My brake pedal depresses to the floorboard, is this possibly master cylinder related and new seals are required?

PEDAL FALLS AWAY
A brake pedal that falls away under steady foot pressure is generally the result of a system leak. The leak point
could be at a brake line, fitting, hose, or caliper. If leakage is severe, fluid will be evident at or around the leaking
component.
Internal leakage (seal by-pass) in the master cylinder caused by worn or damaged piston cups, may also be the
problem cause.
An internal leak in the ABS or junction block may also be the problem with no physical evidence.

LOW PEDAL
If a low pedal is experienced, pump the pedal several times. If the pedal comes back up worn linings or rotors are
the most likely causes. The proper course of action is to inspect and replace all worn components.

SPONGY PEDAL
A spongy pedal is most often caused by air in the system. However, substandard brake lines and hoses can also
cause a spongy pedal. The proper course of action is to bleed the system, and replace substandard quality brake
hoses if suspected.

DIAGNOSIS AND TESTING - MASTER CYLINDER/POWER BOOSTER
1. Start engine and check booster vacuum hose connections. A hissing noise indicates vacuum leak. Correct any
vacuum leak before proceeding, also ensure booster mounting nuts are torqued correctly.
2. Stop engine and shift transmission into Neutral.
3. Pump brake pedal until all vacuum reserve in booster is depleted.
4. Press and hold brake pedal under light foot pressure. The pedal should hold firm, if the pedal falls away master
cylinder is faulty (internal leakage).
5. Start engine and note pedal action. It should fall away slightly under light foot pressure then hold firm. If no pedal
action is discernible, power booster, vacuum supply, or vacuum check valve is faulty. Proceed to the POWER
BOOSTER VACUUM TEST.
6. If the POWER BOOSTER VACUUM TEST passes, rebuild booster vacuum reserve as follows: Release brake
pedal. Increase engine speed to 1500 rpm, close the throttle and immediately turn off ignition to stop engine.
7. Wait a minimum of 90 seconds and try brake action again. Booster should provide two or more vacuum assisted
pedal applications. If vacuum assist is not provided, booster is faulty.

POWER BOOSTER VACUUM TEST
1. Connect vacuum gauge to booster check valve with short length of hose and T-fitting.
2. Start and run engine at curb idle speed for one minute.
3. Observe the vacuum supply. If vacuum supply is not adequate, repair vacuum supply.
4. Clamp hose shut between vacuum source and check valve.
5. Stop engine and observe vacuum gauge.
6. If vacuum drops more than one inch Hg (33 millibars) within 15 seconds, booster diaphragm or check valve is
faulty.

POWER BOOSTER CHECK VALVE TEST
1. Disconnect vacuum hose from check valve.
2. Remove check valve and valve seal from booster.
3. Use a hand operated vacuum pump for test.
4. Apply 15-20 inches vacuum at large end of check
valve.
5. Vacuum should hold steady. If gauge on pump indicates
vacuum loss, check valve is faulty and
should be replaced.