After new calipers the brake pedal goes to floor after multiple bleeds... help!

[cgsportsmen]

1st post!

Hi guys, I just spent the weekend putting 4 new calipers on the wife's 2007 Z71 Tahoe. The swaps went fairly easy. The bleeder valves are on top and everything looks correct with no leaks.

My problem is that even after multiple bleeds, starting at Right-Rear then Left-Rear then Right-Front then Left-Front, the brake pedal goes straight to the floor?!? My dad and I spent hours bleeding them and still no pedal?!

They seem to pump up without the car running but as soon as u crank the vehicle all pedal is lost and it goes to the floor. I moved the car to see how good the brakes were and it is definitely not drivable at this point... IMO.

ANY help would be appreciated, as I need this vehicle back on the road asap because my wife returns back to work next week after having out 1st Daughter this past December.

Thanks guys!

 

[thompsoj22]

if it's possible that in your multiple bleed,s that the master cyl fluid level dropped to the point of allowing air to enter than thats your culprit and you will have to bleed that component first. sounds like you have simply got air up top, such a simple task can be such a PITA. someone else will respond and maybe have a method/trick of avoiding the bench bleed and be able to do it in place? are you doing an old school pump the pedal and open the bleeder?

 

[cgsportsmen]

Yes, we were pumping the pedal and opening the bleeder valves to bleed all 4 corners in order.

We were constantly monitoring the fluid in the reservoir and I am fairly certain that it did not get below the "Minimum" mark on the tank.

 

[swathdiver]

1st post!

Hi guys, I just spent the weekend putting 4 new calipers on the wife's 2007 Z71 Tahoe. The swaps went fairly easy. The bleeder valves are on top and everything looks correct with no leaks.

My problem is that even after multiple bleeds, starting at Right-Rear then Left-Rear then Right-Front then Left-Front, the brake pedal goes straight to the floor?!? My dad and I spent hours bleeding them and still no pedal?!

They seem to pump up without the car running but as soon as u crank the vehicle all pedal is lost and it goes to the floor. I moved the car to see how good the brakes were and it is definitely not drivable at this point... IMO.

ANY help would be appreciated, as I need this vehicle back on the road asap because my wife returns back to work next week after having out 1st Daughter this past December.

Thanks guys!

Hydraulic Brake System Bleeding (Manual)

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:

1. Ensure that the brake master cylinder reservoir is full to the maximum-fill level. If necessary add GM approved brake fluid from a clean, sealed brake fluid container. Refer to Fluid and Lubricant Recommendations (See: Maintenance\Specifications). If removal of the reservoir cap and diaphragm is necessary, clean the outside of the reservoir on and around the cap prior to removal.
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. Allow a small amount of brake fluid to gravity bleed from the open port of the master cylinder.
4. Reconnect the brake pipe to the master cylinder port and tighten securely.
5. Have an assistant slowly depress the brake pedal fully and maintain steady pressure on the pedal.
6. Loosen the same brake pipe to purge air from the open port of the master cylinder.
7. Tighten the brake pipe, then have the assistant slowly release the brake pedal.
8. Wait 15 seconds, then repeat steps 3.3-3.7 until all air is purged from the same port of the master cylinder.
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.
10. After completing the final master cylinder port bleeding procedure, ensure that both of the brake pipe-to-master cylinder fittings are properly tightened.

1. Fill the brake master cylinder reservoir with GM approved brake fluid from a clean, sealed brake fluid container. Refer to Master Cylinder Reservoir Filling (See: Hydraulic System\Brake Master Cylinder\Service and Repair\Procedures\Master Cylinder Reservoir Filling). 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.
2. Install a proper box-end wrench onto the RIGHT REAR wheel hydraulic circuit bleeder valve.
3. Install a transparent hose over the end of the bleeder valve.
4. Submerge the open end of the transparent hose into a transparent container partially filled with GM approved brake fluid from a clean, sealed brake fluid container. Refer to Fluid and Lubricant Recommendations (See: Maintenance\Specifications).
5. Have an assistant slowly depress the brake pedal fully and maintain steady pressure on the pedal.
6. Loosen the bleeder valve to purge air from the wheel hydraulic circuit.
7. Tighten the bleeder valve, then have the assistant slowly release the brake pedal.
8. Wait 15 seconds, then repeat steps 8-10 until all air is purged from the same wheel hydraulic circuit.
9. 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 REAR wheel hydraulic circuit bleeder valve.
10. Install a transparent hose over the end of the bleeder valve, then repeat steps 7-11.
11. With the left rear wheel hydraulic circuit bleeder valve tightened securely, after all air purged from the left rear hydraulic circuit, install a proper box-end wrench onto the RIGHT FRONT wheel hydraulic circuit bleeder valve.
12. Install a transparent hose over the end of the bleeder valve, then repeat steps 7-11.
13. With the right front wheel hydraulic circuit bleeder valve tightened securely, after all air has been purged from the right front hydraulic circuit, install a proper box-end wrench onto the LEFT FRONT wheel hydraulic circuit bleeder valve.
14. Install a transparent hose over the end of the bleeder valve, then repeat steps 7-11.
15. After completing the final wheel hydraulic circuit bleeding procedure, ensure that each of the 4 wheel hydraulic circuit bleeder valves are properly tightened.
16. Fill the brake master cylinder reservoir to the maximum-fill level with GM approved brake fluid from a clean, sealed brake fluid container. Refer to Master Cylinder Reservoir Filling (See: Hydraulic System\Brake Master Cylinder\Service and Repair\Procedures\Master Cylinder Reservoir Filling).
17. Slowly depress and release the brake pedal. Observe the feel of the brake pedal.
18. 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:

1. Inspect the brake system for external leaks. Refer to Brake System External Leak Inspection (See: Hydraulic System\Testing and Inspection\Component Tests and General Diagnostics).
2. Pressure bleed the hydraulic brake system in order to purge any air that may still be trapped in the system.

1. Turn the ignition key ON, with the engine OFF. Check to see if the brake system warning lamp remains illuminated.

Note: If the brake system warning lamp remains illuminated, DO NOT allow the vehicle to be driven until it is diagnosed and repaired.

 

[iamdub]

If you pushed the brake pedal to the floor with an original master cylinder with high miles, you could've damaged the seals in it. I did this when flushing and bleeding my '08. Bleeding was going great until I got to the front left caliper and that's when the pedal went soft and wouldn't firm up. A new MC with reservoir was only about $10 more than a rebuilt one at O'Reilly. I now lay a 2x4 in the floorboard to keep the pedal from bottoming out when bleeding brakes.

 

[trailblazer]

Find someone with a Tech II or bidirectional scan tool and run the ABS bleed process. I had a similar issue (and I have a Tech II) and it made a considerable difference. I believe my issue was ingesting some air in the system while manually bleeding.

 

[cgsportsmen]

Find someone with a Tech II or bidirectional scan tool and run the ABS bleed process. I had a similar issue (and I have a Tech II) and it made a considerable difference. I believe my issue was ingesting some air in the system while manually bleeding.

This is what I have concluded also... I have a friend bringing his snap-on tomorrow evening and will update!

Thanks for input!

 

[Shawn1112]

Very curious to see what the issue is.
Good luck