1992 Buick Park Avenue Changed Master cylinder, no fluid fr

1916 PEERLESS

MEMBER
1992 BUICK PARK AVENUE
6 CYL
FWD
AUTOMATIC
189,654 MILES

This started when the ABS light came on, car still drove fine, then had to pump brakes to get a full pedal, then pumping pedal didn't work, pedal went to floor, no visable fluid leaks anywhere, I bought a new M/C, got as far as basically bench bleeding it on the car, the port for the line at the front end of the M/C has bled ok, rear port - no fluid, no air, nothing, there is a hose going from the resovoir down to the ABS UNIT, it appears dry as does the remainder of the system.
Other than this, the car has been great.

1 Reply

MERLIN2021

MECHANIC
17,250 POSTS

First step should have been scanning for the ABS code, may not have needed the master! Then bench bleeding these quick take up masters requires the knowledge that between stroke, count 15 seconds so it can refil itself, and NEVER pump a quick take up! Did you do this? I NEVER bench bleed on the car, you probably didnt bleed it right, so remove it and bench bleed it in a vise! I use brass plugs screwed into the ports, push in bore, and release count 15 and push again, repeat until the pisto wont move, mount on car, attach lines, push brake pedal, close lines, release pedal, count 15, repeat until all air is gone, DONT let it run out of fluid while bleeding, Then bleed system by opening all bleeders, when they start to drip, close them, then bleed by pressing pedal, open bleeder, close bleeder, and release pedal, count 15. Repeat at all wheels until all air is gone. If ABS light is on when your done, scan for codes. Here's the book directions, compare to mine:
BLEEDING BRAKE SYSTEM MANUAL BLEEDING Master Cylinder 1. With engine off, pump brake pedal several times to deplete vacuum reserve in brake booster. Remove brake fluid reservoir cap, and add fluid, if necessary, to fill reservoir to full mark. Replace reservoir cap. 2. Loosen forward (secondary) brake line fitting at master cylinder. Allow fluid to flow from fitting port while maintaining correct fluid level. Tighten forward brake line fitting. Slowly depress brake pedal once and hold. Loosen forward fitting, and allow air to be bled out. Tighten fitting. Slowly release brake pedal. 3. Wait 15 seconds. Repeat step 2), if necessary, until all air is purged. Tighten brake line fitting to specification. See TORQUE SPECIFICATIONS. Repeat procedure for master cylinder rearward (primary) brake line fitting. Brake Lines 1. Raise and support vehicle. Remove bleeder cap from right rear wheel bleeder valve. Attach hose to bleeder valve. Submerge other end of hose in container of clean brake fluid. 2. Using Brake Bleeder Wrench (J-21472) or (J-28434), loosen bleeder valve while an assistant presses brake pedal to its full travel. Hold brake pedal in depressed position, and close bleeder valve. 3. Slowly release brake pedal. Wait 15 seconds, and then repeat operation until no air bubbles emerge from submerged end of hose. Repeat procedure for remaining wheels in following sequence: left rear, right front then and left front. Tighten bleeder valves to specification. See TORQUE SPECIFICATIONS. NOTE: Rapid pumping of brake pedal causes master cylinder secondary piston to move into a position that makes bleeding system difficult.
1/15/2010 .