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Old 24th February 2020, 21:28   #21
lionatus
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Each caliper corner bleeds as normal just NO pressure on pedal.

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Originally Posted by Alan_M View Post
What happens if you give the pedal a couple of quick pumps? Do you get a little resistance back?

What happens if you release a bleed nipple and push brake pedal down - do you get fluid being pushed out of the bleed nipple?
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Old 24th February 2020, 22:07   #22
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Never done all 4 at the same time. Always went in sequence rear/near to offside front. Would that help the whole circuit open?
I think at this stage it can do no harm, but with jars at the end of each nipple (obviously), if any of the jars do not expel fluid, then you know you have an issue with that line. You are at the stage where having some air in the system is the least of your worries.

I cannot understand how even if a seal flips in the cylinder, there would be no movement in the pedal.

Have you tried starting the engine?
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Old 24th February 2020, 22:18   #23
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[QUOTE=clf;2795252

I cannot understand how even if a seal flips in the cylinder, there would be no movement in the pedal.
?[/QUOTE]

My understanding of what is being reported is the pedal goes all the way to the floor with no resistance, I.e. no pressure being built up in the system when pedal pressed, so no braking. Or have I got wrong?
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Old 24th February 2020, 22:23   #24
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Each caliper corner bleeds as normal just NO pressure on pedal.
But what happens if you give the pedal a few quick pumps with all bleed screws closed?
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Old 24th February 2020, 23:36   #25
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It seems to me if you have no pressure at all in the pedal that we know exactly where the air is, it is in the master cylinder, right at the top of your system. It is going to take a lot of pumping and time to get it right from the top of your system to come out through a nipple at the bottom, and air likes to rise, not fall.

Are you absolutely sure the reservoir is being kept full throughout your bleed cycles?

Try pressing the pedal down and keeping it down for a while, while you let some fluid flow through one of the lines, just to make sure fluid definitely flows through from reservoir to the master cylinder. You must have an airlock somehow. It did happen to mine once. You need to get fluid flowing quite quickly for it to clear so either some furious pumping ensuring the reservoir is full at all times, or check for Jules post on the reverse bleed method and inject fluid through the nipples up-hill instead.

If using reverse bleeding, follow his guide to the letter not skipping any part of it.
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Old 25th February 2020, 11:01   #26
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From reading all of the above posts I can only conclude the master cylinder is not working. Even with a duff piston seal you WILL be able to bleed the brakes as there is no pressure involved. However under pressure the seal is not working.

With all the things you've done up to now it is very unlikely there is air in the system.---The piston seal in the master cylinder is dead.---


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Old 25th February 2020, 13:45   #27
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Quote:
Originally Posted by lionatus View Post
The pedal does move thats the problem. Theres no pressure. It goes straight to the floor with the blip my mate mentioned. I have no idea if he imagined it or not but slight pressure halfwayish then none suggests flipping seals to me. Be aware I was an IT professional not and engineering professional so my rationality is NOT based on experience only on educated guesswork. But several bleeds and no pressure still suggests air to me the 3 mechanics laughing at us are the ones saying master and seal flip. As we have no access to a T4 I have no way of knowing and even if MarinaBrian was willing thats a 65 mile drive with no brakes. I think I have TOAF somewhere does it have the ABS purge brakes thingy?
Either a fault with the master cylinder, (bear in mind though that if you didn't push the calipers' pistons back in whilst still connected to the car then there is no risk at all of flipping a seal.) or the level went too low when you were bleeding and you have entrapped air in the system.

How clean was everything? Any bit of muck getting into the system can prevent the seals from working if you are unlucky.

I'd have another go at bleeding it, as air entering the brake lines at the master cylinder will take some time to purge through.
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Old 25th February 2020, 16:48   #28
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Quote:
Originally Posted by lionatus View Post
we ran new brake pipes and bled all 4 sides succesfully but no pressure on pedal. My mate who was pumping the pedal for me whilest we bled the brakes said he thought he got a blip of pressure about 2/3rds of the pedal travel but no real pressure at all. Any ideas?
If you haven't already seen it, BigRuss's thread here might help.
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Old 27th February 2020, 22:10   #29
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Ok got it back on lift and spent 30+ mins back bleeding loads of air. Mickyboys master not needed so I have brakes. 2 pushes almost firm 3 and rock solid. Now I just have to get it back to the way it was and re-bleed normally to expel all air as the spongy brakes are back but at least I have them. Many thanks to ALL especially Jules who isn't in this thread but reverse bleed got the master clear enough to get operation back. Cheers, Guys. I can do the rest on the road outside the house with easy bleed until I get my brakes back to how I like them; instant response. On another not I've left messages with Brian aka MarinaBrian has he cut all ties? he's such a good guy unless someones ticked him off its not like him to not say anything? Cheers, Alan

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If you haven't already seen it, BigRuss's thread here might help.
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