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How do I know if my brake booster is defective?

How do I know if my brake booster is defective?

Does your brake system seem to be acting up? It could be a problem with the brake servo! The brake servo is a vital part of the braking system. Its failure can lead to serious driving problems, so you need to be aware of the following symptoms so you can get it repaired immediately.

Symptoms: How to tell if the brake booster is faulty

The brake booster, which connects the brake pedal to the master cylinder, is known to suppress high fluid pressure by using the vacuum stored inside. With this servo, the driver doesn't have to apply extra pressure to the pedal when stopping or slowing down. Let's find out if the booster or master cylinder is faulty.

Must apply more force to the brake pedal

The main indicator of a faulty booster is a brake pedal that is extremely difficult to depress. This problem can occur gradually or all at once. The brake pedal hardens and you must apply more pressure than usual to brake properly. The check valve is responsible for controlling the pressure in the master cylinder. When this valve starts to have a problem, it turns the soft, smooth pedal into an aggressive, hard brake pedal.

Vehicle stops at a longer distance

In addition to a hard brake pedal, you may notice that the vehicle takes longer to stop. This is because you're not getting the force you need to stop the vehicle properly. When air bubbles enter the brake lines through the master cylinder, the pressure is reduced, causing the brakes to apply very lightly.

Engine stalls when brakes are applied

If the brake booster fails, it may draw excess vacuum from the engine. This happens when the diaphragm inside the booster fails, allowing air to bypass the seal. The brakes are then applied, the engine feels like it's stalling, and idle may stop. In addition to reduced braking performance, a stalled engine can cause serious problems.

Stalling the engine

When the diaphragm inside the brake booster fails, it allows excess vacuum from the engine to enter the system. As a result, when you apply the brakes, the engine stalls, which can lead to more serious problems down the road.

Other problems

  • The brakes no longer release properly when you take your foot off the brake pedal.
  • Your car is emitting white smoke from the exhaust and there is an unexplained drop in brake fluid at the master cylinder.
  • The brake pedal sticks in an abnormal position.
  • You hear a strange noise when braking.

How to test a brake booster

The first test is to make sure the vacuum hose is working properly.

Start by checking the vacuum hose, fittings, and check valve. In general, booster failures occur at these points. To check the booster vacuum hose, follow these steps:

  • Apply the parking brake and open the canopy.
  • Visually inspect the hose that connects the brake servo to the intake manifold.
  • If you find hardened spots, cracks, or swollen areas, the hose probably needs to be replaced.
  • Check the valve that connects the hose to the brake servo. It must allow unrestricted flow to create the necessary vacuum.
  • Disconnect the hose from the intake manifold and blow into it. If air comes through, the check valve needs to be replaced to properly block the air.
  • If you notice wet spots on the bottom of the brake servo, brake fluid may be leaking. In this case, the master cylinder may be affected and must be replaced.
  • To check for a vacuum leak: idle the engine and spray soapy water along the intake manifold. If bubbles are sucked up, the hose is punctured, causing a vacuum leak when the brake servo is used.

Checking the brake booster

If you've performed the previous tests and the hoses and booster are in good condition, you should now attempt to test the brake servo. An easy way to test the brake servo is to use the brake pedal:

  • Sit behind the wheel in neutral and apply the handbrake. Start the engine and let it idle for two minutes, then turn it off.
  • Depress the brake pedal 4 times, holding your foot down the fourth time.
  • Start the engine again. Normally, the brake pedal should move down slightly. If it does not, the vacuum in the brake servo is not strong enough.
  • To continue, remove your foot from the pedal and turn off the engine.
  • Press the brake pedal 4 times: if it moves up after the second or third press, there is probably a problem with the booster, or a leak is affecting its performance.

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