Air in brake system - no idea where from

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Edmard
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Air in brake system - no idea where from

Post by Edmard » 04/10/15 14:07

Afternoon all, in a bit of a pickle with the brakes on my AW11 (Mk1b).
Yesterday I rebuilt both the rear calipers because they were completely perished and had worn down the pads and warped a disk as a result. So they have been rebuilt and I put new disks and pads on all round.
I thought while I was at it I would bleed the brakes because why not? God knows when they were last bled.

But now I have put almost a litre of fluid through and the pedal still feels mega spongy and I can push it nearly to the floor after pumping. Also with everything nice and tight I push the brake pedal and i can hear bubbles in the system and I can see them coming up into the master cylinder.

So I have no idea what the issue is. I was even using a one way valve when I was bleeding them! And on top of that closing the nipple as the brake pedal comes back up after bleeding. No idea where this air is coming from.




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Re: Air in brake system - no idea where from

Post by notroubleclubber » 04/10/15 14:12

I'd get 2 people to bleed them.
I've never trusted those one way valves.

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jimi
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Re: Air in brake system - no idea where from

Post by jimi » 04/10/15 18:48

Edmard wrote:And on top of that closing the nipple as the brake pedal comes back up after bleeding. No idea where this air is coming from.
You should be closing the nipple before releasing the pedal not as the pedal comes up, if your check valve (one way) isn't sealing properly then you'll be drawing air back in.
If your seeing bubbles in the reservoir then I'd be very suspicious of the master cylinder, it's extremely unlikely that any air in the system at the brake cylinders could make it's way to the reservoir.
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