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Discussion Starter · #1 ·
I woke up yesterday to some brake fluid under the car, then my pedal softened up a bit. The master brake cylinder is dry, but I definitely have a brake fluid lead from somewhere under the right side, just in from the right wheel (see pics). Here's the question. Does anyone have a diagram that shows where this rubber hose from brake cylinder reservoir goes to, as it believe it is the culprit here.

Much appreciated..
 

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The hose coming off the back of the reservoir goes to the clutch master cylinder in the driver's footwell. Could be one of the lines coming off the ABS/DSC unit, or the line going to the front right brake caliper, based on your second picture. Check the two hoses that come off the back of the ABS/DSC module and run right next to the engine. A lot of heat close to those hoses, they have been known to fail.

(#3 and 4 here)

 
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Your mid-brake lines (the ones the come into the back of the ABS have failed. Get stainless lines and call it a day. ECS sells some, I have them on both of my M5s
 

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Also, for future reference:

Sides are always from looking at the front of the car (or specified driver / passenger - and LHD/RHD in that case)

Your issue is the left / passenger side
 

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Discussion Starter · #5 ·
The hose coming off the back of the reservoir goes to the clutch master cylinder in the driver's footwell. Could be one of the lines coming off the ABS/DSC unit, or the line going to the front right brake caliper, based on your second picture. Check the two hoses that come off the back of the ABS/DSC module and run right next to the engine. A lot of heat close to those hoses, they have been known to fail.

(#3 and 4 here)

Thanks to both of you for the guidance I looked at the mid brake lines just now, they are dripping down to the plastic module below, and the drip seems to be hitting the exhaust headers, and then it's ending up underneath the car.

I'll try swapping these two out and bleeding out the system. Crossing my fingers, but I think this could be the issue...! One last question, these are these the mid brake lines you are referencing here...?
 

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Discussion Starter · #10 ·
Now a really stupid question. All of ECS tuning pictures of the product show them as a pair, on sale right now. Do you get two for one price, or do you have to order a quantity of two..? Yes, it's a dumb question.
Great news, thanks again all...
 

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Also, for future reference:

Sides are always from looking at the front of the car (or specified driver / passenger - and LHD/RHD in that case)

Your issue is the left / passenger side
Sides are with the reference point of sitting inside the car facing forwards. For a LHD car, the driver's side is the left and the passenger side is the right. His 2nd pic is the right front wheel well.
 
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Discussion Starter · #13 ·
Picked up the dealer provided mid-brake lines today instead of waiting two weeks from ECS. The replacement started fine, then while removing the lower line I snapped off the end of it. I believe I can cut the end off on the metal tube with the right tool, then re-flare the end (with the hardware on it) with another tool. I'll rent the tools I need this weekend, put it back together and then bleed the brakes- that's the plan at least.
 

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I wish I would have replied to this thread sooner.

I replaced those two hoses on my 2000 M5 earlier this year and rounded the nut on the hard brake line because it's such a tight area to work in. I found out it is a lot faster and easier to remove the hard line from the vehicle and then remove the rubber mid brake lines.

It's very hard to get a good bubble flare. BMW brake lines have bubble flares and not double flares.

I ended up replacing my hard line. Really cheap from BMW, but you have to bend it yourself to match the old one.

You're going to have to remove it to try to flare the end anyway so I would highly recommend just replacing it. I paid around $30 if I remember correctly for the new hard line from FCP Euro.
 
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Discussion Starter · #15 ·
I wish I would have replied to this thread sooner.

I replaced those two hoses on my 2000 M5 earlier this year and rounded the nut on the hard brake line because it's such a tight area to work in. I found out it is a lot faster and easier to remove the hard line from the vehicle and then remove the rubber mid brake lines.

It's very hard to get a good bubble flare. BMW brake lines have bubble flares and not double flares.

I ended up replacing my hard line. Really cheap from BMW, but you have to bend it yourself to match the old one.

You're going to have to remove it to try to flare the end anyway so I would highly recommend just replacing it. I paid around $30 if I remember correctly for the new hard line from FCP Euro.
Got it, I will check out the dealer today to see what they have. I need to get their diagram showing where this lower line connects to, this will make it easier. Thanks,
 

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[/QUOTE]
I found out it is a lot faster and easier to remove the hard line from the vehicle and then remove the rubber mid brake lines.
I agree with this. It's a tight work area and those connections have been cooking for years. I disconnected the upper ends of the flex hoses and removed the hardline through the fender well. You can then use a vise and proper tools to disconnect the hoses.
 

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Discussion Starter · #17 ·

I agree with this. It's a tight work area and those connections have been cooking for years. I disconnected the upper ends of the flex hoses and removed the hardline through the fender well. You can then use a vise and proper tools to disconnect the hoses.
[/QUOTE]

Hey thanks, one more question. Did you have to remove the front wheel to gt to the vendor well location in order to remove the metal line?
 

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Yes, I removed the wheel and the fender liner, and then detached the hardline from there. The connections in the wheel well are far more accessible than from above and were not seized. I don't imagine you'll be able to create a new bubble flare in the car anyway.
 

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Discussion Starter · #19 ·
The metal pipe that broke ultimately starts at the ABS module where it is stamped "HL" see picture. It then connects to the mid-brake line, then down in the fender well. Does anyone know where I can find the part number i need to get? I haven't found it yet on RealOEM.com. I have the outer mid brake installed already....!
 

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