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I have a 98 Chevy Blazer 4.3 liter I was driving down the road coming home when I went to apply the brakes the pedal went to the floor but I did not slow down nor stop I had to use a hill in order to stop and it wasn't 5 mins ago when they worked just fine. the next day I checked brake fluid and it was full and I have plenty of brake pads not crystallized what would cause my vehicle not to be able to stop?

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If your brake pedal went to the floor it means that there was not enough hydraulic pressure to apply the brake. If they were working fine before and never felt squishy then your master cylinder has probably gone out and needs to be replaced.

Alternatively you may have a lot of air in the lines, enough that the pressure applied by the brake was not enough to stop the car.

Either way it isn't safe to drive until you know that the brakes are functioning properly

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If you have fluid in the brake reservoir, and have no pedal, you have a failed master cylinder. The piston that moves when you step on the brake pedal has o-ring seals that if they fail, can allow fluid to pass by them and not apply pressure to the brakes. All brake systems today have a dual circuit system where if you loss pressure to a wheel (caliper, wheel cylinder, etc), you will still have brakes in the other circuit.

It sounds from your description that you had no brakes and after pumping it, they came back. That is classic master cylinder failure where the o-ring seals are failing and fluid moves past them and pumping brings back pressure. Take it to a competent service station and have the master cylinder checked or replaced.

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You need to bleed the brakes, you will have an air pocket in the system. As you stand on the pedal, the system is compressing the air pocket instead of the fluid, hence the brakes won't actuate.

Here's a popular mechanics article on how you can do this yourself, or you can take it to a mechanic and they can do it pretty quickly and cheaply for you.

This should also make you want to check the condition of the brake lines and master cylinder. If you haven't changed the brake fluid in a while, it might mean that there is a leak somewhere that is letting air in to the system.

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What is described here is classic excessive water in the brake fluid.

The previous application of the brakes prior to failure heated the calipers enough to boil the moisture in the brake fluid and fill the calipers with water vapour (steam), forcing the brake fluid back in to the reservoir.

On the next application, the pedal forces fluid into the calipers which does nothing other than to compress the steam back into the fluid. This is evidenced by the fact that after the brakes had cooled overnight and the steam had condensed back to water they worked fine. The required remedy is a total brake fluid flush with new fluid from a sealed container of the appropriate type.

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