How to Replace a Power Brake Booster
A power brake
booster is designed
to assist the driver in the effort to make braking the car easier. By using vacuum
from the engine’s intake system and a diaphragm inside the brake booster, the braking
force can be more than doubled with minimal effort from the driver. Over the years,
a leak can develop in the system. As a result, braking assist is decreased which
usually indicates a faulty power brake booster. If this condition exists the first
step is to test the booster and replace if needed. If the booster is unable to maintain
the vacuum, it has failed. To check this,
start the engine
, allow to run
for fifteen seconds. Shut the engine off and remove the check valve from the booster.
You should hear vacuum escaping, if not the diaphragm inside the booster has ruptured
causing he malfunction. Another sign that the booster is bad is a hard brake pedal,
in other words the pedal is hard to push to make the brakes operate. Check to make
sure the vacuum hose between the brake booster and the intake manifold is not leaking
before replacing the booster. A leaking vacuum hose can cause the same symptoms.
Also, don’t panic if this happens. The brakes will still work, but the additional
force needed to stop will increase and stopping distance usually increases too.
Park your car on level ground with the engine off and the
raise a car according to the manufacturers recommended instructions and secure with
jack stands. Also be sure to wear protective clothing, eyewear and gloves.
Tool Needed to Complete this Job:
1. Wrench set
3. Ratchet and socket set
4. Different length socket extensions
Step 1. Pull the hood release to open
, release the secondary safety latch and finish opening the hood, secure
with prop rod if needed.
Step 2. The power brake booster is located on the driver’s side of the vehicle
under the hood in most cases. It will be mounted between the firewall and the
Step 3. To begin, first remove the large vacuum hose that is attached to the
Step 4. Using your wrenches, unbolt the
the brake booster (two bolts).
Step 5. Move the master cylinder just far enough forward so you will have room
to remove the booster from its mounting location. (note in some cases the master
cylinder will need to be removed).
Step 6. Now to remove the booster. Under the dash board you will see where
the brake pedal is attached to a push rod. There will be a retaining clip or cotter
pin holding the top of the brake pedal to the push rod. Using pliers, remove the
cotter pin or retaining clip.
Step 7. Next, there are four nuts that you will see around where the push rod
goes through the firewall. They secure the brake booster to the firewall. Using
your sockets and extensions, remove the nuts. This can be sometimes tight and a
little frustrating due to the location of the nuts.
Step 8. Once the nuts are removed, return back to the
area. Again, move the already
loosened master cylinder just enough to remove the booster.
Step 9. Slide the booster studs through the firewall and remove it from the vehicle.
Install replacement power brake booster and reassemble.
The power brake booster is an important component. As mentioned, there are different
ways to check it to be certain it is bad. Always remember, if it does go bad, the
brake pedal will be more difficult to press, but the brakes will work. Always drive
carefully and leave a safe distance between you and the car in front of you. Any
mechanical device can fail without warning. Allowing sufficient distance between
you and the vehicle in front of you can provide adequate time to make a safe and
logical decision in the event of any type of brake failure.
CAUTION: Brake fluid is very corrosive to your vehicle’s finish. Avoid getting
brake fluid on the painted surface of the vehicle. If you do, immediately wipe if
off and clean the area with soap and water. It has the ability to remove the paint,
so don’t wait. Check the brake pedal operation, it should be normal. Do not move
the vehicle until normal brake operation has resumed. By: Joe Feliciani
/ AKA jacobandnickolas
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Article first published 2009-07-28 (Updated 2015-01-06)