mistergrumpy
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| posted on 23/3/09 at 07:39 PM |
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Brake Bleeding
Jeez, this subject seems to get raised about once every month but here goes. I'm after a bit of reassurance here I think as I think what
I'm doing is right. I've bled brakes before loads of times but not encountered the problem I have now.
I've replaced my master cylinder and put a bias valve in the rear line. I've gone to bleed the brakes today and nothing's coming out
of the nipples except for one. When I opened this nipple I heard it suck or blow air. Anyhow, connected the one way valve thing on that I always use
and got my brother to start with the pedal. The fluid started slowly moving very slowly backwards and forwards towards the end and I'm now
getting some medium bubbles and lots of tiny ones but I've gone through maybe 500ml of fluid and not getting anywhere quick and still
there's nothing at all on any of the other nipples.
Is there just hods of air in the system and I've got to work it through? Never had it take this long before and always had fluid at the nipples
when I tried them.
I've trapped the pedal closed overnight to see if that helps.
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flak monkey
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| posted on 23/3/09 at 07:57 PM |
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Take the caliper off the rear (assuming you have discs!) and for a start hold it below the level of the m/c and let gravity help some of the fluid
through. Then hold it well above the master cylinder and proceed to bleed it in he usual way..
This methods worked well for me before when bleeding troublesome brakes.
Always remember to stick something in the caliper though to stop the pistons popping out!
The other way is with the good ol eezibleed. If brake fluid helps along by 30psi isnt getting through then you have another problem.
Also is your bias valve completely open?
David
Sera
http://www.motosera.com
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BenB
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| posted on 23/3/09 at 08:06 PM |
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I'd also recommend the Eezi bleed. I usually use that for initially filling the system and for fluid changes after that I just use a one way
valve type thingy from Halfrauds.
Even with the Eezi bleed it took me a good litre of brake fluid to get my brakes sorted.
Top tip- Halfords DOT4 1L = £7-8, 5L = £13
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mistergrumpy
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| posted on 23/3/09 at 08:14 PM |
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Cheers fellas. I'm just not trying hard enough then I think. Top tip with removing the caliper cheers.
Fluid's loads cheaper at Brakes International so I'll try that if I'm going to use much more. I've always had them sorted in
less than a litre you see.
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nitram38
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| posted on 23/3/09 at 08:40 PM |
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Make sure you don't have a leak somewhere hidden.
You will never bleed them if you have.
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britishtrident
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| posted on 26/3/09 at 08:07 AM |
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Sounds like the piston in the master cylinder isn't coming fully back -- most likely cause is the pedal push rod or pedal stop is needing
adjusted -- ie shortened.
The piston in the master cylinder needs to come full back against the stop washer/circlip or fluid can't flow from the resevoir into the
system.
A good tip when fitting a new master cylinder is to put bleed nipples in all the outlets and prime/bleed the cylindr on the bench before fitting,
then when you fit it to the car only a minimum ammouts of bleeding is required.
[Edited on 26/3/09 by britishtrident]
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mistergrumpy
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| posted on 26/3/09 at 05:30 PM |
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I've already shortened the pushrod as short as it can feasibly go without fouling. I left the brake pedal wedged for a couple of days and I
bought an Eezi bleed earlier.
I managed to bleed them though they were a bit slow, particularly the backs. The pedal isn't great. It floored a couple of times but this was
corrected by just pulling the pedal back a touch. I'm managing to get one wheel locking now but I suspect there's still air in the system
somewhere so I'm going to jam the pedal in again tonight and try again tomorrow.
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rusty nuts
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| posted on 26/3/09 at 06:56 PM |
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Jamming the pedal down will not remove air from the system !IIRC what it does is to compress the bubble and make it smaller but it is still in the
brake line.
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mistergrumpy
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| posted on 26/3/09 at 07:01 PM |
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Yes that what it seems to do. Just makes it a bit easier when bleeding that one big bubble comes out instead of trying to work a load of little ones
through.
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goaty
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| posted on 26/3/09 at 07:33 PM |
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i find the one way valves are only good once you have fluid to it, not just air.
Again as above, Ezzi bleed is the nuts, still took me ages to get the rears bled right. Taking them off make a big diff on mine too.
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mistergrumpy
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| posted on 26/3/09 at 07:43 PM |
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The problem with the eezi bleed i found is that when you've finished there's too much fluid left in the MC and I had to start trying to
drain it.
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rusty nuts
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| posted on 27/3/09 at 07:08 PM |
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Kitchen baster thingy works a treat , or one of those ink refill syringes Use a new one though , you don't want to contaminate your new fluid
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mistergrumpy
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| posted on 27/3/09 at 07:12 PM |
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Oh! You know what I forgot? I've a few syringes in the tool box that I forgot about. Bugger. Cheers for the reminder Rusty.
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goaty
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| posted on 28/3/09 at 06:52 PM |
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keep one in my bleed kit 
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