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Old 04-15-2019, 09:54 PM   #1
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Issue/Help with ABS/Master Cylinder Replacement

Replaced ABS and Brake Master Cylinder but left power bleeder pressurized (10psi) overnight. Found a puddle under the car and an empty bleeder. Noted a small leak at brass fitting on the bleeder; applied teflon and resealed. Began brake bleeding using INPA but my puddle grew and found fluid dripping under the car near the ABS and also mid-vehicle. Rechecked work and torqued brake fittings; looks good and no obvious signs of a leak. Seems to leak only if pressure is applied. Could use insight/advice on proceeding.

1. Only places I could see as possible leaks would be the brake reservoir or this pressure hose. My car has steel line except this one and I bent it rather sharply trying to get routed. Canít think of anything*else that might leak. Any suggestions?

2. Without brakes and needing parts, cannot power-wash for cleaning fluid under the ABS and where it might have run. Maybe Simple Green and garden hose?* Other suggestions?*

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Old 04-16-2019, 12:14 AM   #2
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Brake fluid can be rinsed off with just water. Clean it off the painted body right away. Garden hose is a good idea. Brake fluid is a good paint stripper. It will cause the paint to bubble right off. A leak in one of the lines will cause the pedal to slowly sink to the floor with foot pressure but if the reservoir is leaking, pedal will not go down. You should be able to locate the leak by following the fluid. Clean up the mess and re-pressurize the system. Brake fittings and bleeders are metal to metal flare type fittings that should not have sealant or tape but do require a certain amount of torque to properly seal. You don't want any of that stuff finding it's way into the abs hydraulic unit. Remove the Teflon tape, it will only cause problems. Just curious, why did you replace the master cylinder and abs? Did you replace the abs hydraulic unit or the control unit or both? Good luck, hope this helps.

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Old 04-16-2019, 12:29 AM   #3
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I had the same thing. After changing my master cylinder, I would see brake fluid leaking from under the car for a few days and my fluid level would go down. I tightened the fittings just to be safe but after driving carefully for a few days, it stabilized
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Old 04-17-2019, 12:43 AM   #4
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Thanks for the advice. I was able to isolate two leaky fittings on the ABS replacement by pressurizing with 15psi of air using a power bleeder and checking each fittings with a stethoscope. Learned to verify the brake system holds air before adding fluid.

Flummoxed by leaky brake fittings. Flare and seat appear fine and installed per spec. Multiple attempts to torqued, re-torque and even over-torque but stilling hearing micro leaks. Might replace line to master cylinder but other runs to front or rear brakes - and still don't know the root cause.

Leaning towards using flare gaskets; copper washers that sit inside the fitting and conform to the flare and seat when tightened.

Edit: Success! Will post DIY and link from here

Last edited by Bidno; 04-23-2019 at 12:26 PM.
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