Constant air in line while bleeding

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  #1  
Old 03-23-10, 07:25 PM
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Constant air in line while bleeding

So I am trying to bleed the brakes on a 1992 Chevy Corsica for a friend. Constantly while I try to bleed the air out, there is a swoosh of lots of small bubbles, and some large bubbles following it/between the smaller bubbles. It doesn't go away or change.

I have a friend push the brake pedal, and while it is pushed, I momentarily open the bleed screw with clear line, and let it drain, then shut the bleed screw while he lets the pedal back up.

This is also a brand new master cylinder has been installed. I did my best to bench bleed it, but they didn't provide every fitting that was required to do so, and so while I felt I did an OK job, I believe there were still small bubbles remaining.

I also tried bleeding the two upper bleeder screws on the master cylinder, and managed to get just one tiny bubble after many pumps.

I just don't know what to do. I wonder if I should get another master cylinder? What else could be wrong?
 
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Old 03-23-10, 07:31 PM
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Does the vehicle have anti-lock brakes?
 
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Old 03-23-10, 07:34 PM
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Originally Posted by Bill190 View Post
Does the vehicle have anti-lock brakes?
Yes, it does.

The reason why I replaced the master cylinder is because the brakes failed suddenly.

I have to mention, while the pedal is pushed down, there is an awful squeaking sound from the front of the car during the last few inches of travel of the brake pedal.
 
  #4  
Old 03-23-10, 07:44 PM
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Well there are *exact* procedures for bleeding a brake system with ABS. This would be outlined in the factory service manual set of books you can order from helminc.com for about $150.

And there may be special tools required to open valves. And the ABS pump motor would need to by cycled by a scan tool.

Here is a sample of what is involved...
Bleeding ABS Brake Systems
 
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Old 03-23-10, 09:42 PM
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Originally Posted by Bill190 View Post
Well there are *exact* procedures for bleeding a brake system with ABS. This would be outlined in the factory service manual set of books you can order from helminc.com for about $150.

And there may be special tools required to open valves. And the ABS pump motor would need to by cycled by a scan tool.

Here is a sample of what is involved...
Bleeding ABS Brake Systems
None of those systems looks like what I have. The master cylinder is bolted directly to the ABS modulator.
 
  #6  
Old 03-23-10, 11:54 PM
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Here is GM procedure for that one Wolf. I included only the manual methods along with the manual bleeding. You must have the master bled out before starting this.Good Luck
Notes

Before bleeding the rear brakes, the rear displacement cylinder pistons must be returned to their top most position. Using a TECH 1 scan tool or suitable equivalent, enter the manual control function and ``APPLY'' the rear motor. Ensure the enable relay is ``ON.'' If a scan tool is not available, bleed the front brakes to ensure that a firm brake pedal exists, then carefully drive vehicle over 4 mph to cause the ABS to initialize itself. This will return the rear displacement cylinder to the top position. The entire brake system should now be rebled.

Manual Bleeding

1. Remove master cylinder reservoir cover, then fill reservoir as necessary.
2. Attach one end of a clear plastic hose to rear bleeder valve of the brake control assembly, then put opposite end of the hose into a clean container of brake fluid.
3. While depressing brake pedal, slowly open bleeder valve, until fluid begins to flow.
4. Close valve and release brake pedal, then repeat procedure for front bleeder valve.
5. Ensure master cylinder is full, then raise and support vehicle.
6. Bleed wheel cylinders and calipers using the following sequence:

1. Right rear.
2. Left rear.
3. Right front.
4. Left front.

7. Lower vehicle and check fluid level in reservoir, fill as necessary.
8. Turn on ignition and note pedal travel and feel as follows:

1. If pedal feels firm and constant, start the engine and recheck pedal travel, if pedal still feels firm and constant, proceed to step 9.
2. If pedal feels soft or has excessive travel either initially or after engine is started, repeat bleeding procedure.

9. Road test vehicle, make several normal stops from a moderate speed, then make one or two ABS stops at approximately 50 mph.
10. Ensure pedal is still firm and constant.
Make sure your dealing with a 92 also the 93 has a different set of steps
 
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