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New owner: Oil filter housing, fuel tank vent valve, engine mounts, & auto trans
Just bought a 2015 Mini Cooper S w/auto trans at 105k miles (for $9k) from a local small car lot. Leading up to buying and the couple weeks since I've been trolling the heck out of these forums and learned so much from the folks here. What an amazing place for information!
As I usually do any time I buy a used car, it went straight to my shop that specializes in higher performance vehicles and are OCD as hell down to the littlest detail. They do it by the book and able to fabricate, improvise, and engineer the crap out of any issues. That being said, I thought I would brain dump my experience with several of the common flaws and issues that are well documented here after getting the briefing from the shop a bit ago. Will be picking it up in a couple days.
- Oil filter housing: You ABSOLUTELY have to replace the garbage plastic housing with an aluminum one. I'm actually shocked based on every story I could find that this insanely poor engineering lasted 105k miles. Actually, shop said it was ever so slightly seeping coolant, which means it was only a matter of time before it stranded me. Thanks to all of the horror stories, I didn't even hesitate on this one and don't even care how much they are going to bill me. They mentioned that the seals were definitely on their way out and that the plastic was degraded (not failed yet) in the common place(s). I bought the aluminum oil filter housing replacement on Amazon as ECS didn't have it in stock (sorry ECS). Brand is Bomunik and while the shop said it was great quality, the mounting surface was not perfectly flat and true. It also didn't come with the gaskets/seals, which it was supposed to, nor did it have the "channel" to host the seals. They corrected the mounting surface flush mounted it to the block using permatex (prudently of course). From what they explained, this should be vastly superior to using the seals as there is no longer really any failure point since it's mated up directly (torqued to spec). I mean, why in sam hell would they use plastic for this purpose, especially given all of the issues? BMW seems to be purposefully creating a gigantic maintenance issue to generate future repair revenue. Any who, I feel much better about this solution and hope that's the end of it.
Edit (clarification/correction): When I talked to my guy at the shop in person there was some confusion on the oil filter housing versus the engine block connector pipe (also replaced plastic for aluminum). It was the engine block connector pipe (also Bomunik) that had the uneven mounting surface and needed planed then permatex, not the oil filter housing. The housing was good to go and they used the included seals, which they said looked like great quality also. Sorry for the confusion.
- Fuel tank vent valve: Sure enough this was the original valve and leaking, which was throwing the P0440 (Evaporative Emission System) code. Again, amazed that it wasn't an issue for the previous owner as it did pop the CEL on me a couple days after purchase. Dealer I bought it from cleared the codes 137 miles ago. Bastards! Any who, that should be good to go now for a bit with a new valve.
- Engine & trans mounts: Shop said they look absolutely fine which was a shocker. I hadn't experienced any knocking and such but expected them to be trashed, especially the upper mount. Not sure how the mounts have made it this far but luckily so far so good there. Will have to keep a close eye on this for sure.
- Auto trans service: There is absolutely no such thing as lifetime fluid, period. I have no way to know if the trans had ever been services but the shop said the fluid was definitely due (dark, dirty, and ready for a change). They drained and refilled 3 times (no filter change) and said it's nice and clean now, shifting perfectly. Folks, service your auto trans please. Heck, at least every 40-50k no matter what (maybe sooner?).
Everything else they said was is great shape including the valve cover (and PCV) and also said that I scored a really solid Mini. Next I'm thinking wheels, Borla exhaust, black out all the chrome, and maybe a few other little things.
With full confidence now I can motor on!! Hope this helps others!!
Last edited by 4merMarine; Jul 24, 2025 at 11:02 AM.
Reason: Correction
Good post and thanks for the detail about handling an aluminum replacement for the oil filter housing. I started what unexpectedly became a monster thread about that whole housing mess -- glad I contributed to the stack of knowledge -- but I had to replace mine at a point when an aluminum replacement was not procurable. Your details will help me out whenever it's time to replace the plastic replacement (aftermarket, Bremmen Parts/ECS Tuning), which I assume will happen not because Bremmen but because all plastic eventually fails. I definitely like the idea of sealing an aluminum replacement -- so long as it is good quality/machined properly, the next thing that always fails is o-rings and gaskets made of similar material so a sealant makes more sense.
I would love to know how your shop goes about checking the "health" (if you will) of the valve cover. People are still trying to figure out where on earth the PCV-equivalent is inside that thing (or outside that thing, or both, or whatever) and how to tell when to mess with it and how to properly care for it. It sounds like they know their stuff so I'm all ears.
Re the engine mounts: @Eddie07S put up a really good post in another thread (post #245) where he discussed what sounds like a pretty solid probability that the common failures of the upper engine mount are driven by failure/weakness of the lower engine mount (the "dogbone"). That could in turn lead one to proactively make some changes to the lower engine mount at least (such as a Powerflex bushing to replace the rubber in that lower mount). I'm thinking about doing this on my 2017 F56 S, having replaced the upper engine mount a couple of years ago and having 138K miles on the lower and transmission mounts.
@4merMarine - This looks like your first post here on NAM. Welcome to the MINI party…
Really good you have a shop that is knowledgeable and is willing to do this kind of work with aftermarket/non-OEM parts. Shops around me, at least those I have checked into, aren’t willing to do anything that isn’t OEM.
As for replacing the lower engine mount/stabilizer, it is an easy job and, at least on a manual, is well worth the change. Don’t know how much of a change you will notice with an automatic, but I really think it will play into saving that upper engine mount. If you change it out, let us know what you think of it.
Quick heads up. I had to edit a section in my original post for clarification purposes. Also here in case anyone is following. Cheers!
- Oil filter housing: You ABSOLUTELY have to replace the garbage plastic housing with an aluminum one. I'm actually shocked based on every story I could find that this insanely poor engineering lasted 105k miles. Actually, shop said it was ever so slightly seeping coolant, which means it was only a matter of time before it stranded me. Thanks to all of the horror stories, I didn't even hesitate on this one and don't even care how much they are going to bill me. They mentioned that the seals were definitely on their way out and that the plastic was degraded (not failed yet) in the common place(s). I bought the aluminum oil filter housing replacement on Amazon as ECS didn't have it in stock (sorry ECS). Brand is Bomunik and while the shop said it was great quality, the mounting surface was not perfectly flat and true. It also didn't come with the gaskets/seals, which it was supposed to, nor did it have the "channel" to host the seals. They corrected the mounting surface flush mounted it to the block using permatex (prudently of course). From what they explained, this should be vastly superior to using the seals as there is no longer really any failure point since it's mated up directly (torqued to spec). I mean, why in sam hell would they use plastic for this purpose, especially given all of the issues? BMW seems to be purposefully creating a gigantic maintenance issue to generate future repair revenue. Any who, I feel much better about this solution and hope that's the end of it.
Edit (clarification/correction): When I talked to my guy at the shop in person there was some confusion on the oil filter housing versus the engine block connector pipe (also replaced plastic for aluminum). It was the engine block connector pipe (also Bomunik) that had the uneven mounting surface and needed planed then permatex, not the oil filter housing. The housing was good to go and they used the included seals, which they said looked like great quality also. Sorry for the confusion.
