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Usually a hard brake pedal is the brake booster. Since you replaced that it is out f the picture (unless the replacement was bad). This issue of the pedal going to the floor is troublesome and potentially dangerous. If it is not doing it all the time, it probably soon will. What most likely occurred, and this happens quite often, is that after having had the hoses and calipers replaced, it was necessary to bleed the brake system of air in order to get proper brake operation. This requires depressing the brake pedal numerous times to the floor while purging air from the system. There is a potential problem in this and that problem is that the o-rings in the master cylinder can be damaged by the bleeding process, because the normal stroke of the master cylinder is much shorter than the one used during bleeding. This sometimes results in o-ring damage because the master cylinder bore may have worn a ridge in it where the normal stroke ends. The repeated passing of the o-rings over the ridge will damage them and can cause them to fail. When this happens the pedal will drop to the floor. You really can't blame the mechanic for this but it most likely happened as a result of the work done. Have the master cylinder replaced ASAP. I wouldn't recommend using the vehicle at all in the meantime.. it is a pedal-press away form total brake failure at any given moment.
once should have been enough to get it fixed
indicates a master cylinder failure
go to a brake specialist shop for a proper diagnosis and quote
the master is probably original and is well past a replacement maintenance period
may i suggest your problem is the brake master cylinder is faulty ie the line pressure is being lost due to fault on seal that is supposed to maintain brake pipes/line pressure when pedal is off resulting in brake pedal intermittantly going to floor but if you pump pedal it comes back ? the fact you mention you drained master cyl ? reservoir ?? and fluid was dirty ? assume you bled all brakes to flush b/system too ? the fluid being dirty is a clear indication that the seals on m/cyl pistons are deteriated and allowing fluid to pass seals and cause pedal to travel further SO best advice is to replace the master cyl as repair kits/seals are hard to come by these days then use new fluid and bleed all brakes/cyl's hope this helps ?
double check fluid.you have air or are losing hydrolic pressure somewhere. leak in master cylinder can do this. also vacume and air leak in the booster unit. double check bleading points on each wheel.
don't know about the rear brakes, but it is the brakes!!! You are out of fluid, might have a leak, get the reservoir filled up, and check all the wheels on the inside for brake fluid leaking. If the pedal has gone to the floor, you will need to bleed the system, Just get 2 people, one to loosen the bleeder on each wheel, and one to pump the pedal, Get a short hose and a can to catch the oil in. Loosen the bleeder screw, let the pedal go down, don't remove pressure till you tighten the screw back up, pump it up again, and do it till the pedal comes back to normal. Every wheel.
The problem may be that the master cylinder needs to be bench bled,there is most likely air trapped in the piston of the master cylinder.The problem comes from the piston not being fully actuated when connected to the pedal assembly.A vacuum bleeder will generally pull it out.
Well this is very serious I hope you deal with it right away. You mentioned that sometimes the pedal was hard,do you mean that its all the way up and it doesnt feel like you have power brakes?? If so have you noticed any sounds like air escaping (swoosh sound when brakes applied)? Failure of the power booster causes pedal to become very hard and could possibly be your problem for hard pedal if I understood you correctly. check to make sure that vacuum to the booster is conected properly and hose not kinked..Now for the solution for the pedal fading to the floor... You either have air in your brake system, A bypassing master cylinder , or a hydraulic leak...Were your brakes serviced recently?? if so try bleeding your brake system first...That would be the first step if still the problem persist I would isolate exactly where the problem was coming from.. To do this you would start at the passenger rear wheel and line clamp the brake hose to make that part of your brake sytem inoperable...when clamped try your brakes and note if brakes improved or had know affect on system (when testing obviously im not suggesting you drive to determine results of test procedure)repeat test for each wheel you have isolated the problem when brakes feel normal with one wheel clamped,which ever it may be.. This isnt as hard as it might soun and if you are confused at all dont hesitate to ask questions... Remember the only dumb question is the one you fail to ask I would hate for you to get into an accident ... Good luck!!!