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Randall C
Randall C, ASE Master Tech
Category: Chevy
Satisfied Customers: 11325
Experience:  ASE Master, L1, 32 years, Diagnostic / Electrical Specialist
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2007 Tahoe: rotors..brake fluid already and still getting air

Customer Question

just changed the brakes and turned the rotors on my 2007 Tahoe, right side bled fine, but the left (driver) side has air in the line... bled through 3 big bottles of brake fluid already and still getting air. Any suggestions?
Submitted: 4 years ago.
Category: Chevy
Expert:  Randall C replied 4 years ago.
The best way is to gravity bleed. Remove the master cap. leave OFF, fill with fluid. The open RIGHT REAR bleeder and wait till you see slow steady drip. Once dripping, let drip for a good while say 4 minutes. keep eye on fluid level. The you MUST do LEFT REAR same way, The RIGHT FRONT then lastly LEFT FRONT,. Critical you go in that order with ABS. If none of this works, then bleeding the hydraulic unit may be required but a little more tricky

below is the book mehtod which differs a little from what i am asking you to try. So.. try the "gravity bleed first"

  1. ill the brake master cylinder reservoir with Delco Supreme 11(R), 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.
  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 Delco Supreme 11(R), GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
  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 Delco Supreme 11(R), GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
  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.
  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. Important: If the brake system warning lamp remains illuminated, DO NOT allow the vehicle to be driven until it is diagnosed and repaired.
  2. If the brake system warning lamp remains illuminated, refer to Symptoms - Hydraulic Brakes.



 

Randall C, ASE Master Tech
Category: Chevy
Satisfied Customers: 11325
Experience: ASE Master, L1, 32 years, Diagnostic / Electrical Specialist
Randall C and 7 other Chevy Specialists are ready to help you
Customer: replied 4 years ago.
So gravity bleed was going great on rear two tires, then got to right front and never got a good slow steady drip even with the bleed valve well open. Should I move on to the secondary instructions with someone applying pressure to the brake while I bleed starting at the right rear again? nI gave each of the tires 5 minutes of good slow steady drip until the front right stopped dripping. The reservoir is full and cap is off.
Expert:  Randall C replied 4 years ago.
I should have asked before. What all did you change that led you to having to bleed the system?
Customer: replied 4 years ago.
I replaced the rotors (had them turned then reinstalled) and replaced front pads. The pads weren't even 1/4 worn when I had to pull the rotors which were grooved and causing a shudder when slowing from highway speeds.
Expert:  Randall C replied 4 years ago.
Thanks. I guess i was wondering why you opened the system hydraulics? did you take a line off, take a caliper off? trying to understand why you are at the bleeding stage? Sorry for questions but need to get the whole picture
Customer: replied 4 years ago.
So I bled the caliper open to be able to remove and replace the pads. Then I disconnected the disk brake assembly to be able to remove the rotor. Took the rotors to the shop to have them turned then reinstalled the rotors and the disk brake assembly. The two bolts for the brake assembly then the two bolts for the caliper. Then I bled the air out of the right side (front) not knowing originally that I had to bleed the rear tires even if I didn't touch those brakes. There was a little air the first two pump/ bleed cycles then two air free bleed cycles on the front right so I topped off the reservior again and went to bleed the left front and never had an air free cycle, some cycles were all air.

Now since I dont have the tools to complete a pressure bleed, I have taken it to the corner shop for them to pressure bleed the brakes and see if they can get the air out. I am just curious as to why this happened now? I am guessing it was something to do with how I replaced the pads, but I know of no other way to open the caliper enough to fit in the new pads without bleeding it open some. Of course when I say bleed it open I am referring to the method my father taught me of using a large flat head screwdriver and placing it through the hole in the caliper and gently applying pressure against the pad to rotor assemble (without messing up the rotor) and then opening the bleeder valve to express some fluid, close the valve, regrip and bleed again until there is sufficient space to install the new pads.

This is the first time I have ever experienced this issue and I am a bit concerned that there is no indicator light coming on to say "Hey dummy, you have no brakes" and the onstar diagnostics aren't picking up anything either. A bit concerning considering the truck will tell you when your tires are low or that you have a light out, but nothing when a major function is not working... ;-)
Expert:  Randall C replied 4 years ago.
I am sorry to hear you are having these troubles. Although my answer should be correct, it is very possible the problem was created by the method you used to compress the caliper. For future reference, do NOT undo a bleeder especially on ABS vehicles to depress the caliper. To compress you can use large screwdriver as you were taught to pry the piston back but keeping hard even pressure till it retracts. it may move very slow. the ideal way is to use a large C clamp. Insert just the inner old pad, put on C clamp and begin winding it in till piston retracts. it will. breaking open a hydraulic system is not gpood and cause problems as you have. What happens is whne you open the system, even though open, as you compress you are still pushing air back up through the ABS unit. This is where the problem comes in. If air gets trapped in the ABs unit, you have to use a scanner many times to activate ABS vlaves in order to bypass and resume bleeding normally.ABS systems can be tricky thus why we clamp off the rubber hose near caliper whenever we say ahve to change caliperr just to avoid this problem. they should? be able to pressure bleed it out. Just remember, never open the hydraulics unless you have to. In your case you made a simple mistake and can happen to the best of us. below is the procedure needed to bleed via ABS when ther is air there


  1. nstall a scan tool to the vehicle.
  2. Start the engine and allow the engine to idle.
  3. Using the scan tool, begin the automated bleed procedure.
  4. Follow the instructions on the scan tool to complete the automated bleed procedure. Apply the brake pedal when instructed by the scan tool.
  5. Turn the ignition OFF.
  6. Remove the scan tool from the vehicle.
  7. Fill the brake master cylinder reservoir to the maximum-fill level with Delco Supreme 11(R), GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
  8. Bleed the hydraulic brake system.
  9. With the ignition OFF, apply the brakes 3-5 times, or until the brake pedal becomes firm, in order to deplete the brake booster power reserve.
  10. Slowly depress and release the brake pedal. Observe the feel of the brake pedal.
  11. If the brake pedal feels spongy, repeat the automated bleeding procedure. If the brake pedal still feels spongy after repeating the automated bleeding procedure inspect the brake system for external leaks. Refer to Brake System External Leak Inspection.
  12. Turn the ignition key ON, with the engine OFF; check to see if the brake system warning lamp remains illuminated.
  13. If the brake system warning lamp remains illuminated, DO NOT allow the vehicle to be driven until it is diagnosed and repaired. Refer to Symptoms - Hydraulic Brakes.
  14. Drive the vehicle to exceed 13 km/h (8 mph) to allow ABS initialization to occur. Observe brake pedal feel.
  15. If the brake pedal feels spongy, repeat the automated bleeding procedure until a firm brake pedal is obtained.

 

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