E70 stainless brake line install warning

[HalP]

Hey everyone, I recently decided to install stainless steel brake lines on my 2011 Alpine White X5M. I had this done to my 2008 E70 X5 4.8i Sport back in 2010 by a local garage that is no longer in business, so I decided this time to do it myself. How hard could it be, right? I have done this on other vehicles I have owned over the years and it was always simple and straightforward.

For anyone considering doing this as a DIY, be VERY VERY CAREFUL not to let the the brake system completely bleed out during the swapping of the hoses! I accidentally made this mistake when I decided to paint my rear calipers during the swap. Even though I had the rear jacked up higher than usual, and raised the old hoses after removing the calipers, gravity wasn't my friend and when I returned to install the freshly painted calipers a few hours later, the overflow pan I had placed under the open hose was almost overflowing and my vehicle was brake fluid free!

I went ahead and swapped out the hoses and re-installed the rear calipers and attempted to bleed the system. That's when I ran into problems. I couldn't get all the air out of the system no matter how many times I bled the brakes (about a dozen attempts in all). Frustrated, I took it to my local BMW dealer and asked them to bleed them for me. IT TOOK THEM SIX HOURS to finally bleed the brakes and get all the air out! The tech was so frustrated he basically told me he was never going recommend swapping brake lines on an X to anyone from that point on! I'm pretty sure he was cussing me up and down by the end too (probably sooner than that)!

It ended up costing me over $600 in labor to get the brakes air free!

Just thought I would post this for anyone considering doing this. The stainless lines look great, perform great, and I'm glad they are now installed, but I don't think I would attempt this again. Something that used to be so simple, isn't simple any more! Which is true for just about anything on today's uber-sophisticated ultimate driving machines!

[larryv]

That is good to know. How does the brake pedal feel? Stainless lines a painted calipers i bet it looks nice.

[blue dragon]

This is not a stainless brake line issue. I'm running stainless braided lines with X5M caliperswith zero issues. The issue is that you failed to cap the open lines with the little rubber bung that comes with new lines, when you removed the caliper. Either way, glad you got it solved.

The dealer software will activate the ABS unit to remove bubbles that are stuck.

[HalP]

Originally Posted by blue dragon

This is not a stainless brake line issue. I'm running stainless braided lines with X5M caliperswith zero issues. The issue is that you failed to cap the open lines with the little rubber bung that comes with new lines, when you removed the caliper. Either way, glad you got it solved.

The dealer software will activate the ABS unit to remove bubbles that are stuck.

That is correct. Capping the lines will prevent this from happening. For some reason, the lines I bought didn't include any, but I probably could have mcgivered something.

The tech also told me he ran the ABS unit activation software six times before it finally cleared all the bubbles. Definitely adding to his frustration.

I have no issues with the brake lines at all, exactly as expected, firm pedal feel and look great.

[mitch808]

The trick/tools that a dealer has access to, to cycle the ABS system, is invaluable in cases like this. Otherwise, you'll end up doing what you ran into, with no promises to an end in sight.

Alternatively, you take it out for a drive, drive carefully, and find places to activate the ABS on your own (e.g. sandy/dirt area to do hard stops), then go home and bleed again, rinse repeat another time or two. (Ask me how I know this...)

[HalP]

Originally Posted by blue dragon

This is not a stainless brake line issue. I'm running stainless braided lines with X5M caliperswith zero issues. The issue is that you failed to cap the open lines with the little rubber bung that comes with new lines, when you removed the caliper. Either way, glad you got it solved.

The dealer software will activate the ABS unit to remove bubbles that are stuck.

BTW, I successfully upgraded the front brakes on my 2008 4.8i Sport to X5M rotors, calipers, shield and pads after reading your DIY. KUDO's and Thanks!

[JupiterBMW]

I ran into this same problem on my previous 3 series. Luckily, I now have all the software used to code and troubleshoot, so when I did brakes on my current car, I ran the ABS activation at each wheel. The pedal was ROCK HARD.

Honestly, if you're flushing the system, even just for maintenance, its a good idea to do this to ensure you get all of the old fluid/air out of the system.

[SilentAttack]

And I just took my calipars off to paint them. I planned on doing a full flush. Hopefully I don't run into issues

[msan]

When doing anything requiring brake line disconnection you should use a stick and push the brake pedal down and use the driver seat and the stick to keep the pedal pressed down, you will lose little fluid if you do this. You can cap them for added insurance

[heatmizr]

^ That sounds like an easy way to accidentally push the piston too far in your master cylinder and damage the seals on it. Be very careful... At least that can happen on a motorcycle master cylinder.
No need to do both, just cap the lines.

[msan]

Originally Posted by heatmizr

^ That sounds like an easy way to accidentally push the piston too far in your master cylinder and damage the seals on it. Be very careful... At least that can happen on a motorcycle master cylinder.
No need to do both, just cap the lines.

It's straight from BMW TIS

[deansbimmer]

Originally Posted by heatmizr

^ That sounds like an easy way to accidentally push the piston too far in your master cylinder and damage the seals on it.

That's not a thing. Holding the pedal down is common practice by those "in the know". It blocks flow from the reservoir, essentially shutting off the fluid flow.

[heatmizr]

Huh, how about that... I have never seen the inside of the master cyl piston on an X5.
I know it can be an issue on bike brakes. Especially on older models where there could be corrosion inside the cylinder where the piston doesn't normally travel, and tear the rubber seals on the piston. Resulting in the need for a master cyl rebuild.