Is it normal that the brake pedal drops when the engine runs?

One of the worst situations is when you hit the brake pedal and it goes to the floor when the engine is going fast. This is nasty and dangerous. Driving without working brakes is discouraged.

If you notice weak brakes or an odd sound, get the car checked out immediately. This article will explain why the brake pedal is mushy when the engine is running and how to fix it for full-power brakes.

Why Brake Pedal Drops When Engine Runs?

Source: safetybrakeandclutch

1. Brake Fluid Loss

High brake power depends on brake fluid. The brake pedal depressing compresses the brake cylinder piston. Compression raises brake line pressure, moving braking fluid particles to the caliper. braking pads push into the braking rotor due to high brake fluid pressure.

2. Bad Master Cylinder

The brake pedal press should feel strong under your thigh because it’s connected to the master cylinder via a push rod. Master cylinder hydraulic pressure activates brakes and transfers braking fluid to the front and rear wheels.

Sealing the master cylinder keeps pressure and power, pushing braking fluid to the calipers. Thus, worn or damaged rubber seals that hold brake fluid within cause internal leaks, causing the spongy feel under your calf.

3. Brake ccc Issue

When the brake pedal reaches the bottom, the brake power booster may fail. The power booster assists the driver in braking. You don’t need much power to stop the car. The engine-connected brake booster is located between the master cylinder and the brake pedal.

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It overcomes brake fluid pressure with a vacuum line. A malfunctioning brake booster increases stopping distance. Completely stopping the car requires the pedal to the floor. This is because you are not obtaining enough power to stop the car.

4. Air in Brake Lines

Many drivers remark that the brake pedal drops after replacing the master cylinder. This usually occurs when the brake lines have air after installing a new master cylinder without air bleeding. Air blocks brake fluid from flowing smoothly inside brake lines, harming them and making the brake pedal feel spongy instead of firm.

How Do You Fix Brake Pedal Drops to Floor When Engine Is Running?

While dangerous, having your brake pedal go to the floor while the engine is running is apparent and easy to detect. This problem involves a few braking system parts. Start diagnosing the issue to fix it:

Brake Lines, Callipers Check: When the brake pedal goes to the floor while the engine is running, the immediate thought is that a brake line leak is releasing braking pressure. You must first check the brake fluid level. Full capacity means no leak. If not, a leak exists.

In case of leaking, examine one of the four wheels for oil residue. Next, inspect the brake fluid lines for holes. Complete by repairing the damaged part and adding brake fluid.

Brake Master Cylinder: Since it has seals to keep oil inside, inspect it next. Due to the car’s age, these seals may wear out and leak brake fluid. Replace the master cylinder in this case.

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