arry 0 Posted September 16, 2006 Help/advice please guys Recently I came round a bend to be presented with some dopy fool backing off his drive without even looking both ways Stuck the brakes on and, whilst it stopped me initially, the pedal sank to the floor and in the end there was no braking effort at all. No fluid loss at all - suspected master cylinder. Have now changed master cylinder for one that is allegedly only 2 years old, it certainly doesn't look old - I haven't bench bled it or anything but I'm assuming for now it's good. But I still have no brakes at all Turn the engine on and pump the pedal - it doesn't increase resistance in the pedal and there is a hiss from the servo. Turn the engine off and pump them it does get slightly more difficult to depress but still sinks to the floor and actually "clunks" on the way down the pedal range. Both ways, no braking efficiency. Disconnected the servo hose from the manifold - there's definitely vacuum there. Whilst servo is disconnected the effect on the brakes is as with the engine off, but there is still no braking efficiency. I have no fluid leaks I can see. The front callipers are only a couple of years old and I've replaced the rear cylinders within the last few months. Any help appreciated - I'm suspecting servo but don't want to go buying another one just to find out it's another waste of time and money On that note, does anyone know if the servos are the same throughout the range ie all servo assisted 205's/306's that sort of thing? Thanks all Arry Share this post Link to post Share on other sites
Guest rick03054 Posted September 16, 2006 (edited) If they've been fine since you changed the last component and there's no leaks I'd suspect the master cylinder. The servo only assists brakes. On the plus side new ones are only about £35 and you've had it off recently so shouldn't be too hard to swap Edit: I just re-read that, did you swap the MC after the brakes stopped working? If so did you bleed it really well? Edited September 16, 2006 by rick03054 Share this post Link to post Share on other sites
welshpug 1,627 Posted September 16, 2006 you havent bled the brakes what are you like DONT UNDER ANY CIRCUMSTANCES DRIVE IT ANYWHERE BEFOPRE BLEEDING THE BRAKES hop i've got my point accross, have you checked the pads? and also the operation of the self adjust mechanism in the rear drums? Share this post Link to post Share on other sites
arry 0 Posted September 16, 2006 That's the thing though, I've just swapped the master cyl and I'm kinda sceptical that I've got 2 identically screwed master cyls Share this post Link to post Share on other sites
welshpug 1,627 Posted September 16, 2006 BLEEED THE BRAKES Share this post Link to post Share on other sites
arry 0 Posted September 16, 2006 Heh, I have bled the brakes And I've not driven it anywhere, there's not much point - if the brakes don't work at a standstill I'm fairly sure they won't when the car's moving I've not checked the pads - what could go wrong with them to the extent that I have no effort at all at the pedal? Similar question re self adjusters on the drum? I have had the drums off to change the cylinders but this was some time ago, and I made sure I adjusted the shoes up to specification as well as correcting the handbrake assembly which had been bodged by the previous owner. This is going back a few months now. I'm confused Share this post Link to post Share on other sites
Guest rick03054 Posted September 16, 2006 I thought by bench bled you meant some kind of off the car test. Going mainly on the fact that you say you swapped the calipers and you must have used them in that time, and your still here! Assuming you have bled the brakes, did you pump the pedal right down to the floor with bleed nipples open? I've been told that can pop the seals because they go further than they're used to. Share this post Link to post Share on other sites
arry 0 Posted September 16, 2006 I thought by bench bled you meant some kind of off the car test. Going mainly on the fact that you say you swapped the calipers and you must have used them in that time, and your still here! Assuming you have bled the brakes, did you pump the pedal right down to the floor with bleed nipples open? I've been told that can pop the seals because they go further than they're used to. No the callipers were swapped some time ago by the previous owner. When I got the car I took it for MOT and found that the rears weren't working so well, turns out the previous owner wasn't quite the capable mechanic he should have been for such a job as changing the rear shoes as he'd stuck various bits back in the wrong place and the handbrake adjuster latch thingy was floating around in the drum Changed the rear cyls and one corroded brake line - bled it all up - lovely, full working brakes. Then, about 2 months on (which is last week or so) the brakes failed. My gut instinct was BMC which I've now changed and tried to bleed the brakes up, but when pumping them there's still very little effort and if you turn the engine on it just goes super easy to depress to the floor. Admittedly there is still some air in the system as I could do with going back round again but I'd expect the pedal to be getting stiffer by now and it's just clearly not doing that at all Share this post Link to post Share on other sites
Guest rick03054 Posted September 16, 2006 I've just replaced the rears on my car and the pedal didn't go stiff until I got ALL the air out. Try going round again bleeding them excessively, making sure the reservior is topped up all the time. See if that helps. Out of curiosity what method do you use to bleed them? as per haynes? one man or two? Share this post Link to post Share on other sites
arry 0 Posted September 16, 2006 two man - I have got a vacuum bleeder in the workshop but it's an arse to use IMO and I had a spannermonkey mate handy. I'll give it another go tomorrow - hopefully it'll come up! On a side note, does the BMC seal the vacuum chamber of the servo? Share this post Link to post Share on other sites
Guest rick03054 Posted September 16, 2006 two man - I have got a vacuum bleeder in the workshop but it's an arse to use IMO and I had a spannermonkey mate handy. I find that the best too, I prefer to do the caliper end so I know no air has got back in, just a thought. I'll give it another go tomorrow - hopefully it'll come up! Get your spanner and go back out there you pu**y, I want to know if it helps On a side note, does the BMC seal the vacuum chamber of the servo? Not as far as I know, I'm sure I've seen someone who fitted a Gti-6 engine space out one side of the MC so it doesn't hit the belt cover. Share this post Link to post Share on other sites
hengti 2 Posted September 16, 2006 bleed the brakes, obviously be careful with the m/c you've put in though - if you've been pumping the pedal up and down with no fluid in the m/c, there's apparently a danger that might have inverted the seals in the m/c which could lead to later failure i don't understand why people fit s/hand m/cs - they're only £30-£40 new and are *safety*critical*!! i'd only ever fit a new one Share this post Link to post Share on other sites
arry 0 Posted September 16, 2006 Get your spanner and go back out there you pu**y, I want to know if it helps Haha, I would - but it's over at the workshop and I can't be assed to walk over there again tonight Not as far as I know, I'm sure I've seen someone who fitted a Gti-6 engine space out one side of the MC so it doesn't hit the belt cover. Now that's a cat amongst pigeons - as when I took the nuts off it, it started to hiss at me i don't understand why people fit s/hand m/cs - they're only £30-£40 new and are *safety*critical*!!i'd only ever fit a new one To be fair the best quote I got for one from the various local motorfactors around here was £58, and the one I bought was only 2 years old and cost me a tenner. I'm usually of the same opinion but let's face it, the original master cyl on this car has done 154k, if I bought a new one now I think several other components would be in need of replacement before the MC failed again Share this post Link to post Share on other sites
arry 0 Posted September 17, 2006 Hmm, well, weird one. Tried to bleed the brakes via pumping the footbrake but there wasn't any hydraulic effort, none, nothing! No fluid coming out of nipples. Took the BMC back off, cleaned the mating faces up and refitted using some grease as a seal. Refilled and bled the brakes through again and now I have mechanical effort again - used the vacuum bleeder to pull most of the air through and then went round a couple of times in the correct bleeding order. Now have brakes but they're still not as good as they used to be. Have bled them twice through but I'll do a third time when I can clear the workshop out again just to make sure. Not entirely sure what happened first time round on the BMC fitting - I can only assume that it does indeed form part of the servo vacuum chamber seal but, since I'm not sure how the BMC is actuated, I'm not sure what effect it would have if this seal wasn't perfect. Anyways - solved for now, sort of! Thanks for your help Share this post Link to post Share on other sites
Guest BrainFluid Posted September 17, 2006 Just thought I'ld add this, For a quick test if you suspect there IS air in the system,... Put a clamp over the rubber hoses at the back and give the pedal a try. If the pedal stiffens up at all then theres air still in the system. Nate. Share this post Link to post Share on other sites
Guest rick03054 Posted September 17, 2006 Just thought I'ld add this, For a quick test if you suspect there IS air in the system,... Put a clamp over the rubber hoses at the back and give the pedal a try. If the pedal stiffens up at all then theres air still in the system. Nate. That would only work if there was air to the rear of the clamp. If there is air anywhere else in the system it will still compress and give the spongy pedal feel. I'm pretty certain the MC doesn't need a seal, however that's irrelevant, the end result is that the rod inside it pushes on the MC, which pushes the piston/s out and pushes on the brake fluid. Some cars work with no servo at all so you should still get some effect, the same as you would with the engine off. If there are 100% no leaks, the pads are ok (aren't they?), you've kept it topped up with fluid and you've bled it properly, it should work. However sods law dictates otherwise Check and check again, however to be honest I would suspect the MC. Good luck Share this post Link to post Share on other sites
arry 0 Posted September 18, 2006 Pads and discs up front are pretty new, as are rear shoes. 100% no leaks. Topped up with fluid and bled through properly. Like I say, I'll bleed em again when I've got the workshop floor back Cheers for the help Share this post Link to post Share on other sites
