[dotmaster206]

I just flushed/bled my brakes today and decided to do the clutch while I'm at it. Regret that now...

For info, the car is a 2016 340i xDrive.

I used a pressure blender, not the Motive type that is pushing brake fluid through the tube, just an air pressure one. I did the brakes first, no problem, pedal feels super firm. Then I did the clutch. I took off the million screws to get the panels out of the way and got the slave cylinder bleed screw open (plastic ). I had filled the brake fluid reservoir to be full before attaching the air pressure fitting, same as I did for the brakes and then pumped up the pressure to about 10psi. Because of the tight space I just let the slave cylinder fittingi drain out into an oil pan. After maybe 30 seconds I closed the bleed screw assuming that was enough time to clear the whole line with new fluid, can't really tell without a clear tube to see it but good enough. The brake fluid reservoir was still well above the minimum level after doing this. I topped the reservoir up to full and called it a day.

But, just now I went to take a drive and my clutch pedal is on the floor, no pressure at all. What did I do wrong? Is there a trick? I tried pulling on the pedal and pumping it a bit but it's not building pressure. I have no idea what the reason for this is. Seems like it should be very straight forward. Any help? Thanks!

[schernov]

Bmw instructions says to attach "bleeder unit" and pressure not to exceed 2 bar

[dotmaster206]

2 bar is almost 30psi, so definitely didn't create problem there at 10psi I was using. What's the bleeder unit?

[schernov]

Probably a power bleeder which pushes the fluid thru.

[Cytoplasm0671]

Have almost your exact car (mine is 2017). I used 15psi and it works fine.

[Cytoplasm0671]

Oh I see where you went wrong. The reservoir for brake fluid actually has a partition in it that you can't see. So if you drain out all of the clutch fluid, which it sounds like you maybe did, then it'll still show as full in the reservoir. The reason BMW does this is if the clutch fluid has a leak then you still have usable brakes. Much safer. What you need to do is attach a power bleeder to the reservoir, crack the slave bleeder valve, and push fluid with the power bleeder until the fluid comes out clear and free of bubbles. Then tighten the slave bleeder valve without letting air get back up in there.

If your power bleeder overfilled the reservoir, use a turkey baster to suck out fluid from the reservoir until the level rests at max. Done!

[dotmaster206]

This was indeed the problem! Thanks so much for the idea, I am back in business

It ended up being way easier than re-bleeding, even. I think the air was only to the master cylinder and not in the line. I filled the reservoir up to the top of the strainer basket, within maybe 2mm of spilling over the top, and hooked up my power bleeder. I pressurized to 10psi and then just pumped the clutch pedal slowly. Immediately it started feeling better. I pumped it maybe 20 times and it was feeling the right resistance from the very top of the pedal. Took it on a test drive and it feels totally normal.

The fluid never got to below the max line. I sucked out the extra with a syringe and that's that.

After this experience, I might actually go ahead and do the CDV delete. I think I understand the bleeding difficulties now. It'll still be a pain with the xDrive components in the way but it seems doable.

Thanks again for your help!

[fleetfoot]

Originally Posted by dotmaster206

This was indeed the problem! Thanks so much for the idea, I am back in business

It ended up being way easier than re-bleeding, even. I think the air was only to the master cylinder and not in the line. I filled the reservoir up to the top of the strainer basket, within maybe 2mm of spilling over the top, and hooked up my power bleeder. I pressurized to 10psi and then just pumped the clutch pedal slowly. Immediately it started feeling better. I pumped it maybe 20 times and it was feeling the right resistance from the very top of the pedal. Took it on a test drive and it feels totally normal.

The fluid never got to below the max line. I sucked out the extra with a syringe and that's that.

After this experience, I might actually go ahead and do the CDV delete. I think I understand the bleeding difficulties now. It'll still be a pain with the xDrive components in the way but it seems doable.

Thanks again for your help!

Thanks for this post. It saved me a bunch of time. I did pretty much the same thing, but perhaps a bit more meticulous so I thought I would share my procedure:
1) Top off the brake fluid reservoir
2) Hook up the pressure bleeder (with fluid in it)
3) Start pressing the clutch pedal. Wait 5 seconds between each push to let the clutch partition refill. Press about 15x and watch the bubbles come up the pressure bleeder tube
4) Go under the car and open the slave bleeder valve for 5 seconds and watch the bubbles come out
5) Repeat steps 3 and 4 until the pedal feels firm again. I did about 4 cycles, and after that my pedal felt 100%. YMMV.

Today was my fifth time flushing BMW clutch fluid over the past few years using a Motive Pressure Bleeder. The past 4 times went beautifully, but today I somehow messed up and got air in the lines. A little ways into the flush I suddenly saw a BUNCH of air bubbles coming through my catchcan tube. I went up to the clutch pedal and as it sank to the floor, so did my stomach. I'm pretty sure it happened because I left the slave bleeder valve open too long, and the clutch fluid reservoir went dry, even though I had the pressure bleeder filled and pressurizing the brake/clutch fluid reservoir. So moral of the story is: when you're bleeding with a pressure bleeder, you should still probably only open the bleeder valve for max 10 seconds at a time; then pause to let the clutch partition refill and repeat as needed.

[B58 parts]

I've had this a few times. I think the trick is to only crack open the bleeder screw the tiniest bit so that fluid just starts to drip out. And wait for it. If you open the bleeder screw further it starts to suck in air. And if you open it further it will really suck in air and you'll have all kinds of noise and fluid rushing everywhere.

I had a hell of a time getting the E36 pedal solid. And the third time I just cracked it a tiny bit and it worked perfect. The first two times it was sucking up air.

I also use the pedal holder tool and push the pedal to the floor before pressurizing the reservoir. The motiv pressure bleeder is a great tool. My cap is getting a little used sometimes it doesn't seal the first try.

If you go under the car sideways with your legs out hanging under the passenger door it's easy to see everything. Tekton 11 mm stubby ratcheting box wrench if you have a front prop shaft there, it's really in the way.