Basically you don't stop
a heater does not have a master cylinder; 'master cylinder' goes with assisted braking.
Replace it. It's what we call "blow-by", the seals are shot.
What cylinder? Master (brake) cylinder? Rear Brake cylinder? Lock cylinder?
If the master cylinder reservoir is empty, you have a leak somewhere. If the master cylinder reservoir is full, the master cylinder is bad.
The brake master cylinder is what pushes brake fluid to each wheel when you press on the brake pedal. If it's bad or marginal, your braking will suffer or disappear entirely! This is something that you need to address right away! FriPilot
The clutch pedal assembly has a clutch rod that pushes in on a clutch master cylinder. There is a hydro line that goes from the master cylinder to the slave cylinder.
The clutch master cylinder is under the hood, drivers side, on the firewall. It is between the brake master cylinder and the drivers side fender. The cylinder is very small in comparison to the brake master cylinder. It goes through the firewall and connects to the clutch linkage under the dash.
There are two normal causes. The clutch is worn out or there is a leak in the hydraulic clutch slave or master cylinder. To check the clutch, press the clutch slave cylinder down. If the clutch slave cylinder bellows compresses down to the slave cylinder, the clutch is worn out. Check the clutch master cylinder fluid level. if this is low, then the clutch cylinder need to be checked. To check for a hydraulic leak in the clutch slave cylinder, remove the cylinder's bellows and check for any fluid. If fluid is present, rebuild or replace the cylinder and bleed the system. To check the clutch master cylinder, check the back the of clutch master cylinder for leaks. If fluid is present, replace or rebuild clutch master cylinder and bleed the system. In my experience, hydraulic leaks occur at the clutch slave cylinder.
The most common sign of a failing master cylinder is when you stop and while sitting there with your foot on the brake pedal, it slowly goes down toward the floor. Replace it immediately.
It means your master cylinder needs to be replaced or rebuilt. The seals inside the cylinder can go bad and cause this to happen.
The firing order on a 1980 Toyota 4-cylinder is 1, 3, 2, 4. The distributor goes in a clockwise direction.
When you press and hold the brake pedal it will slowly move to the floor. It can also have a catastrophic failure and go straight to the floor with no stopping ability at all. If you hold the brake pedal down and it slowly moves to the floor any at all, replace the master cylinder.