Lift my foot and make a second application the pedal goes to the floor

Tiny
SMILES30
  • MEMBER
  • 2006 PONTIAC GRAND PRIX
  • 3.7L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 141,000 MILES
GT model. On first brake application everything is fine but if I need to lift my foot and make a second application the pedal goes to the floor. Still stops but is not right. Was thinking it could be the master cylinder or brake booster as I have checked all brakes and calipers and bleed the brakes already. Any ideas?
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Monday, July 30th, 2018 AT 9:53 AM

18 Replies

Tiny
WALLY AB
  • MEMBER
  • 62 POSTS
I would check for leaks. Make sure the sliders and everything air fine. Replace old brake fluid and bleeding can help. If it still goes to the floor with everything checked, chances are the master cylinder seals are starting to go. I would suspect there is air in the lines. These guides can help you fix it.

https://youtu.be/w7gUsj2us0U

and

https://youtu.be/WDxvEQrMkBg

and

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

Please run down these guides and report back.
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Monday, July 30th, 2018 AT 11:24 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good afternoon.

Yes, the master cylinder could be the issue. When the pedal goes to the floor, if you let up and hit it hard, does the pedal hold? If it does then it has bad seals internally. If it does not, then you may have another issue. Roy
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Monday, July 30th, 2018 AT 12:37 PM
Tiny
TIPP29
  • MEMBER
  • 1 POST
  • 2005 PONTIAC GRAND PRIX
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 98,000 MILES
I got my brakes changed about a month ago, I took my car back a week later because of the squeaks. They then turned my rotors, that didn't stop the squeak, but then a couple days ago my pedal all of a sudden went slowly to the floor. Today I took it to another brake shop and when they put it on the lift my rotors were so messed up where they didn't cut them right. So now they're paying for someone else to turn my rotors or possible buy new ones. So wld the rotors have anything with pedal slowly going to the floor? Oh I got them bled today as well but the pedal still goes way down. Help!
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Tuesday, March 16th, 2021 AT 5:12 PM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
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Good morning,

This sounds like the master cylinder has failed and is leaking internally and holding pressure.

https://www.2carpros.com/articles/how-to-replace-a-brake-master-cylinder

https://www.2carpros.com/articles/how-to-bleed-or-flush-a-car-brake-system

I would have the master cylinder replaced.

Roy

Master Cylinder Replacement
Removal Procedure

Caution: Refer to Brake Fluid Irritant Caution in Service Precautions.

Notice: Refer to Brake Fluid Effects on Paint and Electrical Components Notice in Service Precautions.

imageOpen In New TabZoom/Print

1. Disconnect the electrical connector from the brake fluid level sensor.
2. Disconnect the brake pipes from the master cylinder.

3. Important: Install a rubber cap or plug to the exposed brake pipe fitting ends in order to prevent brake fluid loss and contamination.

Plug the open brake pipe ends.
4. Remove master cylinder mounting nuts.
5. Remove the master cylinder from the vehicle.
6. Drain the master cylinder reservoir of all brake fluid.

Installation Procedure

imageOpen In New TabZoom/Print

1. Bench bleed the master cylinder.
2. Install the master cylinder to the vacuum brake booster.

3. Notice: Refer to Fastener Notice in Service Precautions.

Install the master cylinder mounting nuts.
Tighten the master cylinder mounting nuts to 33 Nm (24 ft. lbs.).
4. Remove the plugs from the brake pipes
5. Connect the brake pipes to the master cylinder.
With ABS tighten the brake pipe fittings at the master cylinder to 30 Nm (22 ft. lbs.).
Without ABS tighten the front brake fittings to 27 Nm (20 ft. lbs.).
Without ABS tighten the rear brake fittings to 25 Nm (18 ft. lbs.).
6. Connect the electrical connector to the brake fluid level sensor.
7. Bleed the brake system.
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Tuesday, March 16th, 2021 AT 5:12 PM (Merged)
Tiny
JOHN35069
  • MEMBER
  • 5 POSTS
  • 2004 PONTIAC GRAND PRIX
  • V6
  • 2WD
  • AUTOMATIC
  • 200,450 MILES
Hello, I've replaced front and back brakes on my car and now the pedal goes to the floor. There are no leaks anywhere, but when I push my brake pedal in you can hear air in the brake booster like it is leaking. The car had brakes two weeks ago when I bought it.
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Tuesday, March 16th, 2021 AT 5:12 PM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
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Good afternoon,

Did you replace anything else in the system? Did you run out of fluid during the repair making it necessary for the system to be bled?

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

It sounds like the master cylinder has failed.

Roy
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Tuesday, March 16th, 2021 AT 5:12 PM (Merged)
Tiny
JOHN35069
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  • 5 POSTS
No I kept it full of fluid.
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Tuesday, March 16th, 2021 AT 5:12 PM (Merged)
Tiny
ASEMASTER6371
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Okay, did you bleed the system?

Did you open the bleeders on the calipers?

Roy
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Tuesday, March 16th, 2021 AT 5:12 PM (Merged)
Tiny
JOHN35069
  • MEMBER
  • 5 POSTS
Yes, I did. I was told by my wife's step father to bleed them again, but all four at the same time and loosen the cap on the master cylinder and let it gravity bleed them self's for an hour. I did that and still no change.
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Tuesday, March 16th, 2021 AT 5:12 PM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Okay, that is not the way to do it at all. By cracking the line at the master, you may have allowed air into the system. You have ABS and if air got in there, you need to do a procedure for bleeding the ABS. The procedure tells you to crack the line at the master for under a minute, not an hour.

Roy

Automated brake bleed for ABS

Bleeding the ABS System

Caution: Refer to Brake Fluid Irritant in Service Precautions.
See: Brakes and Traction Control > Technician Safety Information > Brake Fluid Irritant Caution

Notice:Refer to Brake Fluid Effects on Paint and Electrical Components in Service Precautions.
See: Brakes and Traction Control > Vehicle Damage Warnings > Brake Fluid Effects on Paint and Electrical Components Notice

Perform a manual or pressure bleeding procedure. Refer to Hydraulic Brake System Bleeding (Manual) or Hydraulic Brake System Bleeding (Pressure) in Hydraulic Brakes. If the desired brake pedal height results are not achieved, perform the automated bleed procedure.

The procedure cycles the system valves and runs the pump in order to purge the air from the secondary circuits normally closed off during normal base brake operation and bleeding. The automated bleed procedure is recommended when air ingestion is suspected in the secondary circuits, or when the BPMV has been replaced.

Automated Bleed Procedure

Notice:The Auto Bleed Procedure may be terminated at any time during the process by pressing the EXIT button. No further Scan Tool prompts pertaining to the Auto Bleed procedure will be given. After exiting the bleed procedure, relieve bleed pressure and disconnect bleed equipment per manufacturers instructions. Failure to properly relieve pressure may result in spilled brake fluid causing damage to components and painted surfaces.

1. Raise the vehicle on a suitable support. Refer to Vehicle Lifting.
2. Remove all four tire and wheel assemblies. Refer to Tire and Wheel Removal and Installation.
3. Inspect the brake system for leaks and visual damage. Refer to Brake Fluid Loss or Symptoms - Hydraulic Brakes. Repair or replace as needed.
4. Inspect the battery state of charge. Refer to Battery Inspection/Test.
5. Install a scan tool.
6. Turn ON the ignition, with the engine OFF.
7. With the scan tool, establish communications with the EBCM. Select Special Functions. Select Automated Bleed from the Special Functions menu.
8. Bleed the base brake system. Refer to Hydraulic Brake System Bleeding (Manual) or Hydraulic Brake System Bleeding (Pressure) in Hydraulic Brakes.
9. Follow the scan tool directions until the desired brake pedal height is achieved.
10. If the bleed procedure is aborted, a malfunction exists. Perform the following steps before resuming the bleed procedure:
- If a DTC is detected, refer to Diagnostic Trouble Code (DTC) List and diagnose the appropriate DTC.
- If the brake pedal feels spongy, perform the conventional brake bleed procedure again. Refer to Hydraulic Brake System Bleeding (Manual) or Hydraulic Brake System Bleeding (Pressure) in Hydraulic Brakes.

11. When the desired pedal height is achieved, press the brake pedal in order to inspect for firmness.
12. Remove the scan tool.
13. Install the tire and wheel assemblies. Refer to Tire and Wheel Removal and Installation.
14. Inspect the brake fluid level. Refer to Master Cylinder Reservoir Filling in Hydraulic Brakes.
15. Road test the vehicle while inspecting that the pedal remains high and firm.

Manual bleeding after automated.

Caution: Refer to Brake Fluid Irritant in Service Precautions.
See: Brakes and Traction Control > Technician Safety Information > Brake Fluid Irritant Caution

Notice:When adding fluid to the brake master cylinder reservoir, use only Delco Supreme II, GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container. The use of any type of fluid other than the recommended type of brake fluid, may cause contamination which could result in damage to the internal rubber seals and/or rubber linings of hydraulic brake system components.

Notice:Refer to Brake Fluid Effects on Paint and Electrical Components in Service Precautions.
See: Brakes and Traction Control > Vehicle Damage Warnings > Brake Fluid Effects on Paint and Electrical Components Notice

1. Place a clean shop cloth beneath the brake master cylinder to prevent brake fluid spills.
2. With the ignition OFF and the brakes cool, apply the brakes 3-5 times, or until the brake pedal effort increases significantly, in order to deplete the brake booster power reserve.
3. If you have performed a brake master cylinder bench bleeding on this vehicle, or if you disconnected the brake pipes from the master cylinder, you must perform the following steps:
3.1. Ensure that the brake master cylinder reservoir is full to the maximum-fill level. If necessary, add Delco Supreme II, GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
If removal of the reservoir cap and diaphragm is necessary, clean the outside of the reservoir on and around the cap prior to removal.
3.2. With the rear brake pipe installed securely to the master cylinder, loosen and separate the front brake pipe from the front port of the brake master cylinder.
3.3. Allow a small amount of brake fluid to gravity bleed from the open port of the master cylinder.
3.4. Reconnect the brake pipe to the master cylinder port and tighten securely.
3.5. Have an assistant slowly depress the brake pedal fully and maintain steady pressure on the pedal.
3.6. Loosen the same brake pipe to purge air from the open port of the master cylinder.
3.7. Tighten the brake pipe, then have the assistant slowly release the brake pedal.
3.8. Wait 15 seconds, then repeat steps 3.3-3.7 until all air is purged from the same port of the master cylinder.
3.9. With the front brake pipe installed securely to the master cylinder - after all air has been purged from the front port of the master cylinder - loosen and separate the rear brake pipe from the master cylinder, then repeat steps 3.3-3.8.
3.10. After completing the final master cylinder port bleeding procedure, ensure that both of the brake pipe-to-master cylinder fittings are properly tightened.

4. Fill the brake master cylinder reservoir with Delco Supreme II, GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container. Ensure that the brake master cylinder reservoir remains at least half-full during this bleeding procedure. Add fluid as needed to maintain the proper level.
Clean the outside of the reservoir on and around the reservoir cap prior to removing the cap and diaphragm.

5. Install a proper box-end wrench onto the RIGHT REAR wheel hydraulic circuit bleeder valve.
6. Install a transparent hose over the end of the bleeder valve.
7. Submerge the open end of the transparent hose into a transparent container partially filled with Delco Supreme II, GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
8. Have an assistant slowly depress the brake pedal fully and maintain steady pressure on the pedal.
9. Loosen the bleeder valve to purge air from the wheel hydraulic circuit.
10. Tighten the bleeder valve, then have the assistant slowly release the brake pedal.
11. Wait 15 seconds, then repeat steps 8-10 until all air is purged from the same wheel hydraulic circuit.
12. With the right rear wheel hydraulic circuit bleeder valve tightened securely - after all air has been purged from the right rear hydraulic circuit - install a proper box-end wrench onto the LEFT FRONT wheel hydraulic circuit bleeder valve.
13. Install a transparent hose over the end of the bleeder valve, then repeat steps 7-11.
14. With the left front wheel hydraulic circuit bleeder valve tightened securely - after all air has been purged from the left front hydraulic circuit - install a proper box-end wrench onto the LEFT REAR wheel hydraulic circuit bleeder valve.
15. Install a transparent hose over the end of the bleeder valve, then repeat steps 7-11.
16. With the left rear wheel hydraulic circuit bleeder valve tightened securely - after all air has been purged from the left rear hydraulic circuit - install a proper box-end wrench onto the RIGHT FRONT wheel hydraulic circuit bleeder valve.
17. Install a transparent hose over the end of the bleeder valve, then repeat steps 7-11.
18. After completing the final wheel hydraulic circuit bleeding procedure, ensure that each of the 4 wheel hydraulic circuit bleeder valves are properly tightened.
19. Fill the brake master cylinder reservoir to the maximum-fill level with Delco Supreme II, GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
20. Slowly depress and release the brake pedal. Observe the feel of the brake pedal.
21. If the brake pedal feels spongy, repeat the bleeding procedure again. If the brake pedal still feels spongy after repeating the bleeding procedure, perform the following steps:
21.1. Inspect the brake system for external leaks. Refer to Brake System External Leak Inspection.
21.2. Pressure bleed the hydraulic brake system in order to purge any air that may still be trapped in the system.
22. Turn the ignition key ON, with the engine OFF. Check to see if the brake system warning lamp remains illuminated.

Important:DO NOT allow the vehicle to be driven until it is diagnosed and repaired.

23. If the brake system warning lamp remains illuminated. Refer to Symptoms - Hydraulic Brakes.
See: Hydraulic System, Brakes > Symptom Related Diagnostic Procedures
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Tuesday, March 16th, 2021 AT 5:13 PM (Merged)
Tiny
JOHN35069
  • MEMBER
  • 5 POSTS
My car does not have ABS on it at all it.
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Tuesday, March 16th, 2021 AT 5:13 PM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Okay, good. Most cars that year had ABS.

Just follow the manual bleeding. If you still have no pedal, then you need a master cylinder.

Roy
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Tuesday, March 16th, 2021 AT 5:13 PM (Merged)
Tiny
JOHN35069
  • MEMBER
  • 5 POSTS
Okay, thank you.
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Tuesday, March 16th, 2021 AT 5:13 PM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
You are welcome.

Always glad to help.

Roy
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Tuesday, March 16th, 2021 AT 5:13 PM (Merged)
Tiny
NJPAMPINELLA
  • MEMBER
  • 4 POSTS
  • 2000 PONTIAC GRAND PRIX
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
I just changed my front pads & rotors for my first time by myseff. I did everything as I was instructed & everything went on perfectlly. When the job was completed I put the cap back on the master cylender, started her up & pumped the pedal several times. Now I have NO brakes! NO pedal at all! It goes straight to the floor no matter how many times I pump it. It seems like the caliper pistons aren't compressing. I don't see any fluid leaking other than what came out from the resevoir when I initially compressed the pistons. The only problem I encountered was when I took off the caliper pins, they were super difficult to pull out & had a bunch of crusty old anti seize & dryed up grease caked on them. There was nothin "freely" about the way they moved! On the drivers side, there were plastic bushings that pulled out on the end of the pins but the passenger side pins came out without the bushings. Could this be why I have no brakes anymore or do I have 2 seperate problems? Any suggestions?
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Tuesday, March 16th, 2021 AT 5:13 PM (Merged)
Tiny
MMPRINCE4000
  • MECHANIC
  • 8,549 POSTS
If you did not remove the caliper lines or any lines to the brakes, you either have a leak somewhere or a bad MC.

The slide pins should move freely, if stuck they will not release and cause the pad to wear.

Bleed the brakes, all four of them, start with farthest from MC and work your up to closest to MC. If you still have no pedal, then leak or MC.
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Tuesday, March 16th, 2021 AT 5:13 PM (Merged)
Tiny
NJPAMPINELLA
  • MEMBER
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I manually bled all 4 lines. I started with the passenger rear then driver rear, passenger front, driver front. At first. Nothing! After about 9 times of crackin the bleeder a tiny bit of fluid came from the passenger rear & the driver front. I got absolutely nothing out of the driver rear or the passenger front. I thought it could possibly be that the bleeders were clogged so I gravity bled them. Still nothing from those 2 calipers. I can actually stop the car now but there isnt any pressure behind the pedal & my stopping distance is for S**t! I thoroughly inspected the undercarriage with a flashlight & there is no fluid leaking from anywhere. I had the ABS system scanned & no codes came up. Still think it's the master?
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Tuesday, March 16th, 2021 AT 5:13 PM (Merged)
Tiny
MMPRINCE4000
  • MECHANIC
  • 8,549 POSTS
If you cannot get fluid to flow from the bleed screws, either there is a clogged up line or the MC is leaking internally.

When installing a new MC, bench bleed it before install.
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Tuesday, March 16th, 2021 AT 5:13 PM (Merged)

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