Brake Repair

4 Steps to Repairing a Brake Booster


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A brake booster is simply a vacuum booster. It uses the power derived from your car’s vacuum system to boost the pressure applied to the brakes. The braking system depends on the valve in the booster. Repairing this device, therefore, requires preliminary checks and replacement of a malfunctioning vacuum booster valve. It is only after this that you can confirm the status of your booster.

You need to gather some tools and materials before you start. The tools and materials needed are:

  • Wrenches of different sizes
  • Screwdrivers
  • New check valve

You can now proceed in replacing the check valve as itemized below:

Step 1: Initial Verification Checks

Carrying out verification checks on your brake booster involves 4 simple steps:

  • Switch off the engine.
  • Pump the brake pedal until you have completely bled out the all of the fluid in the system.
  • Keep  the brake  pedal  depressed while you start the engine at the same time
  • Keep the pedal only slightly compressed after you start the engine. This confirms a refill of the fluid that is only possible if the vacuum system is intact.

If the refill fails to occur, check your hose and replace if it is faulty. If the brake hose is intact then, unfortunately, your vacuum system is faulty. This means that your brake booster is out of order and needs immediate replacement. Before replacing the entire booster, however, first check the status of your check valve.

Step 2: Check Valve Replacement

  • Look for the place where the vacuum line connects to the brake booster. The check valve is likely to be located here.
  • Identify the clamps holding the valve line to the check valve
  • Remove the clamps and take out the valve line
  • Remove the check valve, using either a wrench or an appropriate-sized screwdriver
  • Install  the new check valve in the proper location on the booster and reattach the vacuum hose
  • Restart the engine and check for a restoration of brake pressure

If the pressure is right, you are done.  If not, your booster is faulty. Proceed to replace the booster as follows:

Step 3: Brake Booster Replacement

  • Locate the break booster behind the firewall of the brake master cylinder
  • Identify the restraining clamps
  • Loosen the clamp/s  and disconnect  the vacuum line
  • Separate the master cylinder from the booster by loosening  the bolts using the appropriate wrenches
  • Disconnect and remove any brake pedal restraining bolts to completely free the damaged booster
  • Position the new brake booster behind the firewall of the master  cylinder
  • Reposition and tighten all nuts previously removed to secure the newly installed booster
  • Slide the rubber hose over the fitting
  • Reconnect the vacuum line to the booster

Step 4: Safety Tips and Final Checks

It is possible to damage the brake lines while trying to separate the damaged booster from the master cylinder. This happens because the brake lines are directly attached to the master cylinder. To prevent this occurrence, therefore, you must avoid any pressure on the brake line while attempting to separate the booster from the master cylinder.

Finally, always remember to use appropriate clothing and eye protection.

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