Rusted brake lines, anyone?
 

I had the drivers side underbody cover off this weekend to change the fuel filter and noticed that the brake lines were rusted. I was pretty shocked considering that they are pretty well protected from moisture. Unless the covers underneath the vehicle are trapping moisture.

Has anyone had any experience with this? Wasn't there a recall of some sort regarding brake lines?

A poster here reported them; from fading memory, he had to pay to have them replaced and they weren't that "old"; again, from memory.
I can't find the thread via search and can't recall who posted it. Remarkable to me how that very important "line" would be so susceptible
to rust for a fairly new car. Penny pinchers at work, imo.
GL, mD

That's strange. I always thought brake lines were made of a non corrosive material. Never saw that before, not even on my high mileage vehicles. But they are not BMWs.

That's what I would think. But these have a lot of corrosion. You'd never know it either because the bottoms of these X5's are covered up. The driver's side cover has all those plastic push-in body plugs, so if you decide to take a look and get the cover off, be prepared with many new plugs; the old ones break.

Go with braided stainless steel brake lines (stoptech)...

I had mine replaced a couple of months ago BMW picked up the labor and the Dealer sold me the parts at cost.

These are the rigid brake lines that run the length of the car to the rear brakes. Not the flexible lines in the wheel areas.

#6 and #3 in this diagram:
RealOEM.com BMW E53 X5 4.4i Rear brake pipe DSC

I have not seen that kind of corrosion and any of my BMWs. I highly recommend a cleanup with a soft metal brush and then apply CorrosionX. I used this on all my cars and works fantastic. Just a light coat and wipe. My friend uses it on his plane (Piper Lance) and works great.

If I find any rust I treat it with Kurust and paint over .
use copper pipe if you replace pipes .

Never use copper pipe. There is a copper alloy available, which is safe. Safe in that it doesn't burst, but it isn't as strong as, and also does expand more, than traditional brake lines.

Brake lines have been corroding for ever, I think the issue here is just that most BMWs under discussion aren't old enough that it should be an issue yet.

Thanks for clarification JCL.
as far as I know the copper alloy is the only stuff available in brake pipe sizes but it is best to ensure using the correct pipe .

I hate to revive an old thread, but I just had this happen to my 2003 X5 4.4i. And mine look much worse than this! I lost my brakes on a road trip, so I got some extra pipe and a flare tool and spliced in a reapir piece, but I'd like to fix both of those lines the right way with all new pipe. I found the part numbers on Real OEM, and I'm about to order them, but I'm a bit scared to install them. I see that they both go over the back axel and then disappear from sight. Has anyone every replaced these lines before? Is there a DIY somewhere? I searched but couldn't find one.

On a side note, this exact same thing happened to my 2004 E60 less than a month ago. Very frustrating. I've had cars much older than these two and neither has given me grief like this. With something as important as brakes, you would think they'd have a more robust coating on them. I drive my kids around in these cars, and losing brake pressure is a dangerous occurrence.

Anyway, I'll stop ranting and if anyone has any personal experience or DIYs they could share on the replacement on this 04 X5, I'd greatly appreciate it. I'm really nervous that I'll have to drop the gas tank or major rear suspension parts to get to it.

Salt corrosion is the main reason I will never buy a vehicle that has been operated in the "rust belt". The road dept spreads salt and other crap on icy roads and when you drive over it your tires turn it into a saltwater (corrosive) mist that gets EVERYWHERE. The best bet to avoid this is to drive 2ndary roads that are not salted (used to do this when I lived in the northeast). Remove the covers every spring before a detailed chassis flush/wash followed with a light lube chassis spraydown after dry is a must for everyone in the yellow area of the map below.

My '03 X is in the 10th yr of service and other then a light coating of dust/dirt those lines look new, but my X has never seen snow/ice. :nanana:

I agree that it's the salt that's causing the issue here, and probably why both of my cars suffered from the same issue at nearly the same time.

I also just did some more research and it turns out that you apparently do have to basically drop the entire rear end of the car to get the new lines in. Hopefully someone here might have a way to get around that. Otherwise this looks like a HUGE repair.

But you would think BMW would know better, being an airline pilot and in the Air Force I've spent many a winter night in Germany, the winters are brutal there!

You splicing them should be fine as long as you used the proper lines. Leave it that way. Coat the lines with POR15 if you are in the rust belt. That is the sauce.

Brake fluid leak at an individual location will not render you brake less. You have a bunch of time till you lose enough fluid to empty out the reservoir. I know this because a drilled rotor blew up on me once destroying most everything attached to and including my wheel. No brakes. Bent the line, squished it, and drove home with it dripping. So keep it cool with those rusted lines, just don't leave them that way. Address the issue.

This is a very common problem in that exact location on E53s.

Solution is to splice in new brake line, no need to re-run the entire lines.

Does anyone know the splice tubing size to use for the X5?

4.75 mm pipe or nearest equivalent .

Just remember, that if you decide to repair the lines by splicing in a section to replace the damaged one, they are high pressure lines. Don't use standard compression fittings. You should only use flare type fittings, with double flares on all ends.

Based on the advice here, that's what I did. I cut out all the bad parts and spliced in new pipe. I got the factory bubble flared pipes and used that to join it in the front, and then did a traditional double flare on the two ends I connected towards the back.

I only hope that the sections of the pipe I didn't replace which were buried up in the back above the gas tank and rear suspension don't rupture. Those will be a real pain to get to.

So far so good though. No leaks. I just need to properly bleed the system. Th e pedal is still a little soft and I fear I may have to take it into a shop to have them put the ABS and DSC into "bleed mode" on their computer. I'm also getting a brake pressure sensor fault, but I hope that's related to the leak, as I just changed that a few months ago.

Wasn't there some theory that the A/C condenser ends up dumping water on the brake lines which causes them to rust prematurely?

The A/C drain dumps on the front driveshaft spline.

Mine just broke today while compressing the calipers to put the new brake pads on... mech said I gotta come back tomorrow because he has to get some tool to bleed/calibrate the system...

My wife was on a short road trip and the break fluid warning light came on. She picked up DOT 4 brake fluid and topped it up and got back on the road.

I took it to my mechanic as soon as I found out and sure enough, rusted break lines. :yikes:

I just found out last week that my brake lines in that exact spot was leaking fluid, now I`m trying to fix them, but the dam rain here is slowing me down.

On a preventive note...

I just drilled a hole, this way I can spray water using a garden hose to clean brake pipe every Spring (around April-May every year) w/o removing the fat-ass cover.

- Bought the 3/4-inch Jeep rubber plug used to cover Jeep differential. As it turns out, although this is called 3/4", one needs to use a 7/8-inch drill bit, which I didn't have.
So I returned the rubber plug ($3 at local auto parts store).

- Instead I simply drilled a 3/4-inch hole as shown and left it open.

Then hose it every April-May or so. Or hose it every 3 months or whenever you like...

not a bad idea.
on a side note, splicing brakes is a pain the the you know what. I think I got er done but I will leave the cover off for a week or so and keep an eye on things.

cn90, good call on drilling the hole, it actually may be better to leave that hole open since I think part of the problem is there isn't enough airflow with the "big ass cover" on there and the moist air/salt gets trapped.

If any of you guys are having to drop the cover to fix the brake lines, consider replacing the fuel filter as well just while its open.

Break fluid light had come on once, refilled and noticed a puddle under the drivers door. Mine are rusted in the exact spot. In the process of splicing new lines. Seems like a very odd location for a leak. They are well covered by the floor pans. The exposed lines look far better. Really surprised by this repair.

Just swapped the winter tires on today. The rear hard lines that run along the suspension arms on mine have lost the outer protective coating and are rusting. Cleaned them up and rust proofed. But the plastic guides seem designed to trap crud. I'll just have to clean them more often and keep an eye on them. Or wait for the puddle :)

For me, it was a lot of rotted leaves that did me in.

Just traded her in, though. May go for an e70 next year. ;)