Hi,

2015 F55 S 42,000 miles. Changed the front rotors and pads. Pumped the brake pedal to firm up the brakes. Flushed the brake fluid out using the Motive power flush. Did it by the book. Brakes still feel mushy.
Flushed again for some reason there was air in the left rear. I thought maybe I had the bleeder loosened up to much. Looked like there was air being sucked up through it. Brakes still felt mushy. Flushed again and the left front had air in the line. Flushed again and no air, but the brakes aren't as firm as I would like them to be.

So is there something I am not doing wrong? I have the Schwaben scan tool and nothing popped up as a fault.

I also have a 2009 R55 S and did the same exact procedure and the brakes are excellent.

Thanks,

Frank

 

Ive helped bleed 2 different sets of brakes, all started using a similar tool like you had and both didn't work. The only way that worked was a tube and another person pumping the brakes.

 

A caution on having a person pumping the brakes while bleeding them. As you get into higher car mileage, the part of the master brake cylinder that doesn't get normal seal movement during normal brake use starts to corrode. This doesn't affect anything, until someone bleeding their brakes pushes the brake pedal to the floor, to get fluid and air bubbles out of the line. Pushing the seals over the corroded areas starts cracks in the seals, which will fail in the not distant future, which means a new brake master cylinder. First happened to me in a Volvo years ago. Porsche even cautioned about pumping the brakes in high mileage cars in one of their factory shop manuals.

If you want/need to pump the brakes while bleeding them, don't pump them to the floor. Go a little more than normal brake travel, and no more than half way. I've used the Motive brake bleeder successfully for years ... bleed the brakes with it, then give a couple of short presses on the brake pedal before tightening the bleed screw. I also tap the brake cylinder at the wheel with a wrench (or whatever is in reach) while fluid is flowing out, to ensure no air bubbles get trapped inside the cylinder.

 

Hi everyone, just wanted to share my experience from pressure bleeding my wife's 2015 Cooper's brakes for the first time this weekend. I'm a bit of a track junkie (though never with the Mini), and also a huge believer in preventative maintenance, so I've probably flushed brake fluid a couple hundred times in my 52 years (plus even rebuilt at least a couple sets of brake calipers with new seals). But with the F56 Mini brake bleeding, I experienced something I've never seen before.

I use a Motive pressure bleeder...probably used it with 15 cars over the past 20 years. A long time ago I got into the habit of simply using the Motive unit dry, that is, using it to pressurize the brake system without filling the Motive canister with new fluid to replace what is pumped out (I suspected it was introducing air bubbles in one of my track cars, which is something you don't want when hitting the brakes at over 110mph). So my normal process is to use a turkey baster to get as much old fluid out of the reservoir, then top off with fresh fluid, then use the Motive to pressurize the reservoir, then start the bleeding process at one corner taking the fluid down to the reservior's Minimum level, and then topping off the reservior and doing that process 2-4 times for the first corner (because you can't get out all the old fluid when you start), and then 1 or 2 times for the other corners.

This process works well, with the caveat that you NEVER let the brake fluid reservoir get below the Minimum line - the last thing you want is to introduce air into the system, and that becomes possible if the fluid drops below the minimum level.

My wife's 2015 Mini is approaching 50K miles, so I figured it was time for a brake fluid flush this weekend. The dealer did it at about 25K miles as part of their new car maintenance. She's got the non-S base Mini, but I imagine all the F56 Coopers use the same reservior.

The job started off normally. But when I got to the front passenger side, everything changed: air bubbles poured out of the line on that corner. After a couple drain-fill routines, I was still getting tons of bubbles, so I finished the other corner (totally normal...just like both on the driver's side) and returned to the problematic front passenger side. I always have a good supply of new brake fluid in the basement, and I went through 2.5 liters of fluid on that one corner trying to get it bubble-free. Now remember that I never come anywhere close to the Minimum line in this process. Eventually, I exhausted all my brake fluid reserves, so I closed the bleeder and I hoped for the best. I assumed the dealer had screwed up and let air into this corner when they did the flush at 25K miles.

When I pulled out of the garage, it was 10PM. I had spent 3 extra hours on that one corner! And now I had NO brakes at all. The pedal sunk to the floor! (I know not to push the pedal all the way down in situations like that, because it can damage the seals in the master cylinder.) So I used the handbrake to move the car to the driveway, and went inside to mull over how things had gone so wrong on a simple job. Google searching found nothing Mini-specific that would explain the situation. So I went to bed disheartened.

Got up the next day, and decided to give it another crack. Went and bought another 3 bottles of the correct DOT4 LV fluid (normally you should be able to do a full flush using a single bottle). While laying in bed the night before, I decided that *I* must be the problem, and was somehow introducing air into the lines. So this time I repeated the process, but didn't let the fluid level get down more than 1/3 from the Max line. And after about 5 flushes like that, the bleeder nipple was bubble free! So somewhere, in that reservoir, is a way for air to get in the system if you try to do a pressure bleed the front passenger corner with something less than about 2/3rds full. That didn't happen on the other 3 corners...I took the level in the reservoir down to about 1/3 above the minimum line and never had a single air bubble on the other corners.

So, bottom line: if you are doing pressure bleeding on the F56 Mini, be careful or you could inadvertently introduce air into the brake lines. I hope this helps someone else out there!

 

One alternative to avoid this situation is to put the brake fluid into the Motive bleeder. The downsides are that this creates additional cleanup of the Motive bleeder, may require a turkey blaster to remove some fluid if the brake reservoir is over-filled, and you could introduce air bubbles if you don’t carefully pour the brake fluid into the Motive container. It does avoid, however, the odd/exasperating situation slilley experienced. Thanks slilley for posting, good to know.

 

This could've helped me, lol.
I've been trying to bleed my brakes since Sunday (it's Friday now). Now, a gallon later, I think I've found my solution: gravity bleeding.
I used a Harbor Freight pneumatic vacuum bleeder and a MityVac.
The front passenger caliper: bubbles galore. The others, bubble free.
Pedal to the floor.
I tried Teflon tape on the bleeder threads as well as grease on the outside of the threads to no avail.
Note that the HF bleeder had a canister of brake fluid that is inverted into the brake reservoir cap, so it never ran low.
At some point, I ordered a Schwabben pressure bleeder from PelicanParts, and it's supposed to arrive tomorrow.
I thought I'd try gravity bleeding.
I just put a hose on the nipple and let it drip into a pan, not letting reservoir go low. Did all four just for laughs.
Rock hard high pedal with no assist.
I also did a round of elevating the hose to above reservoir height and let the fluid rise and tapped the caliper: did not see any bubbles emerging, and pedal was the same.
With vacuum assist it sinks some but stays at that level,naturally, but of course, I can't remember if it's the same as it was before. My thinking is, if it's high and rock hard without vacuum assist, and it was normal before I started to mess around, it's good to go.
I'm about to put the wheels back on and drive it.
Wish me luck because I live on the top of a hill, lol.

 

Came back from a jaunt down the hill. Works great.

 

Today I bled the brakes on my daughter's 2020 BMW X1 (F48 generation) with 30K miles. SAME EXACT SITUATION as I encountered in post #4 above with the right-front corner of my 2015 Mini. This time, I recognized the situation immediately as soon as the bubbles started pouring out (with the brake fluid well above the half-way point). So strange. So I went back to my notes, and did it again without letting the reservoir fall below 3/4. I don't know if it helped, but I also lowered the front-right corner so that the car was completely level.

 

I have heard of this issue if using the motive for pressure but not filling the motive with fluid. Also maybe you are opening the bleeders too much? I did my 2016 F55 with no issues. First I pressurized the motive at just over 15 psi for 5 minutes to make sure I had a good seal. I then filled it with brake fluid and repressurized to over 15 psi and checked that the pressure and brake fluid remained in the bleeder repressurizing as necessary. I then bled in the following order: right rear, left rear, right front and then left front. I opened the bleeder just a little and let it bleed slowly and repressurized as needed. No issues on mine.

 

Definitely not opening the bleeders too far. I'm curious @Smizrahi: when you did yours, did you put the car up on jackstands or a lift so that the car was completely level? I don't have a lift, so when it comes to doing brake work, I jack up one corner at a time which means that the wheel I'm bleeding is higher in the air than the rest of the car.

 

I had my car on quick jack 5000 lift so it was basically level.

 

I flushed my F56 brakes yesterday with the Motive Bleeder and got the same air bubble result. It has never happened before on any other car.

I think it is the brake reservoir design that has a baffle that makes it drain dry while still leaving brake fluid near the top.

As strange as it is, refilling the reservoir at 3/4 full will end the pain, (but what a pain).

Peter

 

Interesting the issues you guys are seeing using the Motive bleeder, never had an issue with my F54, which has been bled at least 6x since I purchased it. One thing I guess I do differently is that I vacuum bleed them from the caliper. I do suck out all the accessible fluid out of the reservoir, refill with new and then begin with the passenger rear, driver rear, passenger front and finally the driver's front. The container with my Mityvac Silverline kit is smaller than my reservoir, so I simply refill the reservoir after every container fill on the caliper end to prevent sucking in any air. When you do the vacuum method, it does help to teflon tape the bleeder screw threads, so you don't confuse air coming in around the threads vs through the system.

I have never liked pressure bleeding, just don't like the ability to push a ton of air into the lines if you miss something. Much harder to make a mistake with vacuum bleeding, IMHO. A neighbor spent 5+ hours tying to pressure bleed his Camaro's brake system and could not get air out of the ABS unit, so his system would not work at all...helped him push his car back into the garage, luckily nothing behind him when he tested it!! I vacuum bled the system and in less than 1 hour we had the air out and all was running again. He ended up throwing out his pressure bleeder and bought a vacuum bleeder similar to mine. YMMV.

 

Ha! In this case, the ability of the Motive pressure bleeder to bleed a lot of fluid is its downfall.

I think there is still an advantage with pressure bleeding (no air at the bleeder valve threads) and we just need to monitor the fluid level more carefully. I have never experienced this before and blame it on the reservoir baffle design.

 

I use a Schwaben pressure bleeder (similar design to the Motive) and have not had an issue. However, I am absolutely paranoid about the fluid level -- I don't give it even a hint of a chance to get low, I check it far more frequently than necessary, and I operate at just enough pressure to get things to move but not fly. Slow tortoise approach to finishing the race rather than being the hare. May not be necessary, but it hasn't failed me yet (or even come close to failing me, so far as I can tell).

 

I’m not sure about my situation as I had my son monitoring the fluid level and he struggled with the job. I used Valvoline synthetic DOT 3+4 brake fluid and it is exceedingly clear and hard to get a fluid level reading. At least for my son.