A rattle somewhere between the brake pedal and the maste cylinder. Brakes and all busings between master cylinder and wheel have been checked and rebuilt, struts need replacing but the rattle is not

As you have replaced the brake booster and master cylinder I strongly suggest you begin by rechecking the fitment to ensure any pedal linkage adjustment is correct and a clearance exists between the booster pushrod and the master cylinder piston.

Ensure the load sensing valve is correctly adjusted and is working correctly.

Check the brake at each wheel is in the condition the manufacturer would approve of and then bleed all four brakes using the most suitable method...

There are many things other than brake lines that can cause braking loss. Investigation will reveal the issue. First, check fluid level in the Master Cylinder. If the level is normal, you don't have any broken lines/leaks. If the fluid is full and you have no brake pedal/braking power, chances are the Master Cylinder itself has failed. There are o-rings internal to the M/C that can fail, and when this happens, you will lose pressure to wheel cylinders/calipers and, as a result, lose your brakes.

If the fluid has leaked out, then you need to find out fro where. This is not too difficult normally. Fill the M/C with fluid and have someone press the brake pedal while observing the underside of the vehicle. You should see fluid dripping from somewhere, often near one of the wheels. You can have a leaking caliper/wheel cylinder, brake hose, or metal brake line. Once you determine what part has failed, you can purchase and replace the defective part. Brake calipers, wheel cylinders, and hoses are fairly simple to replace. Brake lines are more difficult, as they require shaping, cutting, and the creation of couplings. After repairs are done, the brake system must be refilled and all air bled from the system or braking will not be satisfactory.

It is very difficult to diagnose this problem with the little bit of information you gave. If the brakes are drum brakes check to see if the brake cylinder is working and has no leaks, lift the rubber seals and make sure there are no leaks there, check the brake adjuster make sure that works okay. If everything works and you bled the brakes properly, then the problem is most likely is the master cylinder or the wheel cylinder.



While bleeding the brakes always make sure you check the master cylinder reservoir to make sure the fluid level is up so you do not get air in the brake lines. When bleeding the brakes did you have someone press down hard on the brake pedal hold the pressure on the brake pedal when opening the bleeder then push the brake pedal to the floor keep it there, until you tightened the bleeder, then pump the brakes up and hold it there, while you repeated the bleeding operation by opening the bleeder when the brake pedal go\'s to the floor keep the pedal down until you tighten the bleeder and then pump the brake pedal back up then check the fluid level in the reservoir, keep doing it until the brake fluid shows no sign of air.



If the brake pedal is pumping up during the bleeding process and you made sure you got all the air out of the brakes and then the pedal go\'s to the floor, make sure the fluid level is correct in the reservoir and the bleeder is closed tight and there are no leaks in the lines, wheel cylinder, brake cylinder the brake adjuster is working and master cylinder, and if you still have no brakes then it must be a defective piston in the wheel or brake cylinder, if there is a seal problem with the pistons you will not get any pressure to push the brake fluid. let me know how you are doing.

Did you ensure that the master brake cylinder was topped up properly whilst you bled the back brake shoes?

If you did so and the brakes are free of air in the lines, then you still have to adjust the brake shoes to their operating position. Secure vehicle from movement. Jack back wheels of the ground, support with jack stands. Remove the rubber grommets that covers brake adjustment wheels. Turn star wheel adjuster with special adjustment tool or a wide blade screw driver. Lock the wheels with the adjustments, push in brake pedal until you have pressure, back off adjustments until wheel runs freely. you should have plenty of pedal now. Make sure master is at the right level at all times.

If you don't have pedal now then I would suggest you still have air in the brake lines.. If you pump the brakes until you have pressure and the pedal feels spongy , then you still have air in the line somewhere. Bleed until air is removed.

Losing fluid somewhere or losing pressure in the master. Will need to be serviced by a shop. Can't drive it this way.

if a master cylinder is bad and you are sure you have all the air out and no leaks.pedal will go to floor , running or not. if booster is bad it will cause a hard pedal. but if master cylinder is bad it will turn on a brake light on dash if it works. make sure the wheel cylinders are not leaking. I beleive that the master cylinder is bad, or you have a leak somewhere. If the master cylinder is functioning properly, the brake pedal will depress to a certain depth and no further.

Check the brake fluid level in the master cylinder. If it's low or empty refill it and check for a leak. If the master cylinder is full of fluid the cylinder itself could be bad.

Is the master cylinder good? a bad master can cause this also did you bleed the master first before bleeding at the wheel and also make sure the bleeder screw is clean, if the hose is good then theres only a few things, a bad master or a master that wasnt bleed, try bleeding the master first then try rebleeding the brakes.

well, check the brake lines for leakage after adding brake fluid to the full mark. If the brake pedal goes all the way to the floor, it's likely there is a leak somewhere after the master cylinder. If the pedal gets hard after adding fluid, and pumping it several times with the car off, then the master cylinder is still ok.

If air has gotten into the master cylinder, it may have to be bled out on a bench, or using a scanner if that's the way your vehicle is.

Bleeding the Brake System (ABS) Auto Bleed Procedure NOTE: Perform a manual bleeding procedure. If the brake pedal height and firmness results are not achieved, perform the auto bleed procedure below.
NOTE: Perform this procedure when replacing the brake pressure modulator valve or electro-hydraulic control unit.

1. Perform the manual brake bleeding procedure. Refer to Bleeding the Brake System (non-ABS).
2. Check the master cylinder fluid level often to prevent running the system dry.
3. Press the brake pedal firmly and run the Scan Tool Automated Bleed Procedure (for Gas engines) once, or the Function Test (for Diesel engines) four times. Make sure to release the brake pedal between each test.
4. Perform the manual bleed procedure again. This should remove the remaining air from the brake system.
5. Bleed the system as many times as needed to obtain the appropriate feel of the brake pedal.

Check the reservoir to be sure the fluid is full. If not, top it off and try it again. If there's still trouble building pressure, pump the brakes a bunch of times, and then check around each wheel for fluid on the ground. If you see none, it's possible that you have a break in the line somewhere through the chassis and that the fluid is leaking out inside. If you see no evidence of leakage, and the reservoir is still full, you need a new brake master cylinder - what will have happened is that the diaphragm around the plunger inside the master cylinder (which moves through the cylinder when you push the pedal, and forces fluid out to the wheels) has a hole or tear in it, so instead of pushing the fluid out to the brakes, the plunger simply moves through the fluid. It never builds pressure, and your brakes don't work.