I was thinking about the proportioning valve as well but cant seem to find anyone that sell them.
Plus was told my MC was new and found it was a rebuilt so switchibg that out tomorrow with a new one plus the new MC is cheaper but $10.
Looking closely at your bleeding procedure. That could be the problem - unless I'm not reading this right:
Up closed bleeder down opened bleeder.
You don't want to allow the pedal to return to the top with the bleeder open.
As the brake pedal rises, the piston in the MC retracts. This creates a negative pressure in the system and induces a backflow of brake fluid in the lines.
When the bleeder is opened and the brakes are fully applied, air is purged (along with some amount of brake fluid).
But if the pedal is released
with the bleeder still open, any air that was successfully bled out will be drawn back in - plus some more air equal to the amount of brake fluid that came out with it.
Be sure that the bleeder is closed before allowing the pedal to rise. Here is GM's bleeding procedure:
- Bleed right rear brake as follows:
- Depress brake pedal slowly one time and hold.
- Loosen bleeder valve to purge air from brake, then tighten bleeder valve and slowly release pedal.
- Wait 15 seconds, then repeat sequence, including 15 second wait, until all air is purged.
- Bleed left rear, right front, and left front brakes, in that order, using same method as for right rear brake.
- Check brake operation and ensure pedal is firm. Also check master cylinder fluid level and add fluid as necessary.
