My understanding is that you have air trapped in the ABS module and need to run the ABS bleeding function from the Foxwell service menu.

E53's also like to rust the brake lines that are directly under the driver seat. Check there for leaks in your system.

I also feel you on being frustrated. Go hammer some big nails into a stump or chop some wood. Maybe even go to a batting cage for a little session. Don't take it out on the old BMWs, they're way too fragile.

You may have to remove some of the undercarriage plastic to survey the entire brake lines.

@ual: photo giving me PTSD

So glad I live well outside the rust belt. The lines on Red looked perfect when I did the aero kit and had to remove all the cladding. I feel for you northern X owners.

Our X5 was bought in Canada so basically "if it can be rusted it is rusted."

So I just hopped on this thread to update that I have a leak in the lines under the driver seat, only to see the posts telling me to check the lines under the driver seat LOL.

What is the simplest way to repair this? Cut out a section and add in a section of line with a coupler? Or do I have to replace the entire section with probably-$$$ pre-bent line??

The FR had a ton of air in the system that came out when using the Foxwell. I got the brakes feeling 90% only to then realize I was dumping brake fluid on the ground and discovering the rotted brake line.

The car is up on a lift and it's putting a bit of pressure on the plastic panel making it hard to remove. That's a job for another day. Hopefully I can remove it without having to put the wheels back on and lowering the car down.

You need to fabricate lines with a double flare to replace the section that is rusted out. DON'T use any compression fittings for the repair. That is a NO NO.

The entire panel needs to come out including the side cladding to expose all the nuts and push pins.

There are two ways to approach this issue.
1. Replace all the lines end to end in the rear - ABS to calipers
2. Unbolt and cut out the section under the splash shield that you posted - but be aware in high rust areas, there maybe other areas causing issues in the future. Common problem that has been posted before.

What you need: Special tool to do the DIN Bubble flare ends on the lines get the good one or the cheap one your preference.
Bendable lines and compression fittings. I used this company for all of the above.
https://agscompany.com/

You will need metric Compression fittings for each rear line (10 &12 mm if my memory is correct). To connect to the existing lines you will need to add on the compression flare nut, make a DIN bubble flare on the existing steel line, and have a metric UNION to connect it. You will need to make up a repair line to connect to the junction connector at the drivers left foot area under the vehicle (Two sizes of nuts once again). I will find the link to the process and post it.

Here is the link to help you with tools, lines etc
https://xoutpost.com/bmw-sav-forums/...s-steel-4.html

ISO flare not double flare.

I did this repair on my X about 2 years ago. You can buy all three parts for about $50, the tools for about $40 and the pressure bleeder for about $50-60.

There are a pair of fittings right below the left hand driver seat and about 7-9' of line from there to the fittings at the rear left.

I posted my method to exactly copy three existing 11 or so bends in the current pipe. And also how to greatly improve the ISO (bubble) flare tool that is not completely finished from the factory.

If you are replacing the line from fitting to fitting, yes you will do a DIN ISO flare on the replacement line, but if you are splicing into an existing line, a double flare will be better because double flare fittings are more abundant in the USA since most American cars still use the double flare for brake lines.

+1 on the need to make a DIN flare not a SAE double flare. Different makes have different solutions to the same fluid connectors.