1997 Chevy Lumina Spongy brakes

Tiny
JENKINS1616
  • MEMBER
  • 1997 CHEVROLET LUMINA
Brakes problem
1997 Chevy Lumina Front Wheel Drive Automatic 205172 miles

I just put all new brakes on the front. New rotors, pads, and calipers. My dad and I bleed the 2 front ones, and the pedal was spongy so we bleed all 4, same thing, redid the 2 front and still the same thing. I can pump up the brakes without it running and they get hard but as soon as I start it they get spongy again. Could this be a bad master cylinder, vacuum leak, or what could it be?
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Wednesday, August 18th, 2010 AT 8:54 AM

9 Replies

Tiny
WRENCHTECH
  • EXPERT
Go back and look at the calipers and see if the bleeders are at the top or the bottom and let me know.
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Wednesday, August 18th, 2010 AT 9:29 AM
Tiny
JENKINS1616
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They are on the top just above the brake line.
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Wednesday, August 18th, 2010 AT 10:45 AM
Tiny
WRENCHTECH
  • EXPERT
What was the problem to start with? Why was all that stuff changed?
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Wednesday, August 18th, 2010 AT 11:56 AM
Tiny
JENKINS1616
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A few of the pistons in the caliper were seized, the pads and rotor were bad and needed it.
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Wednesday, August 18th, 2010 AT 12:18 PM
Tiny
JENKINS1616
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This is what ive been told through my own checking. Ive been told to try bench bleeding the master cylinder, I had another guy tell me of a trick he learned to possibly reset the ABS system by pumping the brakes then opening all 4 bleeder screws then close all of them, ive been told it may be a vacuum leak on my master cylinder as well. What do you suggests I try?
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+1
Wednesday, August 18th, 2010 AT 12:22 PM
Tiny
WRENCHTECH
  • EXPERT
A pressure bleeder will help a lot. There may also be a couple bleeder screws on the ABS unit too. You likely have an air pocket in the ABS unit that you have to get out.
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Wednesday, August 18th, 2010 AT 12:34 PM
Tiny
JENKINS1616
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Ok. Where would the ABS bleeder screws be located at? Do you know?
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Wednesday, August 18th, 2010 AT 1:24 PM
Tiny
WRENCHTECH
  • EXPERT
The bleeder screws are right on the hydraulic unit and very obvious.

Here are the factory bleeding instructions.

NOTE: Pressure bleeding equipment must be of the diaphragm type. It must have a rubber diaphragm between the air supply and the brake fluid to prevent air, moisture and other contaminants from entering the hydraulic system.

TOOLS REQUIRED:
J 29532 Diaphragm Type Brake Bleeder J 35589 Compact Brake Bleeder Adapter

1. Clean brake fluid reservoir cover and surrounding area.
2. Remove brake fluid reservoir cover.
3. Inspect brake fluid reservoir level. Add clean brake fluid as required.

4. Connect bleeder adapter J 35589 to brake fluid reservoir.
5. Connect bleeder adapter to pressure bleeding equipment.
6. Adjust pressure bleed equipment to 35 to 70 kPa (5 to 10 psi) and wait for approximately 30 seconds to ensure there is no leakage.
7. Adjust pressure bleed equipment to 205 to 240 kPa (30 to 35 psi).
8. Proceed as follows with pressure bleeding equipment connected and pressurized.

Brake Bleeding

1. Attach a clear plastic bleeder hose to the rearward bleeder valve on the brake modulator. Submerge opposite hose end in a clean container partially filled with clean brake fluid.
2. Slowly open bleeder valve and allow fluid to flow until no air is seen in fluid.
3. Close valve when fluid flows without any air bubbles.
4. Repeat Steps 8B and 8C until no air bubbles are present.
5. Relocate the bleeder hose on the forward brake modulator bleeder valve and repeat Steps 8A through 8D. Tighten Antilock Brake System(ABS ) brake modulator bleeder valves to 9 Nm (80 inch lbs.) CAUTION: Use a shop cloth to catch escaping brake fluid. Take care to prevent fluid from running down motor pack base or into the electrical connector. Also, do not allow brake fluid to contact any painted surfaces as surface damage will occur. If brake fluid does contact any surface, flush surface with water to lessen damage.

9. Proceed to bleed the brake modulator brake pipe connections with pressure bleeding equipment connected and pressurized:

1. Slowly open forward brake pipe tube nut on brake modulator and check for air in escaping fluid.
2. When air flow ceases, immediately tighten tube nut. Tighten tube nut to modulator 24 Nm (18 ft. Lbs.).
3. Repeat Step 9 for remaining three brake pipe connections, moving from front to rear.

10. Raise vehicle and suitably support.
11. Proceed to bleed wheel brakes in sequence shown Bleed sequence: Right rear. Left front. Left rear. Right front.

1. Attach a clear plastic bleeder hose to bleeder valve at the wheel and submerge opposite hose end in clean container partially filled with clean brake fluid.
2. Slowly open bleeder valve and allow fluid to flow.
3. Close valve when fluid begins to flow without any air bubbles. Tap lightly on the caliper or backing plate to dislodge any trapped air bubbles.

12. Perform Step 13 on right rear wheel brake.
13. Repeat Step 13 on left front wheel brake.
14. Repeat Step 13 on left rear wheel brake.
15. Repeat Step 13 on right front wheel brake.
16. Tighten Bleeder valves:

o (Front Caliper) to 13 Nm (115 inch lbs.).

O (Rear Caliper) to 7 Nm (62 inch lbs.).

O (Rear Wheel Cylinder) to 7 Nm (62 inch lbs.).

NOTE
Be sure the bleeder valves do not leak.

17. Remove pressure bleeding equipment, including Bleeder Adapter, J 35589.
18. Lower vehicle.
19. Inspect Brake fluid level in reservoir and fill to proper level if necessary.
20. Reinstall brake fluid reservoir cap.

INSPECT

1. Turn the ignition to the "RUN" position, turn engine off. Apply brake pedal with moderate force and hold. Note pedal travel and feel.

O If pedal feels firm and constant and pedal travel is not excessive, start the engine. With the engine running, re-check the pedal travel. If it's still firm and constant and pedal travel is not excessive, go to Step B.
O If pedal feels soft or has excessive travel either initially or after engine start, the following procedure may be used. With the Scan Tool, release then apply each motor 2 to 3 times and cycle each solenoid 5 to 10 times. When finished, be sure to apply the front and rear motors to ensure the pistons are in the upmost position. DO NOT DRIVE THE VEHICLE. If a Scan Tool is not available, remove foot from brake pedal, start the engine and allow it to run for at least 10 seconds to initialize the ABS. DO NOT DRIVE THE VEHICLE. After 10 seconds, turn the ignition off. This initialization procedure MUST be repeated 5 times to ensure any trapped air has been dislodged. Now repeat bleeding procedure starting at Step 1.

2. Road test the vehicle.

O Make several normal (non-ABS) stops from a moderate speed to ensure proper brake system function. Allow adequate cooling time between stops.
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Wednesday, August 18th, 2010 AT 1:33 PM
Tiny
JENKINS1616
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Ok. I will try this as soon as I find someone with a pressure bleeder. Thank you
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Wednesday, August 18th, 2010 AT 1:57 PM

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