2. Comment author image

    Michael C Bono

    says:

    Why do the high end of the prices quoted here seem to be about 50-66% of what I’ve paid at my local dealership. Water pump and tstat was 2800. Valve cover gasket w new cover was 1800-2000.

      1. Hi All, I have a 535i with 164k miles. Had jt for 6 years . ( totally stock) Over that time in terms of engine issues it’s had
        1 Message stating , engine will not restart after shutting down.( it didn’t re start initially) This eventually led to cutting out. The issue turned out to be due to the valvtronic system being out of range. It was fixed by Bmw by a software update. Though, the power delivery after this was much softer. ( possibly less of it)
        2. Message. Full power not available. This was due to tho boost control valve failing, allowing too much boost. Then causing derate. ( easy fix)
        3 oil leaks . Filter head & cooler at about 100k miles. – diy fix. Also, top cover. Did that at ~150k had been leaking for a while , started dripping on to down pipe.
        4. Coolant pump failure. – about 130k diy fix. Did the thermostat too.

        5. Wastegate rattle. This seemed to occur after I used BMw fuel additive. It eventually went away..

        The current status is that it purrs like a kitten but I’m not convinced it’s pulling full power. It could be that I’m just to familiar with it but it just seems that relatively normal cars can keep up with it.
        If I have low boost, would I get an error/ warning.
        I’m wondering if the actual wastegate valve could have fallen off ( hence the rattle stopping)
        It’s also very economical— 37mpg is common ( Uk gallons)

        Could vanos valve cleaning help ( there’s no warnings to suggest any issues there)

        All in all, a great car.

  3. Comment author image

    Matthew B ODonnell

    says:

    Hey guys,

    I suspect that the rod bearing problem is caused by too much load on the upper rod bearing under high turbo boost. i am fixing my first N 55 with spun bearings. The 3.0 is a little engine. (183) cu in. this engine produces 320HP. That is off the charts remarkable. But horse power has a price.

    Just my 2 cents.

    matt ODonnell

  4. Comment author image

    Conrad Frank

    says:

    I’m just going to add my spun-bearing experience here so someone can keep tabs how often this is happening! Like many others, changed my OFHG and within 1,000km, my engine seized. I had 108,000KM on the odometer. Very disappointed as I changed the valve cover, valve cover gasket and the OFHG all at the same time for around $2000. The 2012 X3 was a great car, but after this experience, I’m going to be hard-pressed to stick with BMW after being a loyal fan since I was a kid.

  5. Oh these N55 it’s like a slot machine it runs gd when u keep pouring money into it.
    It’s heart wrecking !it gave you goose bumps when all the fault lights pops up Within months after Spending your last Dollar.
    I think BMW engineers all of them should be fired

  6. Just get a fucking battery car, it’s faster and no engine. I have a BMW and I don’t know if I like it or not. It’s such a pain to maintain and think bout all the preventive maintenance but it’s beautiful and I am happy when it drive nice. With Electric, there is no stupid wait to get the engine warm up, which is stupid long with my inline 6.

  7. I was just told my engine developed a ticking sound because of a faulty valve in the oil filter housing. Supposed to be common but I can find no mention on the www. Is this baloney?

  8. Thanks for the feedback. I actually like wrenching on the weekends. I rarely take the car to a dealer. So gasket, valve cover, water pump, charge pipe I have the tools and knowledge to fix them.

    Car came back from the pre purchase inspection with a solid positive result, I asked about the leaks and gaskets, water pump, etc, and everything is actually fine.

    I’ll pick up the car Monday, followed by an oil change, filter l

  9. What are your thoughts on a 2012 335i RWD sport package with 50k miles on it. I am taking to a BMW shop for a inspection and safety. Asked price is 15k CAD around 12k USD. I road tested it and there is no sounds, weird idling, issues with drivetrain or anything else from what Ive noticed. I am aiming for longevity. I currently own a mustang ecoboost prone to blow up.

    1. Hi Bruno,

      If you’re planning to keep it stock or stick with light mods these N55’s can hold up for a long time internally. However, I would anticipate running into a handful of problems in the next 3-5 years or around 100,000+ miles. The top 4 problems we wrote about in this post are pretty common. One thing we missed in this post is the oil pan gasket. All of this stuff is pretty cheap if you DIY, but it can add up if you’re going to a shop.

      There are also a few other minor things that can pop up with age and mileage. Expansion tanks, coolant hoses, radiators, and charge pipes can and do crack sometimes. In essence, the N55 is pretty strong internally and should hold up for the long-term. However, it’s all the accessories around the engine that often run into problems and can add up quickly if you’re going to the dealer or repair shops.

      Best Regards,
      BMW Tuning

  10. A lot of great information on this site. Thanks
    I have a 2014 (Feb), 535i and it has been driving great and I do drive hard. I have put 121K miles on it and flawless performance and fun on the windy roads. So, far I have changed the vale cover gasket once and the radiator as it leaked once. Went through several sets of tires as I push it on windy roads.

    This one sometimes shakes for 5 to 15 sec on startup. Does anyone has any clue?
    Also, how do I find out if my car has the reliable fuel pump or same old bad one?

    It is not fun to loose either water or Fuel pump especially when you are on a long trip with your family on these cars; you will be stuck for days wherever you are for sure for many reasons. May be BMW with all the advanced technologies should figure out a way to detect the possible failures using the computers/sensors and let us know ahead of time.

  11. My first 335i drank oil by the gallon and my X3 35 engine had to be replaced with rod bearing, oh my zf8 had to be replaced as well. Don’t get me started on my dads X5 security…. 130i has been decent. Seriosly thinking of

  12. 2014 BMW 535i xdrive with 68k miles. Just had sudden failure of the valvetronic eccentric shaft and pump. Symptoms are an audible rattle upon approaching car when it wakes up. The car stumbles upon start up with heavy vibration like a bad misfire and returns a drivetrain malfunction warning and goes into limp mode. The labor intensive repair costs $3k.

  13. Comment author image

    Fayas Mansoor

    says:

    Hello, I have an f15 n55 2017 model. When I start the car after a day or after an overnight it starts and then drops off (like engine is not getting fuel may be), and then is alright in <2 seconds. Any idea why this is happening?

  14. I got a 435i X with 76000 miles MHD stage 1 stock internals. Driving it like I stole it and no issues at all. $0 out of pockets. The N55 sounds like new and the ZF8 is a beast. Super reliable.

  15. Took my 2014 535i XDrive in for scheduled maintenance (oil change, brake fluid flush) as I have an extended warranty. It has 87K miles and seemed to be running well. My service coordinator indicated he would have a few other items looked at and stated because of the age, there are about 3 areas where oil could be leaking. Long story short, there were issues/codes which came up concerning the intake camshaft. BMW of NA has now authorized my dealership to replace replace the engine at no cost due to potential metal shavings as a gear on the camshaft fell apart once the camshaft was removed.
    Am I simply fortunate this was handled this way?

  16. Great post, I came a cross it when I was looking to get back into the BMW game after I had my first E46 (loved this vehicle).
    At first I was looking into a 2008 550i with 96,000 miles on it, after some research and testing one out and doing a PPI in a reliable BMW shop in town, they suggested to stay away if I wanna save good money.
    I always liked the 3 series, since I had one, more sporty, more aggressive looking.. any ways, I found this 2011 BMW 335i with the M sport package that has 80,000 on the dash with a good service history…
    I’m so tempted to pull the trigger on it, man she’s gorgeous, but I really don’t want to buy a money pit..
    And there’s another 2011 328i with the M package with 101k on dash which looks good too, but it’s still a 328i..
    * wanna mention that I’m not looking to get any mods to the 335i other than Cold air intake, and maybe exhaust upgrade.

    What to do?..
    Any suggestions, ideas, recommendations?..
    What to look for?..

    1. As much as the 335m sport looks good ;it’s hard on your wallet if u can’t fix it yourself
      Water pump turbo (fuel pump oil filter housing )selonoids valv cover gaskets the list go on and on oil leaks on belts an d tensioner
      Unless u have a lot of money to burn don’t even go there
      Buy some other car

  17. Man I’m. Looking at a 2013 335xi coupe 6sp with 28,000 miles for $18k.
    It has an MDH 2+ tune, BMS intake, VrsF charge pipe and cat less down pipe. BC racing coil overs on 19” rims.
    It looks brand new, has a perfect set of tune options, black on black with a six speed and all wheel drive. Perfect for the NW,
    BUT
    now I’m Having flashbacks to my 330 CIE 46 coupe, and replacing the water pump 4 times, expansion chamber twice, oil leaks, radiator, hoses, belts, tensioners,. All the stuff that Works another on other car brands for ever.
    I really want this car, but now I’m having second thoughts. Seven years old was 28,000 miles, is a rare find, but I almost wish it had 60,000 miles on it while under warranty.
    Any thoughts????

    1. Hi TrevG,

      Sounds like a nice find. As you point out with your older E46, the N55 is prone to many of the same issues. Unfortunately, BMW cooling systems often have plenty of issues with age and mileage. While the low mileage is beneficial, age may sometimes have just as much of an affect on gaskets, rubber, plastic etc. Especially if a lot of the mileage was short trips; a lot of components wear down as they are continually subjected to heat changes.

      As the old adage goes – you have to pay to play. Or at least take the risk of paying. Some reliability comes down to how well the N55 was maintained while some comes down to the luck of the draw. That said, the N55 is an awesome performance engine and a reliability improvement over the older N54 engines. It’s also no Toyota, Nissan, Honda, etc from a reliability aspect. The average N55 is going to be less reliable than the average Honda. Though, the top 10% most reliable N55’s are likely better than the 10% least reliable Hondas. Some of that simply comes down to the luck of the draw.

      Best Regards,

      BMW Tuning

  18. Looking for answers I have a N55 with 125k on the vehicle. I recently had to replace all my plugs and coils due to numerous misfires. I’m going to remove and clean or replace my Vanos solenoids as it is an issue too (Coded PC13CO) for intake camshaft out of place. However in the meantime I have had to put two quarts of oil in the last twenty days and I have no idea where I’m losing oil at? I have no spots on my driveway or at work where I park it. I do not have any smoke coming out of the tail pipe (burning oil). Is this a possibility? Not that engine saavy but learning out of necessity. any ideas on where to look for this leak.

    1. Hi Robert,

      That does seem like an unusual amount of oil consumption for only 20 days. How many miles did you drive during that time period?

      Have you ever replaced the valve cover and/or valve cover gasket? Or the PCV valve? Valve cover/gasket leaks are common on the N55 and if you have never replaced it then it is likely leaking. Typically this oil drops onto hot components (such as the downpipe) and is burned up before it reaches the ground. Though this leak is typically not significant enough to cause as much oil loss as you are stating. The PCV system, when not functioning properly, can also cause excessive oil consumption.

      The intake camshaft out of place may potentially allow oil to pass the intake valves and enter the cylinder. This oil would be quickly burned up and likely lead to smoking exhaust.

      It is tough to say indefinitely. There are only a few places the oil can go. It is leaking from the engine, being burned by the engine, or pooling up in the intake piping. Given you’re not noticing significant amount of smoke or visible oil leaks I imagine it is a combination. You may have some minor oil leaks (valve cover/gasket, oil filter housing/gasket, and oil pan gasket are the common oil leaks) in additional to some oil being burned by the engine (possibly minor enough that there is minimal smoke, or it is smoking on acceleration or decel to the point you can’t notice). You may also have some oil pooling up in the intake piping.

      Sorry for the general answer without much insight. It is nearly impossible to say anything with certainty given the lack of evident symptoms. I’d start with cleaning or ideally replacing the vanos solenoids and go from there.

      https://bmwsparkplugs.com/collections/vanos-solenoids/products/bmw-vanos-solenoid-11-36-8-605-123

      Best Regards,

      BMW Tuning Team

  19. My BMW service tech reports that my 2014 335 turbo needs to be replaced. I asked him to investigate a clicking sound during “heavy” acceleration. I have 95K miles, fortunately I did purchase the 100K extended warranty. You guys knowing a lot more about the N55 that me, if you were in my situation, what else would you have replaced (at my cost). I have an opportunity here to save a LOT of labor hours. I am thinking water pump, but maybe there are other parts too. I have a good relationship with my BMW service team, but I would be interested to compare their advise to yours. Great CAR! Would LOVE to keep driving it for another 100K miles, especially since I recently — FINALLY — paid off the car loan..

  20. I have 2011 335ix. When car in park I push gas pedal to get tach to about 2000 rpm and I start hearing a rattle noise in engine Bay Area. If I leave off gas the rattle goes away and it idles great. Any ideas out there for this problem ?

    1. wastegate rattle is a common issue on n54 engines, in which the wastage arms that activate it would become loose over time. Not sure if this is an issue with the n55.

      1. Wastegate rattle at cold temps at first start up is normal too. It’s part of the cold start process. A slightly noisey wastegate isn’t necessarily an issue either.

    2. Hey Henry,
      Sounds very much like the belt tensioner. Look at the engine and let someone rev your car to 2,000 rpm and you will most likely see that it is the belt tensioner causing the rattle. I had the same. Replaced tensioner and belt and rattle gone.

      1. Well the n55 has finally done it. It has gone completely out. Less than 85000 miles. I am so angry at BMW and its corporate personnel. I will never buy another w and will let anyone who will listen to what happened to my car and a lot of other previous owners that Bmw cares nothing about. Apparently money to them is an after thought.

        1. Same happened to me. The engine locked on my 535i xdrive with 74,000 miles. BMW North America corporate had me get my vehicle history reports from my mechanic and then told me that they wouldn’t be able to assist me. BMW does not stand behind their product. I have told many of my friends not buy a BMW because they don’t value you as a customer. BMW is a joke.

  21. Don’t forget about the rod bearings they are a time bomb for the rods to go out and knock knock who’s there New Engine! It’s a big issue on n55 engines.

    1. Agreed! Mine spun a rod bearing and seized the engine at 140k. The replacement engine started knocking 8 months later. I found it too had failed a rod bearing, cracking the crankshaft.
      There needs to be more visibility on the N55 rod bearing issues. So many people get the wrong idea when articles like this tout reliability.
      My wife and I both drive Mercedes. BMW isn’t what it used to be.

      1. Hi Scott,

        Sorry to hear about your unfortunate experience with the N55. However, the rod bearing issues are completely blown out of proportion. The N52, N54, N55, and S55 all use the same exact rod bearings. Highly uncommon failures. Now, it does appear to be more common on the N55 than any of the other engines. Maybe there is some other design flaw or oiling issue on the N55. More likely, the N55s with issues suffered from poor oil quality, and poor oil change intervals.

        Failures occur with any engine, whether it be the N55, other BMW’s, or other brands. Suddenly, 20 people post on the internet and the issue gets blown up. We don’t hear the stories from the other 100,000+ N55 owners who have not experienced issues.

        Regards,

        BMW Tuning

        1. Hi BMW Tuning,

          Thanks for the quick reply and “condolences” 🙂

          I can only speak to the N55, as I have a set of failed rod bearings sitting here on my desk. But I would like to cover some issues with the rod bearing design.
          1) BMW-approved tolerances specify 0.001″ – 0.003″ diametrical bearing clearance. Optimal sizing for this size bearing is 0.0025″. This was confirmed by 2 N55 rebuilding specialists who offer “improve the bearing clearance to mitigate against spun bearing issues.” – MMP Engineering. Spun bearings are sensitive at the low end of BMW’s clearance tolerance.
          2) The bearing anti-rotation tab. Both bearing halves have tabs which are aligned to each other, meaning they hold against a “ramp” rather than a flat perpendicular surface. This is due to the fracture-split connecting rod design. Mercury Marine used the BMW I6 as inspiration for the Verado outboard. They also use fracture-split rods, but doubled the anti-rotation tabs. I think we understand why.
          3) The bearings are very small. Compare sizes to a typical 4.6l or 3.8l Ford, or even a Jaguar I6. I happen to have these handy, but all are much larger than BMW uses.

          Granted all these design differences result in higher fuel economy, lower frictional losses, and higher power density. But they only help if executed properly and robustly. Engine design is filled with compromise. Granted I only have 12 yrs in engine engineering, but I feel like they went too far in rod bearing design.
          Couple that with the very common OFHG failure. Didn’t re-prime the engine with oil? – Spun bearing. Wet belt slips off the crank pulley and gets debris past the crank seal and into the oil pump pickup? – Spun bearing. Poor oil quality or long change intervals? – Spun bearing.
          My point is, they can work but are not a robust design. You have to be super meticulous on maintenance and upkeep. Frankly, it’s like a hair trigger I wish to avoid.
          Now that N55s are gaining more miles and are out of warranty, I think we will hear about more rod bearing failures. Heck, it’s more than doubled since mine failed 2 years ago.

          Thanks,
          Scott

          1. You are not the only ones that is having various problems with the N55 engine .my 335 xdrive with only 90 thousand kilometres replaces radiator water pump and thermostat Vanos solenoids oil filter housing gasket spun bearing crankshaft knocking had to replace the engine
            All work was done by dealership the N55 is too costly to upkeepLeaves a big hole in your pocket not a gd volume for your money it’s disastrous to own.

  22. Have a 2011 BMW X3 XDRIVE35I (F25 N55). Have had to replace:
    Oil Filter Housing gaskets,
    valve cover and gasket,
    shredded engine belt.

    Still can’t find source of leak.

    Have elected to change the:
    Fuel pump (that sits under the rear passenger seat.)
    Spark plugs and coils
    Charge pipe (not long after tuning)

    Think I might change PCV, fuel injectors and Vanos out.

    Car has pretty rough idle at first, if I’m not careful, it will run the quarter mile without me, in the supermarket parking lot!! Can anyone help with ideas? Thanks, Tony!

  23. I’ve got a 2010 335i with n55 engine and it’s got 160,000 miles on the clock but runs and drives like a new car! Fingers crossed I can put many more miles on it and not have any serious issues!

    1. Rj – thanks for pointing this out, I may add it later on although this is primarily only a problem for modified cars running tuners and above stock levels of boost.

          1. Agreed! Hot weather climates on stock boost tho they’ve been known to collapse. Probably depends on how you drive it as well

            I’d probably just pick a charge pipe up from Burger Motor Sports. They are kinda a one stop shop for reliable tuning and boost.

        1. I just blew my chargepipe on 2012 335i 2dr n55 It has 35k miles and I just got it 4 days ago. I got on it pretty hard in second gear and heard something pop and drove fine but I had no boost. Parked it and checked out the next morning and saw the charge pipe snapped off

          1. What rpm’s were u at in 2nd gear when this happened? I’m looking at a stock 335i 2012 and the guy selling it said it’s ok 2 really push it in 2nd and 3rd gear. He said it’s really fun to hit 5-7 rpm’s, because the car really gets going and is such a rush to go over a hundert miles an hour in 3rd gear. I’m 18 and it’s my first BMW and I’m wondering what rpm’s you got that bad boy in 2nd and 3rd gear and is it ok on the engine? I know you blue the charge pipe, but I hear that happens all the time and aint a big deal. My boy said just buy a good one off eBay and it will be fine after that. He said the stock pipe gets real hot and busts easily, because it’s prolly plastic or somethin cheap like. I hope you got it fixed and you’re back to having fun. Yur car sounds great with only 35k miles. The one I’m looking at has 98k miles, but they guy said everything works great. He said he checked the codes or somethin and they are all good. He wants 19k 4 it, and I’m prolly gonna get it wensday or thursdy, because my girl is gonna loan me some jack and I guess I will try to get a loan from the bank 4 the rest. My credik is not too bad. Man I cant wait to get some good pulls on this bad boy. Thanx fur your help.

        1. Yep they’re made of cheap plastic aren’t they? This happened on my 2011 X3 35i 3.0L
          I believe they called it a Air intake hose. Ebay part T384RD.