Tell us year/model of your car. Better yet, put that info into your profile.

 

It’s a 2003 330ci MT. I’ll put it in the bio now.

 

That line should be for your right wheel.
It is just a interconnecting, you can buy OEM or aftermarket.

 

This is using my 02/2003 330Ci vin on realOEM

Use your vin to verify, there were changes in 03/2003 for some parts (not brake parts specifically)

Your picture looks like it has part number 3 in the picture below.

RealOEM.com - Online BMW Parts Catalog

 

As said above its the pipe to the opposing wheel its possible to change it by lowering the fuel tank a little ie remove the straps and support the tank and use the access panels under the seat.

 

See that’s what I thought but I called a BMW parts department and he said they are all individual lines and don’t interconnect…that’s why I was so confused…

so for my clarity, based on the photos and information I’ve provided you are u see the impression that connector is part 3 and the bending line in the photos is part 4?

 

Yes buy and fix.
You can replaced that without dropping tank.
Because it is above subframe.
Just loose from from right wheel flexible connector and holders for better slack.

 

Thank you!!

 

I’ve been trying to find what part this is and what system it is a part of for a few days now.

It's a brake line, part of the brake system.

That will be $50.

 

So I believe that's a (coated) steel brake line... The BMW replacement will also be a steel line, which is a fine way to go.

You have an option - you can replace the rotted sections with Nickel Copper (Ni-Copp) lines, which are typically cheaper and easier to bend...You can likely even leave the the rotted lines in place and route the Ni-Copp line around it.

No problem connecting Ni-Copp lines with old steel lines, just use new fittings and junctions.

I have replaced most of the original brake lines on my E53 with Ni-Copp lines.

 

What do the other pipes look like?

 

That's gonna need parts 2, 3 and 4 as the long pipe to the ABS module is also quite badly corroded. You may be able to get away with cutting the rotten steel pipe back to good steel and reflaring it but that would then require a custom length of pipe from the joiner/coupler to rear wheel.

 

Ni-Copper / cuprinol - that is the DIY answer. If you look on realoem, and there is a number after the brake line like 950, or 1440 - that is the length in mm. If it says 10/10 , it is a 10 mm fitting on each end. If it says 10/12, one end has a 12mm fitting. This is rear? Left or right?

 

Yes. IIRC, I think BMW may have installed a 10mm fitting on one line and a 12mm on another to help prevent techs (or DIY owners) from mixing up left /right brake lines.

In my brake line kit, I have a spool of Ni-Copp line, both 10 and 12mm fittings and junctions, flaring and bending tools, etc.

 

I would look into changing all the brake lines on the car if any of them look like that, you're gonna get other ones failing real soon as well I'd guess

 

Might as well do the rubber lines too.

 

One other comment - BMW sells you lines - not pre bent lines. What you see in realoem is not what you get. Bending steel OE lines is a pain. the copper stuff is formable by hand, and will never rust. I've done this with copper.

 

My car is dumping brake fluid out of a copper line that runs from the back left corner to the back right

Copper isn’t rusted.

The chassis looks clean so why the pipe? You live in salted roads zone?

can you visit a junk yard and get the parts you need?
Coat the pipes with heavy grease

 

I would order the complete set of rear brake lines. They are not Copper as Copper would be too soft for the pressures. They are coated steel. NiCop is an option as it is within spec for the pressures and easier to route and bend. I would not consider DIY steel lines as they are difficult to bend and flare especially not having experience doing that. Flaring any lines takes practice and a quality flaring set you may never use again.

 

Just if people aren't aware. Pure copper shouldn't be used on vehicles as the vehicle vibrations work harden the copper and cause it to crack but it is rated for the line pressures used in brake systems. The Nickel/Copper alloy can be used on vehicles as the addition of the nickel removes the work hardening issue.

Steel brake lines are crap and used due to cheapness to manufacture. They can just as easily rust from the inside out due to brake fluid being hydroscopic and absorbing water over time.

 

First, a comment: great photos. They make it really easy to zero in on the correct lines.
I'll just add a couple practical suggestions based on my experience. Early and often spray all tubing connections with PB Blaster, or your penetrant of choice. Even if you plan to throw away old parts, the job goes easier if parts unthread more easily and you're not inflicting damage/destruction while working. Also, I really recommend using/getting flare wrenches to avoid, if possible, rounding off the flare nuts. If you need to resort to a vise-grip, working space gets much tighter. Harbor Freight (source for adequate, seldom-used tools) has flare wrench sets for $17 and $40; different size ranges so check before purchase.

 

And get a flaring tool that does DIN flares - get a length of tubing and practice - do it sitting or standing as a normal person, get good at it. then lay under your couch with a flashlight in your teeth. cause that is how it will feel under the car : ).

 

Also search for posts by @MrMCar and brake lines.