ABS Master Cylinder, 92 Chev Lumina

[Mark Gibson]

Greetings again Gentlemen,

Question for you on a 92 Chev Lumina, 3.1 liter, with ABS Brakes. When the car is cold, and you go to press the brakes the 1st few times, the pedal will sometimes go to the floor, and you can pump them a couple of times and get a good pedal. Its intermitenet. Pull all 4 wheels, callipers and wheels cylinders are all dry, and plenty of pad and shoe material left. The Master Cylinder has what I assume is the anti lock brake system attached to it. Has 2 electrical connections, and 3 bleeder valves on the top.
If it didn't have the ABS on the master cylinder, there would be no question for me, I'd replace the master cylinder right away, and bleed the system. What I am not sure of does the ABS system cause my problem, or is it the seals and piston in the MC? Also, when you replace the ABS MC, does it come with the ABS attachement on the rebuild MC, or do you need to do maint on the ABS piece thats on the side of the MC?

As always, I appreciate your help and advice. Hope all is well.....

Liv4Racin
Mark Gibson
Jax, FL

[way2old]

Hello Mark. Looks like it is not gonna be too much fun. Here is the written procedure.

WARNING: To avoid personal injury, due to a retained load on the modulator assembly, the "Gear Tension Relief" function of the TECH 1 scan tool must be performed prior to removal of the brake control and motor assembly.

REMOVE OR DISCONNECT


Using the TECH 1, perform gear tension relief procedure.
Air cleaner assembly.
Upper fuel lines and set aside.
Two solenoid electrical connectors.
Fluid level sensor electrical connector.
6-Pin motor pack electrical connector.
Four brake pipes by placing a shop cloth on top of motor pack (figure 2) to catch any dripping fluid and plug open lines to prevent fluid loss and/or contamination.
Two nuts attaching ABS hydraulic modulator and master cylinder assembly to vacuum booster. NOTE: It may be necessary to remove vacuum check valve from vacuum booster to gain access to the nut closest to the check valve.
ABS hydraulic modulator and master cylinder assembly from vehicle.
INSTALL OR CONNECT


ABS hydraulic modulator and master cylinder assembly in vehicle.
Two nuts attaching ABS hydraulic modulator and master cylinder assembly to vacuum booster and tighten to 27 Nm (20 lb ft) .
Four brake pipes to ABS hydraulic modulator assembly and tighten tube nuts to32 Nm (24 lb ft) .
Motor pack 6-Pin electrical connector.
Fluid level sensor electrical connector.
Two solenoid electrical connectors.
Upper fuel lines.
Air cleaner assembly.
Bleed system, refer to Brake Bleeding / Service and Repair .

[Mark Gibson]

I appreciate the advice..........Looks like an all day job for me!

Have a great day!

MG

[way2old]

You might go here and check the ABS section also. Good luck.
www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/0e/e3/90/0900823d800ee390.jsp

[Mark Gibson]

Guys,

I am not sure what we are referring to with this instruction. My Chevy tools frm back in my racing days, was a good timing light, Tach and Dwell meter, and a good set of Craftsman Tools. I am not sure what a Tech 1 tool is to perform this procedure:

WARNING: To avoid personal injury, due to a retained load on the modulator assembly, the "Gear Tension Relief" function of the TECH 1 scan tool must be performed prior to removal of the brake control and motor assembly.

Is it like an OBDII scan tool for late model chevys, that you perform the "Gear Tension Relief" within the cars PCM? Other then that, I can do the rest of the job, no problem.

Thanks again for the advice!

MG

[way2old]

The Tech II is GM's scan tool. You may be able to use another one to relieve the pressure. On some makes you can relieve the pressure by turning off ignition and depressing the pedal about 50 times. Good luck again.