Are you ignoring something on your car right now? If it’s older, you probably are. Maintenance is simply a fact of older vehicle ownership, but like a toothache, the longer you put off that maintenance, the more painful it gets. Sure, you’re likely well aware of the lethal potential of failing wheel bearings and bad brakes, but sometimes a seemingly innocuous problem can lead to big troubles. Something as simple as a gasket, especially when it comes installed on say, a BMW.
Today, we’re talking about a problem that can afflict BMW N52, N54, N55, and S55 inline-six engines, but only if their owners wilfully ignore warning signs. It’s a problem that can be fixed for cheap early on, but once it comes to a headwind, it could leave owners with multi-thousand-dollar repair bills. All over a gasket that costs around $36.
To use a cartridge-style oil filter on these engines, BMW decided to go top-mounted, and top-mounting requires an oil filter housing. It’s a convenient thing most of the time, as the cartridge-style filter doesn’t trap used oil like canister filters do, and it makes it easy to inspect the filter media. However, there is a downside to BMW’s implementation here.
The filter housing requires a gasket, of course, and gaskets don’t last forever. So eventually, the oil filter housing gasket will start to weep. Once that weep becomes a drip, oil leaking past the top-mounted oil filter housing gasket can find its way onto the serpentine belt. Normally, when oil gets on a serpentine belt, it simply slides off and shreds, causing a mess and necessitating a tow, but not causing major damage. However, the clever engineers at BMW have found a second failure mode.
When the serpentine belt slides off, it can and very likely will go behind the crank pulley and wrap itself around the back side of the crank pulley bolt. From there, it can force its way into the front main seal of the engine and around the crankshaft, potentially causing engine-killing damage.
If a big enough chunk of belt slips its way through the front main seal and into the timing chain cover, it can get lodged in the timing chain, causing the engine to jump timing. Since this is an interference engine, by the powers invested in me, I now pronounce you piston and valve. You may now kiss the valve.
If this worst-case scenario happens to a BMW N52, N54, N55, or S55 inline-six found in almost every inline-six-powered BMW between 2006 and 2016, you will need to start shopping around for a new engine. Considering a new replacement S55 costs upwards of $22,000, this can be a seriously pricey proposition.
However, let’s say you do get lucky and don’t grenade your engine. Well, you’re still in for a world of financial pain, because although the parts are cheap, the labor is anything but. The front crankshaft seal itself is a three-hour job, and that’s just for inspection. If your belt made it past the front main seal, dropping the oil pan is a five-hour job on an F30 335i, and pulling the timing cover calls for 8.9 hours of labor. At the same time, you’ll still need to replace the leaky oil filter housing gasket, so tack a few hundred dollars in labor on top of the thousands spent fishing bits of belt out of the engine.
If you want a really good look at what can happen if the belt shreds on one of these engines, Charlie’s Foreign Car Service has the great Youtube video that I’ve embedded above. Note the sheer level of disassembly required to clean this mess up, along with the fact that even if your engine doesn’t jump timing, belt material can still find its way into the oil pickup tube, potentially clogging the tube, starving the engine of oil, and seizing the engine.
Perhaps unsurprisingly, this is a commonly reported issue in the BMW community, including reports of engine issues following a belt shredding, such as this forum thread on Bimmerpost:
Here’s an example of it happening on an expensive S55 M-car engine, courtesy of another Bimmerpost thread:
That’s belt material wrapped around a crank hub like seaweed. Terrifying stuff, and a seriously expensive issue to fix.
If you’ve replaced your belt and tensioner on schedule, this issue can be easily mitigated with a little vigilance, some cheap gaskets, and a few hundred dollars of labor. A new oil filter housing gasket is $35.99 from our friends at FCP Euro. That sort of money barely buys you a film screening ticket and popcorn these days.
Sure, not every engine will have this exact same ridiculous cascading failure mode, but deferred maintenance piles up. There’s no free lunch in vehicle ownership, you either pay now or pay more later. For everyone’s sake, if something is mechanically wrong with your ride, fix it ASAP. Chances are, you’ll be glad you did.
(Photo credits: BMW, eBay seller, Charlie’s Foreign Car Service/YouTube)
Support our mission of championing car culture by becoming an Official Autopian Member.
-
Here’s Why You Might Not Want To Buy A Third-Generation Toyota Prius
-
The Popular BMW B58 Inline-Six Engine Has One Big Achilles Heel
-
Here’s Why Busted Plastic Grille Flaps On A Newer Car Can Cause A Check Engine Light
-
If You Want To Buy A Cheap Jaguar, Here’s An Engine You Should Probably Avoid
-
Honda Pilots Only Just Stopped Featuring This Ancient Engine Technology That Most Cars Abandoned Over 50 Years Ago
Got a hot tip? Send it to us here. Or check out the stories on our homepage.
Maybe I missed it in the article, but how bad does the leak need to be? If it’s not leaving a puddle, almost no one will fix the leak.
Love hearing how BMW continues to come up with new and exciting ways to make their straight 6 unreliable, decade after decade. Happiest day was selling mine. No ragrets.
-previous N54 owner
BMWs are overengineered in the assumption that owners do their maintenance and NOT skip on them….and the electronics are a separate issue as well.
Moral of the story: If you think a BMW is a Lexus or a Cadillac in maintenance, YOU ARE WRONG.
“…BMWs are overengineered in the assumption that owners do their maintenance and NOT skip on them…“
I call bullshit on that one.
BMWs are engineered to last a standard US-spec lease without ruining the mothership in warranty coverage. A leaking oil filter housing will usually happen just out of warranty, and even if the regular BMW maintenance schedule is followed – it can ruin the belt and slip it in no time.
BMWs are engineered by commitee: some good team designs – sometimes – a bulletproof engine, then sends it to the next step to be covered in unnamable plastic junk which will fail.
Making something complex and advanced doesn’t make it overengineered. It makes it advanced and complex.And it makes it force the owner to open the hood and inspect things visually at every other gas fillup. Which gets us back to the 60s.
What you are describing is basically POOR maintenance coupled with HIGHLY complicated parts…..
I am no BMW loyalist, nor have I owned one..but that is ONE of the reasons keeping me away from BMW.
What I am describing is as far away as it can get from POOR maintenance. I’m puzzled that after all I wrote you can read it this way.
You can be religiously tight on your maintenance, get out of a $5k scheduled maintenance visit at your BMW dealership, get the leak to start two days later, and have the belt slip and get ingested in the engine three months or a few thousand miles after that, WAY before your next scheduled maintenance visit.
Maintenance can not catch an oil-leaking part that will make the belt slip and catastrophically destroy the engine BETWEEN regular maintenance intervals (which are getting more and more spaced nowadays per BMW’s own advice).
Dynamic maintenance reminders in the dashboard (on which most brands rely nowadays, BMW included) – will also NOT catch that.
What will catch it is scrupulous maintenance at intervals quite lower than what BMW recommends, plus paranoia. Which doesn’t rhyme with poor maintenance.
But if there is a leak, a simple inspection or just looking or hearing, or even seeing something not right can catch that? What I am meaning is AS thorough checking through the car engine and underneath as possible…
But there is the issue of complicated maintenance items….
A leak is usually visible, yes. But one has to pop the hood to see it.
And there we get into the other idiocy – most cars’ user manuals, to this day, would advise to “check the engine oil level every three gas tanks” or something along those lines.
On BMWs, we have been denied an oil dipstick for the last 20 years or so – replaced by some insane electronic monitoring. Which is another insanity for another rant. But it takes the excuse to pop the hood away.
So yes, one can monitor for such issues and address them on time – easilly, but NOT if simply following BMW’s recommended maintenance schedule.
You have a point there. And UNFORTUNATELY…RAM has done this. (I am pretty scared if the HDS recently shown will have this or a physical oil dipstick…). Now, if I had to take a guess, Ford would be the next in this for the 15th gen F 150…(hopefully not the SDs that follow).
I hardly see any old BMWs here in Qatar….but still see old Cadillacs from time to time.
Maintenance includes inspecting the car for small issues, then fixing them before they cause major issues. Maintenance is not just changing the oil! It is highly unlikely that this leak will get bad enough to lunch the belt unless it is ignored.
I own two N51/52 BMWs. One had this start to leak at 50K – that car spent it’s whole life in TX and FL baking in the heat. My other car lives in Maine and has no issues at the same miles. Both 2011s. The leak was easily visible, though minor, and it took me all of 45 minutes to change the gasket the next time I changed the oil. There really is no excuse, and in most cases on the BMW forums, the owners affected by this admitted to ignoring the leak. And inevitably the pictures show the front of the engine COVERED in oil.
Some people just need to stick to Corollas. <shrug> My 2011 e91 that I bought new has needed just a battery since the warranty ran out.
“Some people just need to stick to Corollas. ”
Good advice. Best to leave the BMWs for the fiscal masochists.
But is the chronic inspecting worth owning it? Does it fill the owner with joy that overshadows the underlying stress of “what could go wrong”? I love sporty, manual cars. I have been BMW curious for 25 years but I can’t rationalize the stress of owning one.
In my case, yes: it’s worth it.
Bought a high-mileage 98 M Roadster last June because it feels quick, the steering is almost telepathic, and the brakes are freaking phenomenal. I spun the oil pump nut off in late January. Spent 80% of what I paid for it to put in a motor with 1/2 the mileage, clutch, all the ‘while I’m there’, etc. So, I have about twice what it’s worth in it—but I don’t regret it at all. It makes me smile, and giggle—and sometimes shriek a bit in alarm.
But, I don’t have to commute in it; that would change the equation quite a bit
I think the bigger point Goblin is some others were trying to make is, this is an inherently flawed design. In the oil filter gasket, and in the design that allows the belt to be ingested into the engine. BMW could easily implement changes that would prevent this issue in at least three different ways. In the year 2024 no oil filter gasket should be leaking after such a brief period. That is poor engineering. Either in the physical design of the gasket or in the materials, likely the latter.
The layout that allows oil to leak onto a mission critical part is poor design.
The path the belt takes upon failure is poor design.
“Be better at maintenance or get a Corrolla!” is not a good defense of bad engine design.
BMW should be held more accountable by their customer base.
My car is 13 years old and the gasket isn’t leaking. My other car was 10 years old, and it had JUST started – probably would have been a year or two before it would have been noticeable but I changed it preemptively. How long a life is acceptable to you? I will grant that they should have fitted the shield for the belt, but people should also inspect and fix their damned cars. It has to get pretty bad before the belt will come off. It’s not a subtle failure.
BMW has long since changed the gasket material. But this is an issue that takes a good 10 years to manifest – these cars were out of production by the time it because a really common issue.
At the end of the day, everything is a compromise. The cars are expensive enough as it is, build them to last 100 years and nobody can afford them. Fix the issues, enjoy the car. Or buy a Corolla.
Yeah that’s what confuses me here. Part of the maintenance schedule and dynamic indicators is literally “inspect the goddamn car”. People are equating “maintenance schedule” to “here is an excel spreadsheet that tells you exactly what parts to replace and when to replace them” which is just… not a thing.
As for engineering for the warranty period, unfortunately that seems to be exactly what post-E46 BMW is all about. Building cars for leasees and nobody else because they discovered that’s where the money is.
That said, the N52 is possibly one of the best modern enthusiast engines ever made. In *30i trim it makes 255hp and revs to 7,000 RPM with a simply addictive delivery of power and still manages upper 20s in fuel economy on the highway while still being a naturally aspirated, port injected, engine and shockingly easy to work on (especially compared to its weirdly more popular predecessor the M54)
“If you think a BMW is as good as or better than a Lexus or a Cadillac
in maintenance, YOU ARE WRONG.”There… fixed it for accuracy. LOL
“but like a toothache”
Oh yeah, like David’s joke about how he goes to the dentist at 2:30 since his “tooth-hurty”
Mmmmm here come the armchair engineers. I refuse to accept N52 slander. Fix oil leaks. Maintain your cars.
Wire your oil pump nut.
That’s an M54 issue. I haven’t heard of anybody having issues with that on an N52.
<raises hand>
98 M Roadster with 180k S52. I knew about it—could have easily done it in a weekend for about $350 including the support & oil change—but have gotten to the point I enjoy driving more than wrenching. So I spun it off doing circle work somewhere I didn’t have cell service—and definitely couldn’t leave it with the marks there. Idled it off the mountain, and it died backing into a parking space.
I did wire the nut in the 90k engine I dropped in. Lesson learned.
(after writing this, I focused a bit more & realized you wrote N and not S. Dagnabit!)
That’s a heartbreaking story though 🙁 RIP S52
Oh, it’ll live to turn tires in anger: we posted it cheap on a board, and a member of a racing team drove up to get it. I was totally honest about it, and they were happy to get it: best outcome I could have given I don’t have a garage to rebuild it in.
Just don’t buy a car with a poor design. Now if a gasket is too leak design it so the leak is captured and the oil is fed back into the engine.
A bit misleading to put the price of the gasket in the title, but not the price of the work involved.
There are two gaskets that can fail – the usual “easy” one, but also the one at the base of the oil filter housing.
If the one at the base goes, it pisses oil just as beautifully as the other one, but replacing it is fun till you get 90% into the disassembly and realize that 80% of the BMWs sold in the US are AWD models, and that for those you have to usually add a “If you have an AWD one, add 2 hours of labor here” – as that very last bolt requires to take the intake off.
Also, another (easier to fix but more expensive) oil-pissing source are the two hoses that go from that oil filter housing to the oil cooler. They are rubber hoses, they cost $120 a pop in good OEM but not genuine BMW version, BMW ones are more like $160 a pop, so eventually everyone goes with Chinesium or URO ones which have to be kept in check.
And that’s why you reassemble this with a VTT crank seal guard – usually too late.
^THIS^
Yup. Can confirm this is an issue. My oil filter housing weeped a bit of oil but no oil ever onto the belt. Until. It. Did. That was at 125,000 miles. Of all the things that went wrong over the years with my E91 this was one of the LEAST problematic issues.
I’m not sure why we accept that actual-supposed good cars have issues like this.
Are you creeping our Discord conversations???
I’ve got an N52. I’ve done this exact gasket, twice. I, personally, would recommend every 70,000 miles, MAXIMUM!!!! Don’t go longer, it will fail, and you could get this failure. Mine nearly hit the 70k milage exactly. So, I would even recommend every 60k. This past failure completely drowned the whole front of the motor with oil and grime. I waited too long, and it took me forever to clean it all up. I got VERY lucky in that mine did not swallow the belt. My wife even drove home from the local stores with it dangling.
While I have kinda come to hate this motor a little bit, I love it more than I hate it. The electric water pump allows one to drive with the serpentine fully removed, but the motor will not overheat (as long as you have battery). So, for a short local trip home, as long as the serp is clear of stuff, you’ll be fine.
I just did my second one this past winter vacation. I also replaced the front main seal for good measure. I also replaced every cooling system component. This cost me about $1500 from FCP, and I did my own work.
My car is around 177k miles. It’s a good piece of mind, if you are anywhere near this mileage, get ahead of it, lest you will regret it. BMW’s are notorious regret machines. Stay ahead of them, and you should be a happy owner.
I’ve got a 2014 335ix GT and knew this was pretty much the one Achilles heel, and after googling how to do it yourself, I did just that a couple years ago. It was definitely intermediate wrenching stuff but nothing needing a lift or crazy special tools.
Fantastic engine otherwise, pulls like there are more foot lbs and horses in there than advertised. Only paid a shop to do the alignment so far in 60k miles ownership.
As soon as I read the title, I knew this was going to be about the N52 and other related engines. Btw, a leaking valve cover gasket cal cause the same problem. The OFHG is just in a better place to saturate the serpentine belt with only a small leak.
It seems irresponsible not to mention that you can install a crank guard for like $40, which will prevent this from ever happening. It takes all of 30 minutes to install. And then of course, if you simply keep up on your maintenance and don’t let a leaking OFHG get out of control, your engine will also be fine.
Crank guard??? I’m buying one this weekend. I’ll be in there doing the DISA valves anyway. Thanks for the heads up!!!!!
Yeah, there are some fancy companies that will charge you $$$ for their brand name, and ones on Amazon that do the exact same thing. It’s a piece of metal that prevents the belt from going through the front crank seal so it isn’t complicated.
Glad I gave you the idea and good luck with the DISA valves! Pulling the IM on the N52 is much easier than its predecessors.
Given the abundant reports of cheap clone guards breaking, vibrating or rubbing & not fitting well, the one “fancy” guard is usually the one to get. Starts with a V, ends with a TT. They are the ones who launched it.
Thank you for the tip! The ones I was looking at on Amazon all had good reviews, but there are a lot of fake or sponsored reviews out there. I’m not too worried about this issue in my N52 as it is not leaking oil from anywhere.
My 50 year old BMW bavaria has an oil cannister and it magically doesn’t leak. And it wouldn’t matter if it did.
I see this usually a couple times a year and call it “slurping the forbidden spaghetti.” In many cases, the cost of the repair will exceed the value of the vehicle. On occasion the customer will still want to do it the spaghetti removal surgery and in those cases I always recommend selling the car immediately after repair as in all likelihood, there will still be tiny bits of belt still in there and as stated, up the oil pick-up it goes and sadness ensues.
I legitimately laughed out loud at the “slurping the forbidden spaghetti” part. Thanks, I needed that.
Now where would you say David’s shower spaghetti falls on the forbidden scale?
I would call that semi-acceptable, like a shower beer but less convenient. At least it’s digestible.
Shower beer is excellent but shower spaghetti is a cry for help.
Point 9562 of why I will not own a BMW. I love how they drive and I get the appreciation of the make. However, the over complication of German engineering to a fault turns me off.
Exactly. Every time I worked on my B5 S4 I cursed the German sobs that designed it. Complicated for complicated sake.
I had a B5, and upgraded to an 06 530 with this motor. Similar feelings, but WAY less hatred. I will never regret letting my B5 go. I’m still on the fence about this one, though.
Concur. My experience with BMW, fun cars but fragile, over complicated and designed in cascading failure modes. Life is too short and my money is too valuable for the grief associated with this brand.
I would say even Cadillac is easier to repair than BMW with the exceptions of some engines (eg: Northstar, 3,6L etc)…
That is why I see older Escalades still here in Qatar…but not many BMWs….
Given the TFTS and your intro, you missed out on a really good opportunity to publish at 2:30 to make DT happy.
German engineering at work: let’s solve a problem that doesn’t exist, and make things even more complicated.