Bleedin brakes!, literally.

[currylager]

Hello All,

Yet another weekend of lying on my back in the cold, close but no cigar. New brake pipes, hoses, callipers, rear cylinders, 3 litres of fluid later and i still have an extremely spongy pedal, if worth calling a pedal at all?. There apprears to be air coming out in the bleed tube even now :twisted: . The question is, is it possible the master cylinder fooked? or what else should i try, getting earache off the missus because i stink of brake fluid, not Hugo Boss lol? heeeeeeelp!!!

 

[cyberdyne systems]

Always start with the cylinder furthest away and work your way nearer, are you saying when the brake pedal is pushed down you still have air coming out despite flushing that much fluid through?

Make sure you dont let it get to low in the reservoir otherwise it will pull air in too, and use a one man bleed kit or tighten the bleed nipple when the pedal is allowed to come up so it doesnt draw air back in that way.

If the master cylinder is at fault its not such much a spongy feel, rather it will go down too far and then sometimes be normal.

 

[VWAIRCOOLED]

What was the original problem with the brakes? Did you have a solid pedal before you started? Starting the bleeding from the rear is the best as cyberdyne systems said.It looks to me like you could have a severe pressure loss somewhere in the system (a hole in a pipe or a loose connection) Or the master cylinder isn't pumping any fluid.Check the master cylinder first,loosen the unions off where the pipes lead to the brakes,fill the reservoir and get someone to pump the pedal,if that fails to provide any fluid then either the master is f.u.b.a.r or fluid isn't able to get into the master cylinder because there maybe a blockage in one of the reservoirs or the pipe connecting the two.If you can see fluid in the lower reservoir by shining a light through it and shaking it gently,it should be ok there.See how that works out.

 

[currylager]

Thanks for the replies, the problems are with my friends bus, i agreed to help him lower it this winter via red 9 and we have encountered numerous problems including rotten front beam, rotten chassis in places, missing/ rotten rear chassis suspension mounts, knackered front callipers, rotten front brake pipes, shagged brake hoses, rotten rear brake back plates, knackered rear brake cylinders, contaminated/ knackered rear brake linings, knackered rear brake drums and more .

Any how after a new front beam, lots of fabricating/ welding, new front pipes, hoses, calipers, pads, new back plates, cylinders, linings, drums, take a big breath....... and after 5 saturdays on our backs we are now on the home straight with only the brakes to bleed and adjust :mrgreen:

There are no visible leaks to the system and i started at the furthest point working backwards, even bleeding the brake compensator unit under the front of the bus, but we are still getting minute air bubbles in the fluid :evil: . On the first stroke the pedal hits the floor and if you pump it it will become harder, which points to a masiive air lock, but where?, i tried to use an easy bleed kit but when you pressurise it, it just blows the cap of the top off the reservoir bottle covering the floor in brake fluid :twisted: . At 15-30 yesterday we threw in the towel and decided we need to go back to it next weekend with a fresh approach, or maybe a new master cylinder, so i decided i'd call on you guys for some support and see if there was anything else i could try :roll: . I think we will definatly be buying a gallon can of brake fluid before we retry :roll:

My bus is coming back from the paint shop at the end of Feb so i'd really like to get my mates bus finished so i can concentrate on the unenviable task of fitting all new window seals to mine :wink: .

Best regards,

James

 

[ground hugger]

Have you put the calipers on the right way round bleed nipples up.
Its been done before and no doubt it will be done again :|

 

[Loxy]

how old is the master cylinder? might not hurt to replace it seeing as you have replaced pretty much everything else?

Doesnt the easibleed screw on to the reservoir? is the cap the wrong size?

 

[froggy]

Try narrowing down where the fault is. i now most people will slate this but,
Using some mole grips clamp ALL the rubber brake lines to the 4 wheels and try the pedal, is it hard? If so then you know the master cylinder and all associated lines are good, if not master cylinder faulty?
If the pedal is hard then remove 1 clamp at a time trying the pedal between each removal until the pedal goes soft, clamp this 1 back up then try all the rest, if the pedal is firm then the problem is something to do with the associated wheel.
When i had a problem with mine we tried this and it turns out that the caliper i had was un-side down as the bleed nipple at the bottom
Not saying it will work for you but it did for me :wink:

Also (not teaching you to suck eggs) but pump the pedal until its firm before opening the bleed nipple, close the bleed nipple and repeat, do this a few times on each corner starting at the back.

 

[currylager]

Thanks for the advice, some very useful info there, i will check to ensure i havent got the calipers upside down, i assume its possible to have them on the wrong sides perhaps, i promise i will own up if this is the case :wink: . I have also bought another type of bleeding kit which sucks the fluid from the bleed nipple, so i'll give that a go too. I can now see there is scope for improvement and i now have some ideas to work on after losing my direction. Thanks a lot.

James.

 

[froggy]

I should be around next weekend if you need any encouragement!
Let me know

 

[currylager]

I should be around next weekend if you need any encouragement!
Let me know

Thanks a lot for the offer, unfortunately my friend is away next weekend, so i wont know until the following week whether the problem can be resolved. This is frustrating because things are progressing in the paint shop and i reckon the next time i see my bus it will be in its topcoat, then i'll be really busy :wink: