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Brake bleeding

Posted: Fri May 13, 2011 1:40 pm
by dfyates
I really do wonder if this is a new topic!! Renewed recently all brake pipes and cylinders. Despite man-and-wife bleeding and also an automatic thing with a non-return valve, the pedal still has virtually no resistance. Master cylinder seals were replaced also.
Do I really have to resort to pressure bleeding?

Re: Brake bleeding

Posted: Fri May 13, 2011 2:35 pm
by bmcecosse
No! First step - have you adjusted all the brakes up HARD against the drums? Then - can you pump up pressure in trhe system? If not - perhaps there is a problem with the seals in the master. If you can pump pressure - do that and then release the furthest away nipple briefly - quick open/close movement. pump up pressure again and repeat a couple of times. then move to the next nipple etc etc until you get a good solid pedal. Then release the brakes off the drums - so they are 'just' rubbing and all should be well. :)

Re: Brake bleeding

Posted: Fri May 13, 2011 6:17 pm
by MarkyB
Seconded, also is there still air coming out of all the cylinders?
If there is get a new master cylinder.

Re: Brake bleeding

Posted: Fri May 13, 2011 8:21 pm
by dfyates
bmcecosse wrote:No! First step - have you adjusted all the brakes up HARD against the drums? Then - can you pump up pressure in trhe system? If not - perhaps there is a problem with the seals in the master. If you can pump pressure - do that and then release the furthest away nipple briefly - quick open/close movement. pump up pressure again and repeat a couple of times. then move to the next nipple etc etc until you get a good solid pedal. Then release the brakes off the drums - so they are 'just' rubbing and all should be well. :)
Yes, that's what I meant by bleeding the brakes, done that.....

Re: Brake bleeding

Posted: Fri May 13, 2011 8:23 pm
by dfyates
MarkyB wrote:Seconded, also is there still air coming out of all the cylinders?
If there is get a new master cylinder.
Cylinder has been replaced as stated. No air exiting from bleed screws.

Re: Brake bleeding

Posted: Sat May 14, 2011 9:45 am
by chickenjohn
Make sure all brake pipe unions are tight as well. if you've recently replaced part of the brake pipes, check for tightness.

Re: Brake bleeding

Posted: Sat May 14, 2011 2:24 pm
by Neil MG
You don't have disc brakes do you? If so the bleed nipples must be at the top otherwise you cannot bleed the system.

The non return valve bleeders can often fail to bleed properly if air is drawn up the thread of the nipple. Recheck that the pads are tight, they need to be able to move freely in their slides or they can stick and appear tight (locking the drum) when in fact they still allow the cylinder to move. Go around again after pumping up the pedal and tighten them all as tight as you can. Then bleed the brakes again with an assistant. You possibly just need to put more fluid through.

Re: Brake bleeding

Posted: Sat May 14, 2011 3:23 pm
by xpress
Leave the top off the cap and wedge brake pedal with something overnight. Don't over tighten nipplest just nip them up no more then check resistance when putting load on them. Bleed all round day 2 with one way valve. Put another 500 ml through and report back. Don't reuse old fluid! Good luck!

Re: Brake bleeding

Posted: Tue May 17, 2011 10:43 am
by Rob_Jennings
get one of these easy bleed rubber tube things

http://cgi.ebay.co.uk/SOLO-BRAKE-CLUTCH ... 2ea57e4fdc

simply pop over the brake bleed nipple, loosen off, pump the pedal a few times (quick down slow up), tighten up and work your way round the car.

best couple of quid I ever spent, always worked well for me even when the garage had trouble getting air out of the system. I'll never go back to working in pairs and the up-down method !!