Brake Leak But Can’t Find It! Help!!

[drewusmaximus]

Hi all, 2002 A4 Quattro 1.8l turbo

This car is my stepsons. I believe there’s a leak at the passenger front but I cannot find the leak. The red Brake light indicator keeps blinking on the dash with no beeps. The reservoir empties after driving. He keeps filling it up. I have pulled the front passenger wheel to look for the leak but, it’s dry. All other wheel appear to be dry, however I can see that it’s wet between the passenger front door and the front wheel well on the inside of the body. I suspect it’s the hard metal brake line but, I cannot trace it. It’s as if the line goes into the body of the car and it’s looks as if it cannot be accessed. I’m hoping to cut and repair the line but, I can’t find it and I don’t know how to access that area. I’ve pulled the wheel off and had the car on ramps and it’s too difficult too see way in there. We are at a point where my stepson is putting fluid in the reservoir every time he stops at his destination.
I would like to fix this before it gets too cold here in update NY. I would greatly appreciate if someone can tell me what to do or have a diagram of the brake lines so I can trace the lines.
Thanks in advance.

[drewusmaximus]

Anyone have any advice? I can’t find any instruction on how I would be able to access that brake line.

[jpulll]

Might have to remove the fender liner to access it. The abs module is right by the coolant and windshield washer reservoirs. Follow the lines the best you can till you find your leak. Have him turn the car on and give the lines pressure so you can find the drip. That much fluid will definitely end up on the ground somewhere, wouldn’t be hidden in the chassis.

After you find your leak and repair it, make sure to flush the system and use pentosin or oem fluid.

Sent from my iPhone

[rovert6]

If I were you, I'd have the front up on jackstands and have your step son press and hold the brakes with the vehicle off. Have both front wheels removed and look around the caliper, and the brake line itself where it connects to the hard brake line. See if you can spot any leaks coming from these lines while he is pressing on the brakes. If he can feel the brake pedal move while the vehicle is off, then it is leaking somewhere. Inspect all 4 brake lines, and if there is still no visible brake fluid leaking, look at the ABS module in the engine bay as well.

Report back with what you find

[Kevin C]

A leaky rear seal in the master cylinder will cause fluid to disappear. Also, since it's a safety issue I would consider bringing it into a shop if you can't find the issue. Driving it broken is not a good option.

[Biged243]

Like said jack the front up fill and test. Remove lining and trace from caliper to booster. Make sure there are no cracks or holes in the rubber line from the caliper to hard line.

[rovert6]

Any luck on finding the leak?

[drewusmaximus]

Any luck on finding the leak?

No I haven't yet. I have found the fluid on the frame of the car by the front passenger wheel. The line to the caliper is fine on all four wheels. No leaks at any of the wheels by the caliper. The fluid is dripping from the frame of the car. My assumption is, the hard line from the ABS to the front right wheel is most likely leaking but, I think the part of the line that runs against the unibody of the car is where it's leaking.
I didn't have to remove the lining. I followed the rubber line that connects to the hard line. Then the hard line loops up and over the front frame of the car, then loops back down and bends towarfd the front of the car and I assume bends toward the driver side to the ABS module. But, when my fingers reach over the front frame I can feel the line but, my hand can only go so much into the hole and consequently, can't follow the line. Oddly, i can see where the lower control arm is bolted on, is where the fluid is landing. I wiped that connection not too long ago and it's saturated with brake fluid. So, I assume the leak is occurring where the brake line meets witht he front frame on the inside but, I have no idea how to access that line. I looked form the engine bay and that whole section is covered. There is no room to reach my hand in to feel for leakage.
That's why I am hoping someone has a diagram so I can have an idea of where that brake line runs. I'm willing to replace that entire line but, if I don't know how it runs in the car, I won't be able to line it up.

[drewusmaximus]

No I haven't yet. I have found the fluid on the frame of the car by the front passenger wheel. The line to the caliper is fine on all four wheels. No leaks at any of the wheels by the caliper. The fluid is dripping from the frame of the car. My assumption is, the hard line from the ABS to the front right wheel is most likely leaking but, I think the part of the line that runs against the unibody of the car is where it's leaking.
I didn't have to remove the lining. I followed the rubber line that connects to the hard line. Then the hard line loops up and over the front frame of the car, then loops back down and bends towarfd the front of the car and I assume bends toward the driver side to the ABS module. But, when my fingers reach over the front frame I can feel the line but, my hand can only go so much into the hole and consequently, can't follow the line. Oddly, i can see where the lower control arm is bolted on, is where the fluid is landing. I wiped that connection not too long ago and it's saturated with brake fluid. So, I assume the leak is occurring where the brake line meets witht he front frame on the inside but, I have no idea how to access that line. I looked form the engine bay and that whole section is covered. There is no room to reach my hand in to feel for leakage.
That's why I am hoping someone has a diagram so I can have an idea of where that brake line runs. I'm willing to replace that entire line but, if I don't know how it runs in the car, I won't be able to line it up.

I think number 12 is what I am talking about but, not sure if that particular part is leaking or another line connected to that part that I can't seem to find that might be leaking.

https://parts.audiusa.com/a/Audi_200...N/1397315.html

[rovert6]

No I haven't yet. I have found the fluid on the frame of the car by the front passenger wheel. The line to the caliper is fine on all four wheels. No leaks at any of the wheels by the caliper. The fluid is dripping from the frame of the car. My assumption is, the hard line from the ABS to the front right wheel is most likely leaking but, I think the part of the line that runs against the unibody of the car is where it's leaking.
I didn't have to remove the lining. I followed the rubber line that connects to the hard line. Then the hard line loops up and over the front frame of the car, then loops back down and bends towarfd the front of the car and I assume bends toward the driver side to the ABS module. But, when my fingers reach over the front frame I can feel the line but, my hand can only go so much into the hole and consequently, can't follow the line. Oddly, i can see where the lower control arm is bolted on, is where the fluid is landing. I wiped that connection not too long ago and it's saturated with brake fluid. So, I assume the leak is occurring where the brake line meets witht he front frame on the inside but, I have no idea how to access that line. I looked form the engine bay and that whole section is covered. There is no room to reach my hand in to feel for leakage.
That's why I am hoping someone has a diagram so I can have an idea of where that brake line runs. I'm willing to replace that entire line but, if I don't know how it runs in the car, I won't be able to line it up.

Someone can correct me if I'm wrong, but I believe that hard line that you see on the frame rail goes into where the steering rack is, and then goes into the battery tray to the master cylinder. 12 on the diagram that you're talking about is on the caliper itself. #12 goes from the caliper to the rubber brake line. That rubber brake line then goes to the hard brake line that goes all the way to the master cylinder.

As long as there are no kinks/cracks in the main brake line, it may need a new fitting on the end. By cutting off the flared end and putting a new flare nut on, and re-flaring the end.

Is it possible for you to take a picture of where you wiped it clean?

[drewusmaximus]

Someone can correct me if I'm wrong, but I believe that hard line that you see on the frame rail goes into where the steering rack is, and then goes into the battery tray to the master cylinder. 12 on the diagram that you're talking about is on the caliper itself. #12 goes from the caliper to the rubber brake line. That rubber brake line then goes to the hard brake line that goes all the way to the master cylinder.

As long as there are no kinks/cracks in the main brake line, it may need a new fitting on the end. By cutting off the flared end and putting a new flare nut on, and re-flaring the end.

Is it possible for you to take a picture of where you wiped it clean?

I can. Where the lower control arm connects to the cross member is where it is wet with brake fluid. I'm assuming as the pedal is pressed while braking, the brake line is spraying on to the frame, then dripping down to the lower control arm connection to the cross member.

My question is, how do I get to that brake line you're describing?
My hands can't fit from the wheel well and there's no access from the engine bay.
I'm trying to find a way to access the line you speak of that goes runs on the frame by the steering rack.

How can I access that?

I would greatly appreciate it if someone can guide me on how to access that specific line.

Thanks for the info!

[drewusmaximus]

Quick question... Is that brake line fastened to the body of the car, or is it only fastened where it meets with the flex hose? I'm wondering if I loosen it from the brake hose will it move and all I have to do is loosen it from the ABS module?
I am assuming the brake line is fastened somewhere in its path from the brake hose to the ABS module. If I am wrong, I can then just loosen the line form the brake hose, move it a little to see where it connects to the ABS module and loosen it on that end, then inspect line..

Thanks in advance.

[drewusmaximus]

Does anyone know where the rear passenger brake line runs to the front? Does it run on the frame? Where does it bend up to go toward the engine?

[drewusmaximus]

Does anyone know where the rear passenger brake line runs to the front? Does it run on the frame? Where does it bend up to go toward the engine?

I had an appt to take it to a shop so they can find the leak. Unfortunately, I could barely stop the car at 5mph. I turned around 150 feet away and drove back in my driveway. I put it in the Ramos in hopes I can trace the lines but, could not find it. I went under the car and can see the passenger side lower control arm and crissmember wet with brake fluid but, still can’t find the lines, except for the one that connects to the from brake hose, and that’s hidden on the other side of the body. But, I feel as if the rear passenger line is the one that’s leaking. I just can’t find it and I can’t find a schematic anywhere on the net.

I can’t take anymore time off from work. I only have the weekend to work on it. I will be shocked if Audi made it that difficult to access the brake lines. I just don’t know where to look.