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Pinhole in the Hard Brake line

1759 Views 4 Replies 3 Participants Last post by  l1tech
Hi everyone,

Looking for a little insight here. I just got a new to me 2004 530i and I was driving yesterday and the pedal went to the floor and I got a low brake fluid warning.

I assumed that the previous owner just never kept up on it and the fluid got low and some air got into the system. I proceeded to just do a full brake fluid flush and topped everything off.

It was fine for about another hour's worth of driving, until I got the low fluid warning again. Now I remember that the rear's were difficult to bleed, and that got me to thinking that there must be a bad leak somewhere else. I pulled off the plastic underbelly pan, and low and behold there was about a 1/2 gallon of brake fluid sitting in there. I had my wife pump the brakes for me a few times and I found a pinhole leak in one of the coated steel hard lines that run from the firewall to the back under the driver's seat. There were two lines and the one that failed was the outer most line closest to the driver's door. There was areas of corrosion all over it actually.

So my question is, is this common? And do I need to order a new line form the dealer? Or is it better to just fabricate one? I saw that it connected to another line towards the rear, but I wasn't able to see up into the firewall where it connects to in the front. Is this a DIY project? Anyone have any experience with this?
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I do a lot of DIY work but I don't have the balls to build my own brake line. If it is a bolt in part yes but I wouldn't be rigging up some sort of repair.
I'm not sure about BMW but alot of manufacturers do not stock these lines, if they reguire replacement they are made to fit. You can go to parts stores and buy sections that are already flared and ready to bolt on but chances are that they won't have the exact length you need. Check with your local dealer though, you never know they may be able to order it.
OK, here's an update. l1tec, you were right, none of the dealers stocked this line, so I just bough some "european" bulk brake line from the auto parts store and a line bender and I copied the old one as best I could and installed it.

Worked like a charm and was much easier than expected. The hardest part was removing all the underbelly pans and plastic pieces coving the lines. Anyway, line is in, no leaks, everything is good. So, once the line is in I bleed all the brakes, and took it for a test drive. Well, the brake is still mushy. It works OK, but there is obviously air still in there somewhere.

Now since the brake line was off, and the master cylinder res was emptied when the line broke, I'm sure there was a lot of air in the system. In my Bentley Manual it says that you need to hook it up to a BMW computer and put it into bleed mode as "bleeding the brakes if there was significant air in the system will be very difficult to remove by traditional methods." Is this true? Will I be unable to bleed the brakes traditionally (with a MityVac or the old fashioned 'wife pumping the brakes for me' methods)?

Do I need to take it in to a dealer or Indy with a DISPlus, MoDiC or a GT1 computer to put it into "bleed mode"?
Your best bet is to have a helper push the brake pedal while you open the bleeder valve to bleed the brakes. Don't pump the pedal before opening the bleeder as all this really accomplishes is turning one air bubble into alot of air bubbles. In some cases where you have to cycle the abs valves in order to get rid of some of the air that is trapped in there and don't have a scan tool to do so I have had luck with finding a safe stretch of road and doing a few panic stops where you can get the abs to engage and then parking the car a bleeding the brakes again. Does the same thing as the scan tool does but just goeas about doing it differently.
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