No brakes peddle just goes to floor. Cannot get the master cylinders to make pressure. Been having issues for years, having to pump up one side, and the other not feeling 100 percent. original ones being old were first suspect. I ordered some chinesium replacements. No fix. Odd two bad masters but stranger things have happened. Ordered some supposedly better replacements. No fix. We have checked. Reservoir for blockage. pulled a bleeder to check for blockage. pulled a line loose (to isolate from master to bleed) Adjusted the rods to max stroke. So that is supposedly six bad master cylinders. They will not make pressure. Completely out of ideas.
What are you using for brake fluid ? Case TCH or it's equivalent is what is required. Never use DOT brake fluid.
Hy-tran plus
Perfect ! Do the master cylinders stay full of oil ? If you pump the pedals repeatedly do you get any braking action at all ? Worn out brake disks ?
We pulled the hard line from the rubber hose line on top of transaxle, checked hard line for pressure. there is no pressure. Very little fluid movement. The peddles have no resistance. reservoir fluid level remaining constant. Good idea. Will check for fluid on both sides of pistons. The other set of master did the same thing. We even vacuumed fluid to bleeders for them.
Do you have the service manual for your 580K ?
Yes. tried the power bleed procedure, Last time. Does not seem to be applicable to this issue. Another good idea. Will try reading thru the sections again.
Make sure you are getting a full stroke on the master cylinders if your of even a little it is very hard to bleed.
580K early has a balance tube to equalize pedal travel when both brakes are used at once. If I recall it'll allow fluid to pass to the other reservoir if gunked up.
I fougt this for quite a while as well. In my case, (get it) ha I knew that my brakes needed rebuilt from the get go. I then ultimately repacked the master cylinders. They wouldn't hold fluid at all. Glad you aren't using the "DOT" fluid. Big no no for the seals.
Welcome to HEF, Adam !
This is a difficult problem to help Amunderdog without being there with him. 6 master cylinders and none of them will pump any pressure. I would put one in a vice and prime it like any other MC. If the rod is getting full stroke they have to pump fluid unless he got 6 bad cylinders--- not likely. IMHO. I wonder if the lines are connected to the master cylinders in the correct positions. Here is the circuit for the early 580K.
Everything is like the picture shows. It is a phase three. All it good condition. the rubber hoses and rear brakes are new. They worked a little while after the brake rebuild. I checked that the rods are giving max stroke. I checked the manual. It said to fill master cylinders. I know there is fluid at front. So i pulled the pressure lines and added fluid to that end. Still not moving fluid. I tried jamming the peddles applied and opening the bleeders. To see if it would gravity feed. No The reservoir is highest point, So i was thinking of adding a small amount of pressure there. to help push the fluid thru. Maybe i just have to keep pumping the peddle until it happens?
Have you bled the air out? My first thought was the crossover tube has check valves. Press one brake pedal, the ball is forced to overcome the spring, stops flow to the other master. Press two at once, pressure is more nearly equal. neither check ball closes. A small amount of fluid moves to equalize braking effort. Mine were clogged, I only had brake when using both at once. You have no braking action. Your problem is elsewhere. Master cylinders are only slightly bigger than slave cylinders. Oil isn't readily compressible, but air will squish easily. There can be no air in your lines. Your masters are a foot or more higher than your slaves. Air won't easily escape.
Good to know about the crossovers. Will try pumping the peddles locked. May need to invest in one of those vacuum bleed tools.
I'm thinking one of two things, (1) when you rebuilt the master cylinders did you put the check ball back in the crossover ports on both masters cylinders. (2) you may have rolled or cut a brake piston seal when you installed them. First one isn't too bad the second one is not good.
Did you bench bleed the master cylinders before installation? If not you may never get the air out.
Ok. I work slow these days; But i have the brakes working. We tried gravity and pumping peddle = Fail - Tried vacuum on bleeders = Fail Bought one of those, Manual Brake Fluid Pressure Bleeder units. It applies air pressure to master cylinder reservoir at fill cap. We put 15psi on master cylinder reservoir. Found a bunch of leaks. Corrected the leaks. In 10 min the brakes were bled and working. Thank you all for helping me think about this.