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I was taught to bench bleed master cylinders as an apprentice but I haven't used it in 40 years. I find it unnecessarily messy and wasteful and distinctly unhelpful. The only thing it has some use for is testing a master cylinder that has just been rebuilt.
I fit the master cylinder dry and connect the pipes regardless of how many ports it has. At this stage my colleague prefers to use a vacuum bleeder but I use an assistant to press and hold/release the brake pedal on command as I release and tighten each pipe in turn with lots of cloth to catch the spillage.
Once I am satisfied the master cylinder is pumping effectively I bleed the system at each wheel as usual.
Car manufacturers don't bench bleed master cylinders. They bleed hydraulic systems by gravity and that is still the best way to fill a system in the repair shop.
Did air get into the master cylinder? If you can, try bleeding the master cylinder. The fact that you aren't getting any fluid out of the line suggests that the master cylinder isn't pumping fluid.
Master cylinders are (usually) on a split circuit system - that is, the front left brake is on the same line as the rear right. The front right brake is on the same circuit as the rear left.
A point to be aware of is when bleeding brakes/doing brake work and if the master cylinder runs dry, is that a seal inside the master cylinder can fail/twist over and not pressurise that particular line, even though it may pressurise the opposite brake line.
I'm in the UK. I have a 1998 Jeep Grand Cherokee 4 litre, which I am slowly rebuilding. Three weeks ago I fitted new front brake rotors, new front callipers and pads. I've been rebuilding cars for over 40 years now and have done countless brake overhauls.
.. and could I get a hard pedal after the job was completed? I must have bled the brakes three times a day for a week and couldn't get a brake pedal. I phoned a full time mechanic I know - he came and tried to bleed the brakes three times and couldn't get a hard pedal.
That's when you think 'The master cylinder was working before I started the job so it must be still working now'.
I fitted a brand new master cylinder and because some parts for older jeeps are hard to come by in the UK, I fitted a second hand proportioning valve. When I bled the brakes again the pedal became rock solid. Fixed.
You're probably fed up with your braking problem now ... and apparently this 'no fluid/brake pedal' is more common than you may think.
Try bleeding the master cylinder if you can. If you suspect that it isn't fully working - try an overhaul kit which is cheaper than a new master cylinder.
As for changing the proportioning valve .. that's your decision. My brakes now work though the truth is I don't actually know which was at fault as I changed both the master cylinder and proportioning valve at the same time. Maybe both were at fault, for whatever reason. I genuinely don't know.
The positive aspect is that you are doing your own work and know what you're doing. You're saving on labour charges.
Your clutch fluid reservoir may need brake fluid-yes, it uses brake fluid as a hydraulic fluid. Check reservoir on the firewall. It will sit beside the brake master cylinder. The reservoir sits atop the clutch master cylinder. If it was dry, the clutch may need bleeding down at the slave cylinder on the transmission housing-where the clutch fork sticks out of the transaxle.. Open the bleed valve on the slave cylinder, and have someone slowly press clutch down. Keep bleeding until a steady stream of fluid comes out when clutch is pressed. Then close bleed valve, check clutch operation-pedal should have some pressure on it now.
Sounds like the master cylinder is full of air.Somebody let it run dry when doing a pad change.(maybe)Did the calipers get rebuilt or were the pistons just pushed back in?
Brakes are a sealed unit.If there is no leaks,then you must start at the 1st point of operation.The master system.Hope this helps.
Yes, try bleeding the brakes again, you may have to bleed the front brakes too. when the master cylinder goes dry from a broken line sometime air gets into the front lines also. otherwise the master cylinder could be bad when the pedal goes past it normal travel sometime it tears the seals inside and you be unable to build pressure in the master cylinder
Need to have it check could be clutch master cylinder or slave cylinder or hose from clutch master cylinder to slave cylinder.check brake fluid at clutch master cylinder sit next to brake master cylinder if empty could have a leak. fill and pump peddle and look for leak.
YOUR problem is that your clutch is nodoubt out of fluid and the pedal has gone to the floor so the answer should be either find the fluid leak first ,,then open the master cylinder and refill and bleed the clutch by pumping 4 times fast ,hold down undo nipple on slave cylinder and then do up repeat 4 or 5 times and it should be ok IF not then the master cylinder is faulty replace it or get it rebuilt...
Let me know how you get on with it ... Ron
There is Supposed to be a Gasket Between the Booster and Master Cylinder. If this Gasket is Gone it will leak like this. If it is Still There, You may need a New Master Cylinder or Booster Depending on what you find when you get it Opened up. Please Rate My Response! Thanks!