BLEEDING THE BRAKES !! ??

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Arfron
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BLEEDING THE BRAKES !! ??

Post by Arfron »

I have renewed the brake lines ; put two new rear brake cylinders ; a new master cylinder ; and using silicone brake fluid . However , even using an Easybleed unit , I still cannot get the air out of the system ! When I press the pedal it requires one or two pumps to get the full hydraulic pressure . I have a small leak from a union connecting the rear wheel cylinder . I need to change the copper washer , I don't think that the leak is the main cause of my problem ? Also , is it normal to have a small spurt of hydraulic fluid squirting upwards from th m/cylinder reservoir , when you press the brake pedal ? ( when I say small , I mean about half a cm. at the most , or breaking the surface , nothing too dramatic ! ) Any suggestions on the correct bleeding process / tips would be greatly appreciated . Thanks :roll: Arfron
( Ps . Ihave just noticed the notes made on Page 2 by Cam / Chris ; however, how do you get the air out of the 'new' Lookheed M/cylinders etc ??)
rayofleamington
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Post by rayofleamington »

the master bleeds itself quite well. the small spurt is normal.

to bleed a complete system including wheel cylinders...
I would partly dissassemble the rear brakes, and press the pedal to push the pistons out - then push them back manually. This helps push the air out of the cylinders. (more important on the front ones though..)
but dont push the pistons out too far.
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Kevin
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Post by Kevin »

Any leak will tend to give a soft pedal as its letting air in, and when bleeding you start with the one furthest from the master cylinder and the final one of the 4 should be the nearest (you did bleed all 4 I suppose).
I have also heard that silicon fluid can sometimes be a so & so to bleed properly and I think that you need to have pressure on the pedal even before you open the 1st bleed nipple if there is a problem it becomes a two man job, I wonder if anyone else has heard or experenced this problem with silicon fluid.
Cheers

Kevin
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rayofleamington
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Post by rayofleamington »

generally silicon can be a disaster unless you replace all the seals.
Old seals that have sat in brake fluid for donkeys years do not always work with silicon fluid...

Even if you replace all the seals, silicon fluid is still more difficult.
Ray. MMOC#47368. Forum moderator.

Jan 06: The Minor SII Africa adventure: http://www.minor-detour.com
Oct 06: back from Dresden with my Trabant 601 Kombi
Jan 07: back from a month thru North Africa (via Timbuktu) in a S3 Landy
June 07 - back from Zwickau Trabi Treffen
Aug 07 & Aug 08 - back from the Lands End to Orkney in 71 pickup
Sept 2010 - finally gave up breaking down in a SII Landy...
where to break down next?
2013... managed to seize my 1275 just by driving it round the block :(
Arfron
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Thanks for the advice

Post by Arfron »

Thanks for the advice on bleeding the brakes ; clearly silicone brake fluid was a mistake in the first place . In fact, I have not used it before , but on readingh the advice given in various restoration manuals , I thought I'd give it a go. The only seals I haven't replaced are the front cylinders , so I assume that I should change these seals as well. If all this doesn't work can I revert to ordinary Dot brake fluid , without too many problems ? I must say that I have worked on variuos makes/ Lockheed / Girling and have not experienced so many inherent problems . Ah wel-- back to the drawing board !!
Thanks for your help very much appreciated :roll: Arfron
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