OK, folks, this one has me completely baffled. I just replaced the brake master cylinder and brake fluid reservoir -- filled it with fluid right to the top in anticipation of bleeding the clutch slave. I disconnected the slave cylinder from the trans and compressed it according to ModMini's video instruction. I then hooked up a Motive pressure bleeder to the master cylinder and pumped it up to 15 pounds as instructed. I attempted to bleed the clutch slave cylinder and did not get any fluid draining. I even disconnected the hard line going to the slave cylinder and still no fluid, even under pressure. I loosened one of the hard lines at the brake master cylinder and fluid is coming out at the connection. Clutch pedal is completely on the floor. And, yes, I removed all the plastic nipples that were inserted into all the orifices on the new brake cylinder but there's obviously a blockage somewhere. How is it possible than even under pressure that no fluid is exiting the clutch slave line? The fluid is not leaking anywhere else either. Minis are so fun!!! What am I missing?

 

Does not sound fun, apparently famous for retaining air. Read a couple posts in here and see if that helps

https://www.northamericanmotoring.co...ing-issue.html

 

Thanks for the link. I've watched every video I could find on the Internet. I'm trying the board pressing the clutch pedal thing tonight. My biggest confusion is not being able to get fluid out of the disconnected slave cylinder line. I'm afraid it may have something to do with the ABS module. I had no problem bleeding the brakes that uses the same master cylinder/reservoir as the clutch. I'm going to blame it on those way-too-clever-for-their-own-good BMW German engineers. I'm beginning to think it's retribution for losing WWII.

 

You hooked up the MOTIVE to the reservoir, not the master cylinder, right? If you're not getting fluid flowing down the line, there's an airlock or obstruction in the line. If the overnight pedal-down doesn't help, try a reverse fill by using a syringe or similar pump arrangement in order to "prime" the line, then close the slave nipple. Try bleeding again. Remember to loosen the reservoir cap while doing the "reverse fill".

 

As far as I'm aware there's only one way to hook up the Motive and that's at the reservoir, so yes that's what I did. I don't quite understand the overnight pedal-down process (even though that's what I did last night) because the pedal will go straight to the floor then stay there on its own. So, the pedal down process didn't accomplish a thing for me. About every other time I attempt to bleed the slave cylinder I get a small puff of air then no fluid. Once or twice there was continuous fluid flow but then the pedal continues to stay down with absolutely no resistance. Clarify for me: Are you saying inject fluid into the line going to the clutch slave? Or, remove the slave nipple and inject there? This is frustrating as hell because I've worked on cars for 60 years and never had this kind of difficulty bleeding anything. Any other thoughts?

 

Agreed, I've never heard of this happening either. Just crack the slave nipple and, with a large syringe attached to it with a short piece of tubing, inject brake fluid through and up the hard line to the reservoir. That should force the air out of the line and into the reservoir. That's why I mentioned to be sure that you don't have the reservoir cap on tight. If you meet resistance, there's an obstruction in the line or in the slave cylinder. Once filled, close the slave nipple. It "should" bleed properly now.

 

I have a pneumatic vacuum bleeder (Harbor Freight/Pittsburgh) that utilizes my compressor (https://www.harborfreight.com/brake-...der-92924.html). It works amazingly well on brakes (I highly recommend this product). Instructions indicate setting the compressor from 90psi up to 120psi and the kit works via suction. There is the ability on the pistol grip to regulate suction strength. It works by pulling fluid from the reservoir through the line to the nipple. The Motive uses 15psi to push fluid from the reservoir end and I have used it in the past to bleed the brakes but the Harbor Freight product does it much quicker and more thoroughly. Nothing has worked for me so far in my multiple attempts to bleed the clutch slave that uses the same reservoir and master cylinder as the brakes. What might the negative be in using this Pittsburgh product to draw fluid from the reservoir to the bleed nipple on the slave cylinder? Seal damage, other? Any thoughts?

 

I'm an old Navy vet and we have an expression that fits here: "Any port in a storm". In other words, what have you got to lose?

 

Navy vet here also. I'll let you know how it turns out. It may just be the answer to everyone's clutch bleeding prayer.

 

Given how involved you are already I'm excited for a result. To be an airlock at this point seems excessive, leaning towards a blockage.

 

I'm right there with you but I also can't envision a blockage since I replaced both the master cylinder and the ridiculously priced plastic reservoir and the brakes are bleeding just fine (same master serves both brakes and clutch). Update to come.

 

Attempted the suction method on the slave cylinder to draw fluid from reservoir and nada, nothing -- no fluid whatsoever came through. I even disconnected the main line to the slave and used suction at that point and still can't get fluid to flow. I disassembled everything again to ensure I didn't miss something being blocked and everything was as it should be. In my entire life I've never not been able to fix something but this one has me tearing my hair out and I don't have enough of that to continue.

I've seen one or two posts about possibly having to cycle the DSC module so I'm reaching out to the forum to see if anyone else had to do that in order to bleed the slave?

Afterthought: Should the engine be running when trying to bleed the slave? That makes no sense to me but I'm out of ideas!!! Anyone???

AfterAfterthought: Should the clutch pedal be up or down when bleeding? Tried it both ways and doesn't make a difference. Clutch pedal goes to the floor easily (no resistance) and stays there.

 

I haven't looked at mine to see what the layout is, but could your clutch linkage be broken so the pedal has no effect in actuating the slave?

 

Well, there's two hydraulic cylinders associated with the clutch. 1) clutch master cylinder that resides behind the clutch pedal; and 2) clutch slave cylinder that attaches to the front of the trans (on an S). There's a third - the primary brake master cylinder that provides fluid to both the brakes and the clutch cylinders. Everything was working with the exception that getting it into first was minimally more difficult which started this whole debacle of attempting to bleed the clutch. I replaced both the primary master cylinder ($108) that attaches to the brake booster and the plastic reservoir ($118) that holds the fluid. I've gone thru all the correct steps to compress the slave cylinder and attach a Motive pressure bleeder to the reservoir (at 14 lbs.), then bleed the screw attached to the slave (as you would do for your brakes when bleeding). I get a minimal amount of fluid then I hear a miniscule amount of air released but it's doing nothing to solve the problem. The next time I try to bleed I get neither fluid nor air. The clutch pedal is against the floor and will not activate no matter how many times I bleed the slave. My biggest conundrum is that even with the feed line disconnected from the slave I cannot get fluid to flow from it, whether under pressure or suction. That indicates to me that there is some type of blockage preventing fluid flow. I disassembled everything today and found no issues with any of the components. At the moment, I'm completely baffled. I just bought a couple of plastic syringes (thanks NC TRACKRATE) that I will use tomorrow to shoot fluid up into the feed line (after I reinstall everything) and hopefully flush what I assume is air (airlock?) in the line up into the reservoir.

 

I can't believe were still here lol. Could it be a faulty master?

 

That's my next investigation and I'll replace it if I have to. It's going to cost $125 to tow it to a shop, then the cost of repair at $185/hour, plus parts. That's anathema to me. I'll attempt to inject fluid into the clutch master cylinder behind the pedal via the bleed nipple (using an oil can filled with brake fluid and a clear plastic hose) because it is the direct line to the clutch slave cylinder. I'm thinking that if I inject enough fluid and eliminate most of the air in the line to the slave that I will be able to bleed the slave normally. It's become a f'ing contest now between me and this %$*()#$@ Mini. I refuse to lose. Update later.

 

Update: I've now replaced the brake master cylinder, fluid reservoir and clutch slave cylinder. The brake master cylinder and reservoir were both leaking so they did need to be replaced. I removed the clutch master cylinder yesterday (what a PITA!) and ordered a new one. When it was removed I manually operated it and couldn't feel any air pushed out the line openings so I'm hopeful that that part may be the culprit. Seems I may have replaced the slave (bleed still not working after replacement) for no reason but it's cheap and I'm restoring the car anyway. If replacing the clutch master cylinder doesn't work, I'm afraid I'm out of ideas. Positive thoughts only, please. More later.

 

I think that pressurizing system with the pressure bleeder should have forced your clutch pedal up into position. Since your clutch pedal remained collapsed while your bleeder was pumped up to 15psi, that could indicate that the clutch master cylinder has failed. I recently replaced my brake master, clutch master and clutch slave and used the same method you’re using. In my case, I suspect that the added psi from the pressure bleeder is what caused my clutch and brake master cylinders to fail after replacing the clutch slave cylinder.

I hope replacing that clutch master does the trick for you.

 

I’m curious how the pressure bleeder could cause failure of a component other than the reservoir given that 15 psi is far below typical operating pressure.

 

Good question but I will say that my brake master cylinder was not leaking until I pressurized the system. It then started leaking at the mounting point with the booster which indicated bad seals. The pressure also must have contributed to a hole in my reservoir (on the back corner, not visible side) that wasn't leaking under normal operation either. I have no idea whether those parts were ever replaced so age/wear was mostly likely an issue. Given those leaks I wouldn't be surprised if the seals on the clutch master cylinder were also compromised. Only problem that I can see with that theory is that the clutch master cylinder was not leaking fluid anywhere. Waiting for the clutch master cylinder to arrive that I bought at FCPEuro. $6.99 for shipping for up to 11 day delivery. 2-Day delivery for a $50 part was $145, believe it or not so the MC40 is up on jackstands in the garage patiently waiting.

 

I can only attest to my experience and as soon as I pressurized the system fluid gushed out of the seal of the mounting point on the brake master cylinder. It was an immediate and obvious failure.

 

Ah. I think I was just being dense, and that makes sense to me. IIRC, the seal at the very back never really sees any pressure.

 

Final update: It was the clutch master cylinder that was preventing proper bleeding. I replaced it and all is good now. I've worked on cars for 60 years and I rebuilt almost this entire car and never have I run into something as difficult to replace as the $%^@#! clutch master cylinder. There is absolutely no room to move where it's located. Why BMW didn't provide a separate master cylinder reservoir for the clutch I'll never understand. If you do decide to replace yours, do yourself a favor and remove the driver's seat first. This thing is impossible to access otherwise. Final word of caution: Unless you're under 4'6" and have small hands or your 8-year-old is a great mechanic, let someone else replace it.

 

Dang, what a battle but I'm glad you sorted it out. I often wondered how fun that would be to replace on the mini! Mazda is known for this ridiculous location aswell, battled a buddy's Mazda 3 before and did not enjoy ourselves one bit. I feel your pain!

happy motoring!

 

Well, today I drove to the golf course really enjoying the drive after a month in the garage. On the way home I heard a tiny whine then the clutch went straight to the floor and stayed there. Haven't look at it yet but I believe it leaked fluid at the slave cylinder where the hydraulic line connects. Had it towed home (8 minute tow cost me $140) and I noticed a few drops of fluid on the garage floor. Drove fine yesterday and part of today. I begrudgingly accept responsibility because I'm the one who hooked up that line. Oh, the joys of MINI ownership!!!