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@cmt52663 I've got a new one for the thread. This may or may not be unique to the B46, and hopefully it doesn't come up for a lot of people.
At approximately 108500 miles (I am now over 125000), I found an unexpected oil leak at the bottom starter attachment bolt. The starter obviously doesn't have any oil in it, so this was a complete surprise. The note I made at the time was:
More dirt/gunk than oil, but definitely wet. The starter does not contain engine oil. However, the seam between the starter and engine block runs up to the top edge of the oil pan, where similar "unexpected dirt/gunk" was found. Not possible to see that top edge without a borescope/camera/other, but running a finger on that lip yielded a lot. Further towards front of engine, the oil pan does not have a lip and is clean, sealed with some sort of RTV/similar. Suspect top of the oil pan is leaking where it has an actual lip, which is towards the rear of the engine (left side of car). Top starter bolt also had "unexpected dirt/gunk" and is close to the oil pan lip.
I'll put photos I took at the time at the end of this post for reference.
Since then I have been watching this, and it has not gone away. I have asked a couple of trained BMW/MINI techs who opened their own shops about it, and their best guess was rear main seal or oil pan gasket. As the oil pan gasket is RTV, I really don't want to mess with that unless I have to, and about the only worse thing would be to deal with the cost and consequences of pulling the engine because "maybe" something is up with the rear main seal.
Whole lot of "ugh."
Well, I did an oil change yesterday and noted the same thing still going on. Also, the car is definitely consuming oil -- maybe 1/2 a liter within a 5000-mile window. Whether it is worsening or staying the same is tough to tell. But all that prompted me to Google up "b46 engine rear main seal." And wonder of wonders, courtesy of a Reddit discussion started in April 2023 and updated about 28 days ago, I got an answer -- a really unexpected one, yet to be confirmed on the B46 on my 2017 F56 S, but definitely a whopper of a find.
Links to the Reddit discussions (I'm including two, both started by the same user, because the photos in both are useful) below. Spoiler: the oil pan *itself* was leaking. Literal seepage through the pan. Rear main seal and oil pan gasket both dealt with and the leak continued, until the oil pan itself was replaced.
Reddit discussion 1, "B46 oil leak", in forum r/BmwTech: the first one I found, photo within shows the user's oil on starter bolt (exactly where I found and have been monitoring my leak). 19 August 2024 comment in the discussion from the original author says "The source of the leak in this post was oil seeping through the oil pan itself. I made another post about that. Replacing the oil pan stopped the leak."
Reddit discussion 2, "B46 oil pan leak", also in r/BmwTech: From the same user, more detail on the troubleshooting to ultimate resolution. The photo in the thread is with the engine out of the car, and the back of the oil pan wet with oil, apparently seeping through the oil pan itself. Disclose in this thread of the final fix being replacing the oil pan outright was 27 July 2024. The author went back and updated the other discussion with this resolution the following month.
End to end it took this person over a year to get root cause identified as the pan proper, with the oil pan gasket having been replaced in May 2023 and the rear main seal having been replaced in late October 2023.
The author also made this interesting comment with regard to the rear main seal proper (meaning dealer ability to get a new part): "They had trouble getting a new seal in the US that was not defective, according to them. They said all 3 seals that were acquired were not uniform either from manufacturing or shipping." That particular comment was from 4 October 2023.
I have never heard of leaking aluminum before, but they do get into that in the second discussion, with one person speculating that it might be a bad casting and another saying "I’ve seen this with ZF transmission cases seeping like that but not an oil pan. Still a cast piece of aluminum so it’s entirely possible. Of the thousand of B46/48 engines I’ve repaired and serviced I’ve never seen that."
For my part, I will probably wait until either BMW/MINI puts out a TSB about this or my leak gets worse. No point in tearing up the car in any way until there is either an acknowledged issue and tested fix, or it just becomes a "must handle now."
Fun one, this one. Figured this thread was a good place to document it. Pics of my own leak below, taken on the day I found the leak.
Last edited by cjv2; Sep 18, 2024 at 04:28 AM.
Reason: Add photos
I haven't posted in a long time, but figured I'd list my issues for potential high mileage buyers:
2014 F56S (B48) with 140,000 miles
My issues:
1. Failed front seat sunshade cover
2. Windshield wiper fluid reservoir leak
3. Sluggish acceleration sometimes (has happened since new). I recently replaced the spark plugs and mass airflow sensor, but it didn't help. I read there's an ECU update at the dealership, but I haven't scheduled it yet
4. I parked after a 500 mile drive last month. The next morning, it misfired on all cylinders after a cold start. I restarted the car and it's been running fine since then
Everything else has been working great, not bad for a first year model of the F56. This is my 5th Mini Cooper and they've always been a handful. Not as fun to drive as the previous generations, but it's easily been the most reliable
I haven't posted in a long time, but figured I'd list my issues for potential high mileage buyers:
2014 F56S (B48) with 140,000 miles
My issues:
1. Failed front seat sunshade cover
2. Windshield wiper fluid reservoir leak
3. Sluggish acceleration sometimes (has happened since new). I recently replaced the spark plugs and mass airflow sensor, but it didn't help. I read there's an ECU update at the dealership, but I haven't scheduled it yet
4. I parked after a 500 mile drive last month. The next morning, it misfired on all cylinders after a cold start. I restarted the car and it's been running fine since then
Everything else has been working great, not bad for a first year model of the F56. This is my 5th Mini Cooper and they've always been a handful. Not as fun to drive as the previous generations, but it's easily been the most reliable
There have definitely been software tweaks that include DME-side engine handling changes since my 2017 F56S (B46) was built in 10/2016 -- I had an update done a couple of years ago -- so stands to reason there is also stuff that applies to your 2014-vintage B48-carrying F56S. Very very interested in how the software update helps or doesn't help once you've got it done -- let us know when you have it scheduled and the result?
Let's not overlook the excellent info shared here - on Counter Balancer Cover Oil Leak that appeared for one owner at about 110k miles. Gollum hasn't seen that one... (yet).
This thread is getting kinda useful as folks pitch in - I am very pleased. CJv2 your post from the 16th might have saved be some coin! HERE.
FCP Euro just impressed me with their review of the B48 (B46) which taught be a bit I did not know!
HIGHLY recommended...
BTW Gollum is at 142k miles.
Cheers,
Charlie
That is a REALLY informative video. And I'm turning off my auto stop/start like right now. And it totally validated my not-so-wacko plan to replace every plastic cooling system component I can lay hands on, on a fixed interval. Wowzers.
Gollum is now at 167,000 miles (and change), and since replacing the oil cooler and water pump (the plastic silly bits on the front side of the block) we've had no issues worth fixing.
Issues NOT yet worth fixing include:
1. a minor seep from the plugs that secure the balance shafts
2. a proximity sensor that no longer hollers if I back up too far (video is fine)
3. corrosion on the hard line feeding the clutch slave cylinder
4. corrosion on a tiny braided cable that is part of the starter assembly, providing a ground
5. parking brake cables that cannot be relied on to fully release when the brake is disengaged
We'll take these as they become critical, as the total estimate to heal all of them is just over $5,000
Mileage is slightly off from 27.9 to 27.2, but winter does tend to use a bit more fuel.
Performance and reliability are still splendid, and Gollum is a rambunctious joy to drive when I tickle him.
Good to hear the little engine is still going strong. I’m working my way up there in the F60, likely to cross the 100k mark in the next month or so. I have an aluminum oil cooler housing and water outlet pipe sitting on the workbench, waiting. I’m contemplating changing out the thermostat “while I’m in there.”
I just crossed 116k and have to say that replacing the oil filter housing unit is the single most important item to address. It WILL fail, eventually. Mine was close to failure when I got it done a few thousand miles ago. My shop was impressed with the upgrade to the aluminum filter housing and connector pipe. https://www.northamericanmotoring.co...uto-trans.html
I just had Koni Special Actives installed all the way around. Oh boy, what a massive improvement in ride quality! Highly recommended, especially since the original shocks/struts had 115k on them. Even my wife noticed the massive ride quality improvement, which is saying a lot.
Next trip to the shop will be the water pump and possibly a walnut blast, if it even needs it. I'm seeing quite a bit of references to the B46 not exhibiting issues with carbon build up on the valves, or a least not as bad as the previous Mini engines. Easy enough for them to pull the intake and check it out though.
I have this post saved so I can keep track of the items that have been addressed here. Ultimately, I plan to drive this car as long as it will go and want all issue handled timely.
