Since November, my wife and I have been scratching our heads and giving ourselves headaches about our 2001 BMW 525iT. The stately wagon that we purchased from the Bishop seemingly overnight developed an unquenchable thirst for oil. Then it began misfiring on multiple cylinders. It got so bad that it burned a quart every 50 miles. Mechanics told me to prepare for an engine rebuild, but my wife and I didn’t need to go that far. I revived my wife’s car by beating the crap out of it and by replacing one little part almost everyone overlooked.
Last month, The Autopian’s full-time staff decided to rate our BMWs based on how much we regret buying them. Toward the bottom of the list, representing the most regret was Lewin Day’s basket case diesel 2008 BMW 320D and Sheryl’s wounded 5 Series, which smoked so bad you could have said it was a diesel. I bought my wife’s E39 in late 2020 from the Bishop, drove it around for a little bit, and then tossed Sheryl the keys. The BMW has been her most prized possession ever since.
Sheryl then proceeded to put about 30,000 miles on the car in less than a year. She made sure to keep up on oil changes and repaired little bits here and there as she went along. Sheryl also added small customizations to make the car her own, going as far as importing European market trim from Germany.
Then it all fell apart, as old German cars do…
What Happened
During my stint of ownership, I took note that the engine burned through about a quart of oil every 1,500 miles or so. That’s fine and manageable, so I instructed Sheryl to check her oil with regularity. The oil burn never got worse as she drove the car all over Illinois, Indiana, and Missouri.
Over this time, my wife replaced the car’s ignition coils and spark plugs. Other maintenance items included new brakes all around and new side mirror glass. When I bought the car from the Bishop, the ABS and traction control didn’t work either. Bishop replaced multiple wheel sensors without any luck. I figured out the issue to be an ABS module failure and that it was just blaming the innocent wheel sensors for its own wrongdoing. So, I had that part replaced, which turned off the so-called trifecta warning lights for the first time in several years.
These lights were so annoying!
The vehicle purred like a kitten and was officially in better condition than when I picked it up from the Bishop. Sure, we couldn’t fix the rocker rust, but this black wagon looked mean and drove with a purpose. We had it running so fine it even got over 30 mpg at extra-legal speeds.
Then late October rolled around and something changed about the car. Suddenly, fuel economy went into the toilet and oil consumption was best described as epic. I measured oil burn to be as much as a quart every 50 miles. My mechanic friends and even readers here suggested that there could have been a blown head gasket. But the car’s fluids never mixed and aside from the oil, they never changed their levels either. Yet the thick clouds of oily smoke billowing out of the tailpipe suggested the car was using oil worse than a two-stroke motorcycle.
Sadly, the BMW was Sheryl’s only car and she didn’t want to drive my cars, so she had no choice but to keep dumping oil in. She’s a lawyer and she will very quickly tell you “my BMW broke down” is not a valid excuse for not making it to court.
By November, things started getting dire as the M54 2.5 six signaled its displeasure with its existence and stopped running on one, sometimes two of its six cylinders. The misfires were constant and shook the car harder than a Harley-Davidson’s V-twin. From November forward, there was never a time when the car didn’t misfire.
While I know everything about Smarts and am gaining a great deal of knowledge about Volkswagens, BMWs are still relatively new to me. My experience and research with other cars pointed me to a bad Positive Crankcase Ventilation (PCV) valve. Let’s take a quick detour …
Not all of the gases produced by your engine leave via the exhaust pipe. Some blow-by gases slip past the piston rings and make it into the engine’s crankcase. The PCV valve has the important job of extracting those gases and re-routing them into the intake tract so that your engine can burn them. Reportedly, the PCV system as we know it was introduced in the 1960s as an emissions control. However, its origins date back to World War II when PCV systems kept engines sealed when trucks forded deep water.
Anyway, when your PCV fails the gases will likely find themselves unable to escape your crankcase. Those gases have to go somewhere and they’ll take the path of least resistance, slipping past the rings and seals to be burned by the engine. That alone is bad, but some mechanics also say that you’ll get sludge out of the other end, too, and that’s not good for your engine.
When Smarts get bad PCV valves, they tend to smoke, but they don’t burn a quart every 50 miles. Still, replacing a PCV valve is usually an easy and quick way to battle smoking problems. Note that I said “usually” there. See, while I could replace the PCV valve in a Volkswagen in 10 minutes or less, BMW’s gotta be weird with it.
BMW calls its system the Crankcase Ventilation system or CCV, and the end result is the same as PCV. The difference is that this isn’t a 10-minute job. Some searching revealed that someone with experience could do it in four hours. Amateurs would take longer if not a whole day. Additional troubleshooting revealed oil-fouled spark plugs. That’s not surprising considering all of the oil consumption. New plugs got fouled quickly, so that wasn’t going to make a difference.
Seeing as fixing this would be a big time and monetary investment, I wanted to be sure I was making the correct fix. Thankfully, I have a lot of certified mechanics as friends, so I started sending the car to them for first and second opinions. Most of them told Sheryl and me to prepare for an engine rebuild. While they all recognized that a failed CCV could cause smoking, none of them believed it would cause smoking and oil burn to the level they saw.
I mean, burning a quart every 50 miles means the oil is just slipping through every possible crack. One of our friends was adamant about a blown head gasket. Clearly, something else was going wrong in addition to the CCV.
The misfiring then got worse, forcing Sheryl to park the car. She then bought the Scion iQ which remains her daily driver today. I continued gathering mechanic friend opinions and all of them gave me bad news. I then tried a local shop and they concluded that they could fix the damage for $3,000 or so.
Eventually, Sheryl decided that repairing the rust for $5,000 and then paying another 3 large to fix the engine wasn’t worth it. You could get a rust-free E39 from the south for less than that! In April, she instructed me to take pictures of her car to prepare it for sale.
The Comeback
That day, I took the BMW out for my first spin in several months. Now, my wife and I have very different driving styles. I tend to redline every car I have on pretty much every drive. I love the exhilaration of using up everything my engine has to offer. Besides, the vast majority of the mechanics I’ve known over the years have told me that using up the tachometer helps the car “blow the cobwebs out,” so to speak. You and I also know of this as the slang term “Italian Tune Up.”
On the other hand, my wife drives for fuel economy. When she drives the BMW the tachometer usually stays on the lower end of the rev range. She rarely ever makes the car boogie.
Now, there has long been a lot of back and forth out there about the “Italian Tune Up.” Some say that working out your engine can blow out carbon deposits while others say it’s an old mechanic’s tale. It sounds like the most reasonable explanation comes from Engineering Explained.
Jason Fenske concludes that the proposed carbon-cleaning benefits of an Italian Tune Up are real, but you may have to really beat on the engine to see the benefits and it may not work for other engines.
Either way, when I hopped into the BMW I decided to give it one last thrash before sending it to a new home. Upon exiting my neighborhood, I put the pedal down. Four cylinders were reporting for duty and after an initial surge, the vehicle belched out enough thick oily smoke to compete with a steam locomotive. I then continued to keep my foot down throughout my final drive, making that injured car work. I wasn’t trying to fix anything! I was just trying to have one last gasp of fun.
20 or so minutes after I got my fill, I pulled into a parking lot to remove Sheryl’s stickers and to take pictures. When I was finished, I shut down the engine. The car’s battery showed no signs of life earlier in the day, so I wanted to see if it was brought back enough to start the car. Thankfully, the battery seemed to have been injured, but it wasn’t down for the count. It fired up the engine with gusto. Then, something unexpected happened. The constant misfire was gone. All six cylinders were firing without issue.
I called Sheryl and she was perhaps even more surprised than I was. She told me the car had been misfiring without a break since November. What changed? Well, this was the first time I drove her BMW since October, but that’s it. All I did was beat on the car, something she never does.
I decided to drive her car 50 miles. Sure enough, the misfiring didn’t come back. The car never stumbled, choked, or showed any signs that it’s been misfiring for months. Even the fat clouds of smoke that previously came out of the exhaust pipe were smaller poofs. It was clearly still burning a ton of oil, but it didn’t seem as bad anymore. The car didn’t even need a quart after my 50-mile drive.
Later, I pulled the plugs and they looked normal. Sure enough, stretching the engine’s legs seemed to have kept the combustion chamber cleaner. I’m still not entirely sure what happened, but my attempt to sell the car gave us a renewed determination to fix the vehicle.
For our next act, we contacted a BMW specialist friend and told him everything. Before we could even finish telling him what was going on he said we should replace that CCV. He was so confident that he didn’t even want to see the car.
So, fine, Sheryl bought an aftermarket CCV replacement kit. I contacted my trusty mobile mechanic, Jack at JET Mobile Auto Service. Yesterday, he replaced the CCV, commenting that the old one suffered from an internal failure. Sure enough, the old CCV was filled with gunk and was well past its prime. The manufacturing date on the old CCV suggests it was replaced about a decade ago. So this isn’t the original CCV, but it’s definitely old.
When I have more time I want to drill this thing out and see what the insides look like. For now, I’m just happy that replacing the CCV cured the car’s smoking issues. Seriously, I flogged the car hard down the road and not once did it let out any smoke. Today, Sheryl’s taking the car downstate and has reported no issues of any kind.
The car is even better than before, too. We had the catalytic converters replaced by a local muffler shop. Now, the car doesn’t have a check engine light on at all. Sheryl also reports that fuel economy has shot up to 40 mpg, but she will be sure to stretch the car’s legs more often than she did before. The Bishop tells us the dashboard hasn’t been this free of warning lights for over a decade.
The icing on the cake is a wild coincidence. Remember the car’s terrible rust? Just the other day I went to my mini warehouse to move motorcycles around when I noticed a few changes with the pickup truck customization shop right next door. It’s now under new ownership and is actively advertising rust repair. Sheryl and I thought sure, we might as well try. The business proprietor inspected the car and thinks he can rebuild the rockers with hand-formed steel for just $1,000. We’ll be on the hook for finding a rust-free tailgate, but $1,000 is way cheaper than any other quote we got.
The difference between him and those other shops? He runs a customization shop, not a body shop. So there’s no insurance work to get in the way. Is it a return of the $1,000 rust repairs that Bishop and I used to know of? We’ll find out.
Smooth Sailing, For Now
This car’s been through one heck of a ride. I was only hours from listing it for sale for Sheryl, now the car is mechanically fine. Hopefully, we’ll finally vanquish the rust, too. The best part? The smoke was extinguished for just $400. That’s parts and labor! The catalytic converters were $1,200 all-in. That’s $1,600 to fix what actual mechanics told us would cost thousands. It also took Jack about 4 hours to replace the CCV. It probably would have taken Sheryl and me far longer. I like to think of time as being like money, so $400 to save me from a ton of work feels like a good investment to me.
I suppose I have a couple of takeaways from this story. The first is that you should always consider more than just one opinion. Had we stuck to the idea that the engine needed a rebuild, we would have either unnecessarily paid the price or sold the vehicle. The reality was that the fix was much easier. Getting that third opinion was a game-changer.
My second takeaway is that it’s fine to trust yourself. I thought the CCV was a problem early on. Almost all of the symptoms were there. But, I began to fear that I’d waste time and money fixing something that wasn’t actually the problem.
Either way, I’m so happy to see my wife smile about her car again. She no longer regrets anything and will keep this BMW for as long as she can. As a bonus, having the Scion iQ around means she can drive the BMW for fun and not always for work. All of that is great. Long live Wanda the BMW!
Is that license plate a nerdy Star Trek reference…?
(…asks a nerd who recognizes it as a nerdy Start Trek reference…)
Could have just swapped in an M56 aluminum valve cover with the integrated CCV and you’d likely never have CCV issues again. You don’t even need to remove the old CCV stuff. Just put a cap on the dipstick tube where the factory CCV drains in so there’s no vacuum leak. The hour spent doing that would have solved the CCV issue and the tendency of the factory plastic valve cover to warp and leak.
Glad to hear its driving again! I had to replace the CCV system and all the hoses on my old E39 wagon. After so much time and miles, those plastic hoses start to give up causing all sorts of issues. The driving experience and utility almost make up for all the fiddling you have to do to keep these running.
When I got my e39 it had tons of problems. I’ve sorted them over the years. Best thing I have found for little money is this:
MoS2 Anti-Friction Engine Treatment (300ml Can) – Liqui Moly LM2009Highly recommend after an oil change. To keep these engines happy they need some high rpm romps to keep the VANOS system working well.
When presented with two possible fixes for a problem, always do the cheaper, easier one first. Although sometimes you get halfway through and realize that it wasn’t as much easier as you thought. 😉
I had two cars I drove that seemed to benefit from an “Italian tune-up” One was my ’03 Mini which I had to drive in stop and go a LOT before I went full-time remote. It was never in as poor of a case as this BMW, but yeah. The other was my friend’s Kia Soul bought used after having been 10 years old but very, very few miles, like 20K.
I love hearing things like this. Sreten would be proud of you.
That’s a hell of a deal on the metal work! I would have them or yourself coat the back with POR15 or something after, too.
I’m a big proponent of Italian tuneups. My engines tend to go longer with few to no problems, get better mileage, and on occasion, people with the same cars have commented about how they feel more powerful than theirs. Either I keep getting “ringers” or it’s the frequent Italian tuneups. Also, with two DI-only cars with close to or over 200k miles—one turbocharged—I never did any walnut blasting nonsense or any kind of “necessary” snake oil, or catch cans the people selling them insist the car will blow up without and never did I notice a loss of mileage (calculated at every fill up), drivability, or performance. I figure either the carbon build up issue didn’t apply to Ford (possible, especially considering the OEMs who built the notoriously problematic carbon build-up engines), the build up isn’t really a problem in terms of negative effects, or it was the Italian tuneups.
That’s fantastic, I’m glad it’s working out so well suddenly with the car. It’s definitely one of my favorites of your fleet, I’m glad it gets to stay in the family.
Interesting that the beat on it technique can actually work. When I was a kid we’d do it in our mom’s cars, while saying “Time to blow out the cobwebs!”, but it was always just an excuse to hoon. We had old school auto shop teachers that had mentioned the technique.
Funny enough, I gave my 4Runner the old Italian tuneup this morning on the way to work. It’s not something I normally do, but after being stuck in a line of cars yo-yo-ing between 50 and 60mph on the interstate in a 65, as soon as I had an opening in the left lane I floored it out of anger and wound it up to almost 90 to get by them all.
I always bag on the 4.0 for being a dog, and it is at low rpm, but when you floor it at 60 and wind it up to 5 grand, she really scoots for a V6 brick.
Such a great looking car. Glad you figured this out.
I make it a point to do this a couple times a year to any vehicle I own. I drive shorter distances and the car may sit a day or two at times.
So, I get it warmed up quite well first on a steady drive to one of the few places around here where you can safely, in local parlance, “beat the brakes” off the engine for a bit, then return to sane RPMs for a while to ensure no oil starvation issues. Repeat if you feel it’s warranted, or you just want to run the piss out of it.
I do this a couple times a year with my GDI Kia Sorento V6 (3.3L). So far so good, and it does seem to respond well to this treatment. It’s built more for luxury than carving curves, so this is a ponderous thing to drive at times (about 4400 lbs). But when that V6 decides to yawn and wake up, it has silly amounts of torque on the way to redline and a very satisfying throaty roar, instead of the embarrassing bovine sounds usually associated with a V6.
The only caveat I have is, some vehicles do NOT like this treatment. For instance, older Hyundai Delta V6 engines with variable valve timing respond poorly to being thrashed. The sudden drop in oil pressure after mashing the go pedal for a while makes the oil-charged VVT system do weird things. In my case, exploration of the redline in that particular vehicle resulted in expensive clunking sound thanks to a spun crank bearing and VVT servos that failed. Hyundai replaced the short block and related failed components. I didn’t try that a second time with that particular vehicle.
Great article, now I need to hear all about the Scion iQ or shall I say budget Aston Martin Cignet 🙂
Having spent nearly 20 years dealing with diesels sealed shut with emissions, my first thought was the crankcase ventilation system. Glad to see I was correct as the article continued.
My ’86 OM603 powered Mercedes (Garager parked, not a Streeter) had a drinking problem as well. with 313k miles on the odometer, a lot of things were suspected.
One known failure point is the PCV valve that’s integral to the aluminum valve cover and costs $600 to replace.
Since it always and forever fails in the open position, the enterprising individuals of the Benz forums found a solution.
The $15 PCV from a late 90s/early aughts TDI, along with it’s grommet, pop right into the valve cover where the original breather hose attached. I shortened the original hose and connected it up.
Now the drinking problem has resolved, it barely consumes any oil. I’ve added replacing the cheap part every couple of years as preventative maintenance.
Uhh, it’s an eye-talian tuneup, not Italian. Lol!
They all drive like that in Eye-taly.
“Sheryl also reports that fuel economy has shot up to 40 mpg”
obc must be off – m54s don’t get anywhere close to 40 mpg.
You have no idea how slow my wife drives. lol 🙂 Sorry, Sheryl!
sounds like someone i know. haha
on a more serious note: if your obc is reporting an accurate 40 mpg you are running dangerously lean – check first for vacuum leaks, very common on m54s.
the m54 is just not capable of achieving even close to 40 mpg in optimal running condition unless the driver is using advanced hyper-miling techniques.
– m54 owner and mechanic
I am so happy to hear that a beautiful BMW is getting a new lease on life. Did you write an article that goes into depth with the trifecta reversal procedure? I would love to have seen a deep dive into that.
My 03 Z4 has the same issue, I’ve replaced the wheel speed sensors and it worked for a little while and I’ve tried two different ABS modules, but the problems haven’t gone away.
The local shops are all quoting a few thousand dollars to fix, but as the car is so balanced and reliable in other ways, with some black tape over the dashboard, its like there are no issues. I have been fortunate and there hasn’t been any scary moments in the years its been without the safety features at least.
But I am a bit of a perfectionist and wish that it all worked like yours now does!
It’s been a while, but I recall using a diagnostic tool to confirm that the wheel sensors did work. I brought this up with a specialist and they concluded if the wheel sensors are actually working then the ABS module itself is likely faulty. We fished a module out of a junkyard, had the specialist code it to the car, and it didn’t work. We then tried a different used module, had it coded, and that one worked.
Thank you and Matt for your replies, I also have a high end diagnostic tool which shows the faults, and I now have 3 modules, and forgot which one is the original because they all don’t work! I think I need to have it coded, that probably the missing step. The fault appeared in 2017, and because I work overseas, it is just my summer vacation car. Since 2019, I have only driven it once last summer. so hopefully this summer when I go back home I can get it fixed with your method!
not the recomended way, but when I got my e39 I tried the hard smack method. Remove the module, be careful, there are actual springs in it. I let it sit on the bench overnight. Then picked it up, and smacked it firmly on my workbench, Installed and it has worked the past 30k miles without a problem.
Thanks for your reply! Between you, Mercedes and YouTube I am feeling confident I can finally get the car back to 100% during this summer vacation! (Being a teacher has its benefits)
Occasionally, the tone wheels on the half shafts and hubs get so rusty they deliver a faulty signal. If they are sketchy looking and the sensors are good, try cleaning the tone rings.
I appreciate the advice! I don’t think mine has that issue- my scan tool showed a fault in the module itself but it’s good to know what signs to look for