How to Test a Brake Line for Leaks

Leaking brake fluid is an unacceptable problem on any car. You will need to isolate each component area of the braking system to test it for leaks. The hydraulic pressure within the system should be sufficient to produce a discoverable leak when you push the brake pedal.

Instructions

1

Raise the hood and look for evidence of leaks around the master cylinder. It will be attached to the fire wall of the car above the engine to the far left or far right. Make sure the cap is in place and secure. Examine the lines running from the master cylinder for brake fluid leaks. Rusty or damaged areas are a place to pay special attention. If it appears that brake fluid has been leaking, have your helper push hard on the brakes and watch for brake fluid to ooze or spray out.

2

Inspect the back and front of each of the four wheels on the car for signs that brake fluid has been leaking. It will leave an oily residue and will probably be dirty from accumulated dust on the fluid. If a possible leak is noted on the rear of the wheel, examine the area where the brake lines enter the wheel cylinder assembly to see if the bleeder has been weeping. This is a fitting that will stick out from the area where the line connects. Have your helper depress the brakes and verify the leak.

3

Raise the car to access the brake lines underneath the vehicle. Isolate the area of the leak by clamping off the rubber tubes on the brake lines with vice grips or other type of clamping devices. Press on the brakes. If the brake pedal holds its position, you have eliminated the brake lines running to the four wheels. If the brake does not hold, make sure the master cylinder is full and push the brakes again while someone is under the car watching the brake lines until the leak is found. If the brakes hold on the previous test, release the clamp on one wheel at a time until the leak is discovered on one or more wheels. Use the lug wrench and remove the tire on the offending wheel to verify the precise location of the leak.