Technically there are two main causes that would make the brake pedal sink all the way to the floor.
Brake pedal goes to floor after bleeding.
Low brake fluid level.
After replacing master cylinder and bleeding the brake lines pedal goes to the floor and brakes are not applied.
Brake pedal goes to the floor after bleeding the brakes.
If the brake shoes are worn the air gap between the shoe and the drum will be enlarged making the brake pedal travel downward beyond its normal throw.
Brake pedal goes to the floor and van does not stop after replacing master cylinder and bleeding system.
Brake lines brake calipers check.
A brake pedal that feels mushy spongy or that slowly sinks to the floor when depressed can be best described as brake pedal sink.
Had a leak on steel line over rear axle.
If it is full capacity then there is no leak.
Changed all steel line at rear plus calipers and brake hoses.
Check your brake fluid.
The leak may coming from a brake line or one of the brake calipers.
In case your car has a drum brake system after the above most common reasons for brake pedal goes to floor check your car s rear brake shoes.
Bled all lines front rear repeatedly but the pedal still goes to the floor.
One of the reasons is the brake system loses pressure from an external brake fluid leak.
If you step on the brake pedal and it has little to no pressure and goes all the way to the floor especially if you re getting no braking.
No brake pressure pedal goes to floor.
The brake pedal will go to the floor and subsequent efforts to get a satisfactory brake pedal will fail.
If it s low top it off to the mark on the side of the reservoir.
Pedal was soft and would go to the floor unless it was pumped.
Follow the vehicle s manufacturer specified bleeding procedure.
The first thought that comes to anyone s mind when brake pedal goes to the floor when engine running is that there is a leakage in any of the brake lines that outflow the pressure in the brake system the first thing you require is to check the brake fluid level.
Ensure master cylinder is bench bled prior to installation.
If your brake pedal sinks towards the floor when you are stopped while your foot is on the brake or does not feel as firm when the brakes are applied this could indicate you are having some sort of trouble with.