Xoutpost.com - Brake Bleeding Problem

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It would appear my problem is not to do with bleeding at all but rather a leak from the rear port on the master cylinder.

Does this look like it's "in" all the way to you guys? I am reluctant to keep tightening it. I don't have a torque wrench that can go on a fitting like this.

BMW TIS says this fitting "Brake lines to hydraulic control unit" should be 17 nM
https://www.newtis.info/tisv2/a/en/e...-lines/5eAqjtl

I don't really think I can tighten this thing anymore...

Hard to say if the connection is tight or not. Meeting torque specs is the determination though if it is cross treaded torque specs will not be accurate. Did you remove this line or were the symptoms prior to the brake work similar to what you have now? Be sure to use a brake/fuel line wrench.

I don’t believe it’s cross threaded. I used my fingers to do it until it was almost all the way in then used my 12mm open-ended spanner. I did remove this line, it’s not possible to extract the brake booster (which was the point of the exercise originally) with this line (and the master cylinder) in place.

I bleed another container of fluid through it this weekend. Took it to a local parking lot. Pedal still like a marshmallow, but if you pressed deep down, it would stop the car..

Did a bunch of panic stopps, getting the ABS pump going. But it just seemed like the rear brakes were not engaging at all..

Quote:

Originally Posted by RajB (Post 1137662)

The ABS needs recycling to open the valve using the proper software as the rears have most likely bled out. That's the issue I had many years ago when I fitted my BBK.

Well, broke down and took it to the dealer this morning. Explained that I though there was air trapped in the ABS Pump and needed them to have the computer run the bleed sequence to get it out..

Hour and half later they brought it around. $143 dollars sir..

Drove it, somewhat, but not alot better than it was..
Went back in, asked if they test drove it..
Service advisor drove it, said felt fine to him..
Asked if they had cycled the ABS pump, he had no idea of course..
Took it to the shop foreman..

Another hour and half later, Advisor tells me they ran the 'bleed program' from the computer and asks me to test drive it..

Light years better. I'm still a little unhappy with the pedal feel overall, but at least all the brakes are working, and it is safe to drive again.

Hoping my experience is like "Ashaman", in that I've got a solid pedal engine off, but soft engine on

Quote:

Originally Posted by Ashaman074 (Post 988854)

I missed my next update, so I'll give a combined Day 4/5 :)

Day 4 I was able to properly pressurize the reservoir. I performed a full bleed, at each point I pressurized the reservoir, opened the bleeder. Allows the attached hose to fully fill, submerged in a container of brake fluid. Pumped the brakes 5 times. Ran the DIS bleed procedure. Pumped the brake 5 times. Started the engine, pumped the brake 5 times. Ran the DIS bleed procedure. Closed the bleeder. Sounds ridiculous; but I got a TON of air out of the system, mainly at the passenger rear.

So, after this raindance, I had a fairly firm pedal with the engine off, but it was still soft with the engine running. Hoping my pedal firms up too over the next few days, but not holding out a lot of hope.

The next day after work, I basically repeated the exact same process. Afterwards, I had a pedal that was rock solid with engine off, and usable with the engine running. I still didn't think it was quite as good as before, but at least I could drive it and bed the pads in.

Today I drove it to work, and they feel great. Not sure why it is any different than last night, maybe the fluid was a bit aerated; but they are fantastic now.

I sometimes like to check it after driving a few days to ensure no additional air worked its way back out of the system, so I'll probably do that this time too - but for the time being I am just happy to lay it to rest - What a fiasco!

You can be darned sure I'll watch fluid levels like a hawk the next service; that is for sure!

But yeah, pressure bleeding running the "Bleed Procedure" routine were key. It was difficult enough and took enough time even with them, I don't think it ever would have been possible without them. I suppose this is pretty typical of any modern AWD vehicle, but it was a frustrating bit O' learning for sure. Thanks again to everyone who helped!

Thanks everyone for your feedback..

P.S. - Would be nice if you didn't have to tell the dealership that there is a procedure to run on the computer to get the air out of the ABS pump..

Quote:

Originally Posted by FourPointEight-is (Post 1137770)

From the picture that you posted it looks as though it is cross-threaded. I changed the spark plug on my second Lotus and I threaded it in by hand, but when I tried to tighten up the plug with a wrench I felt that something was not right. Yup, you guess it I cross threaded the spark plug hole. Lucky for me I had a spare head that I install to fix the problem that I created.

ABS BLEEDING ISSUE

It appears in my research that the ABS can have air bubbles which are difficult to evacuate, been through three bleeding procedures and cannot get full braking, worse yet, brakes lock up when hot at precisely same point in daily drive. Pressure bleed, but very little air came out at calipers. Unlocked the proportion valve which was preventing rear brake bleed as the brake line ruptured and had them replaced. So this is where my problem started, got stuck taking it to a independent who supposedly knew BMW's, yes he came back and said I need master cylinder when he could not bleed rears, and he had no diagnostic system evidently. So got screwed, took it home on front brakes only, replaced master cylinder and no difference, which led me to researching issue myself, bought the bleeder diagnostics, got to bleed rears, but using vacuum bleeder was not working, bought pressure bleeder, got more air out, but still same issue of soft peddle and only 50% braking and still locking up. I read that jacking up rear is solution for stuck air bubbles in master cylinder, so I am stumped, will try to bleed again. Any suggestions?

Thanks,

There's a specific order on bleeding and you must activate the ABS while doing it or else you basically are just pushing bubbles back and forth in the block.

Believe it's RR, LR, RF, LF but I don't have it in front of me to verify. Sorry

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Quote:

Originally Posted by EODguy (Post 1188300)

I learned this the hard way after replacing a rusted out line to the back. It never dawned on me, as I read through all the threads and reviewed ISTA/D on procedures until I broke down and took it to the dealer. It may be self evident but I didn't think of it in trying to do this single handed. I asked the dealer and they have 2 people bleeding the brakes. IIRC, one pumping the brakes while the ABS is engaged via ISTA and one cracking the bleeder screw open.

I bought a pressure bleeder thinking that I would be able to do this by myself AND while activating ABS. No such luck. I had the steps right, starting at the right rear wheel, but it is a 2 man job.

If there's any DIY I just can't stand doing it's brake bleeding - so f#$@g bloody tedious but must be done right, or else .... So, for $120 done at my local dealership, I call it money-well-spent for such an onerous task.