How do i install a new brake booster - 2000 Nissan Xterra

Step 1 - Locate the Brake Booster The brake booster is located adjacent to the master cylinder. There will be 4 mounting screws protruding through the booster. The booster is also attached to the brake pedal in the interior of the car. This is where you will start work in replacing the brake booster.
Step 2 - Remove the Brake Booster Start by locating the booster rod that goes through the firewall and is attached to the brake pedal on the interior of the car. Typically, there is a cotter pin that secures the rod to the pedal, but there may also be nuts. When removing any fasteners in the course of this job, make sure to retain the nuts, cotter pins, and various other fasteners as the new brake booster will not come with replacement fasteners.
Remove the fasteners, whether it is a cotter pin or nuts. Slide the rod off the brake pedal. Disconnect the vacuum brake line that connects to the booster. In the engine compartment, there are four bolts securing the booster to the master cylinder and firewall. Loosen and remove these nuts. Remove the nuts (there are usually 2 in addition to the 4 that have already been removed) that secure the brake booster to the master cylinder. Wiggle the brake booster away from the master cylinder. There is a seal between the two. You will need to keep this as the new part does not generally come with another one. Remove the brake booster.
Step 3 - Install the New Brake Booster Set the new brake booster on the four mounting screws. Tighten the nuts on the bolts to the master cylinder. Insert the push rod through the firewall. Start these by hand so that the threads are not ruined. Reattach the vacuum hose, then the nuts to the 4 mounting screws. Reattach the push rod to the brake pedal by whatever means it was originally secured with, whether by cotter pin or by bolts.
Step 4 - Bleed the Brakes You will need to bleed the brakes after replacing the brake booster

its my pleasure to answer your question how to replace the brake booster :
1 With the engine off, step on the brake pedal several times to relieve the brake booster of vacuum.
2 Press the brake pedal down and start the engine. Verify that the brake pedal sinks slightly. Turn off engine.
3 Remove the vacuum hose from the brake booster.
4 Remove the brake lines from the master cylinder. Remove the master cylinder from the brake booster. Plug the fittings to prevent brake fluid seepage.
5 Disconnect the brake pedal from the push rod.
6 Have an assistant hold the brake booster from inside the engine compartment. Remove the nuts that hold the brake booster to the firewall. These nuts are usually located under the dash on the interior of the firewall.
7 Remove the brake booster.
8 Install the new brake booster to the firewall. Tighten the mounting nuts.
9 Connect the push rod to the brake pedal.
10 Connect the vacuum hose to the brake booster.
11 Attach the master cylinder to the new brake booster and reconnect the brake lines.
.12 Bleed the brakes at the master cylinder.

The following steps will help you to replace a Toyota Camry brake booster :
1 With the engine off, step on the brake pedal several times to relieve the brake booster of vacuum.
2 Press the brake pedal down and start the engine. Verify that the brake pedal sinks slightly. Turn off engine.
3 Remove the vacuum hose from the brake booster.
4 Remove the brake lines from the master cylinder. Remove the master cylinder from the brake booster. Plug the fittings to prevent brake fluid seepage.
5 Disconnect the brake pedal from the push rod.
6 Have an assistant hold the brake booster from inside the engine compartment. Remove the nuts that hold the brake booster to the firewall. These nuts are usually located under the dash on the interior of the firewall.
7 Remove the brake booster.
8 Install the new brake booster to the firewall. Tighten the mounting nuts.
9 Connect the push rod to the brake pedal.
10 Connect the vacuum hose to the brake booster.
11 Attach the master cylinder to the new brake booster and reconnect the brake lines.
.12 Bleed the brakes at the master cylinder.

12 specific steps will help you :
1 With the engine off, step on the brake pedal several times to relieve the brake booster of vacuum.
2 Press the brake pedal down and start the engine. Verify that the brake pedal sinks slightly. Turn off engine.
3 Remove the vacuum hose from the brake booster.
4 Remove the brake lines from the master cylinder. Remove the master cylinder from the brake booster. Plug the fittings to prevent brake fluid seepage.
5 Disconnect the brake pedal from the push rod.
6 Have an assistant hold the brake booster from inside the engine compartment. Remove the nuts that hold the brake booster to the firewall. These nuts are usually located under the dash on the interior of the firewall.
7 Remove the brake booster.
8 Install the new brake booster to the firewall. Tighten the mounting nuts.
9 Connect the push rod to the brake pedal.
10 Connect the vacuum hose to the vacuum brake booster.
11 Attach the master cylinder to the new brake booster and reconnect the brake lines.
.12 Bleed the brakes at the master cylinder.

It is a generic Nissan brake light switch replacement procedure... the brake light switch on a Nissan Altima i.e. controls the illumination of the brake lights. Without the switch, the lights would not go on. The switch has no service life, so when it goes, it usually happens suddenly. New brake light switches can be obtained from Nissan or from a Nissan dealership.

1. Remove the cotter pin from the pin bolt that holds the brake pedal to the brake booster with a pair of pliers. There is a small cotter pin running through the brake pedal to brake booster connection. You need to pull this cotter pin out to remove the larger pin that holds the brake pedal to the brake booster.
2. Slide the pin out of the brake booster mounting bracket.
3. Pull up on the brake pedal to slide it out of the brake booster mounting bracket.
4. Remove the bolts holding the brake switch to the firewall using a socket wrench.
5. Remove the electrical connector on the brake switch by pulling it straight off the switch.
6. Slide the switch off the firewall.
7. Install the new switch. Installation is the reverse of removal. Make sure that you replace the cotter pin in the brake booster to brake pedal connection. The cotter pin prevents the retaining pin in the brake booster mounting bracket from coming off.

Hope helps (remember to rate this answer).

from autozone.com:

1. Disconnect the negative battery cable.
2. Apply the parking brake.
3. Unplug all necessary electrical connections.
4. Remove the master cylinder from the booster and pull it off the studs, CAREFULLY! It is not necessary to disconnect the brake lines.
5. Disconnect the vacuum hose from the check valve.
6. If necessary, remove the brake light switch.
7. Disconnect the booster pushrod at the brake pedal.
8. Remove the booster mounting nuts, located on the inside of the firewall.

Fig. Fig. 1: Vacuum booster mounting

1. Lift off the booster and remove the gasket.

To install:

1. Install the booster with a new gasket.
2. Tighten the booster mounting nuts to 21 ft. lbs. (29 Nm) on all except 1996-98 models. On 1996-98 models, tighten the nuts to 26 ft. lbs. (36 Nm).
3. Install all remaining components.

It is the booster, but it might not be abnormal.

Vacuum from the engine is supplied to the booster, and vented if the brakes are not being applied.

When you step on the pedal, the movement of the pedal blocks the vents, allowing the vacuum to build up. That vacuum then pulls on a diaphragm, assisting you in applying the brakes.

Most people can’t hear that venting, some can.

You should, of course, have it checked out, but it sounds as if this might be normal operation.

The booster is bolted to the firewall, and then the brake master cylinder is bolted to the forward side of the booster.

To replace it you disconnect the brake pedal, remove the master cylinder, take the vacuum line off the booster, unbolt it from the firewall.

Install the new booster by reversing these steps.

But I don't think you need one, from what you say.

1. Step 1 Mark the brake lines coming into and out of the master cylinder using masking tape and permanent marker.
   
2. Step 2 Orient the tube wrench so that it grabs the end of the nut by first sliding it over the brake line.
   
3. Step 3 Pull the brake lines out of the master cylinder.
   
4. Step 4 Unbolt the two bolts that hold the master cylinder to the brake booster.
   
5. Step 5 Slide the master cylinder off the brake booster.
   
6. Step 6 Remove the bolts that hold the brake booster to the firewall.
   
7. Step 7 Remove the cotter pin from the pin holding the back of the brake pedal to the master cylinder.
   
8. Step 8 Slide the brake booster to brake pedal pin out of the mounting bracket.
   
9. Step 9 Pull the brake booster off the firewall.
   
10. Step 10 Install the new brake booster. Installation is the reverse of removal.
    

a defective master has just one common symptom, a soft sinking pedal.
Instructions Things You'll Need:

• Nose pliers
• Ratchet and socket
• Ratchet extension
• Slip joint pliers
• Wrench
• New cotter pin

Removing the Old Brake Booster
1. Step 1 Park your car in a safe place with enough room to work around the front and driver side of the vehicle.
   
2. Step 2 Locate the booster push rod connected to the brake pedal.
   
3. Step 3 Remove the cotter pin securing the booster push rod pin to the brake pedal using a pair of nose pliers.
   
4. Step 4 Release the push rod pin from the brake pedal and slide the push rod off the brake pedal.
   
5. Step 5 Unscrew the four mounting nuts off the brake booster studs using a ratchet, ratchet extension and socket. You should be able to see the four booster studs extending through the firewall, in front of the brake pedal.
   
6. Step 6 Disconnect the vacuum hose from the brake booster, working from the engine compartment. Use a pair of slip joint pliers.
   
7. Step 7 Remove the two nuts holding the brake master cylinder to the brake booster. Use a wrench or ratchet and socket.
   
8. Step 8 Separate the brake master cylinder from the booster just enough to make room for booster removal.
   
9. Step 9 Pull the brake booster off the firewall and remove it from the vehicle.
   Installing the New Brake Booster
10. Step 1 Set the new booster in place by sliding the push rod and four mounting studs through the mounting holes on the firewall.
    
11. Step 2 Slide the brake master cylinder flange over the two mounting studs on the brake booster.
    
12. Step 3 Start the two brake master cylinder mounting nuts by hand to avoid damage to the threads.
    
13. Step 4 Tighten the two brake master cylinder mounting nuts using a wrench or ratchet and socket.
    
14. Step 5 Connect the vacuum hose to the brake booster.
    
15. Step 6 Screw the four mounting nuts to the brake booster working from inside the vehicle. Start the nuts by hand to avoid damaging the threads.
    
16. Step 7 Tighten the four mounting nuts using the ratchet, ratchet extension and socket.
    
17. Step 8 Position the brake booster push rod over the brake pedal and slide the push rod pin.
    
18. Step 9 Install a new cotter pin to secure the booster push rod to the brake pedal
    

get ready for some work.you need to remove the master cylinder nuts that hold master cylinder to brake booster.once you remove nuts you have 2 choices remove master cylinder to remove booster. to keep from bending brake lines.or you can leave master cylinder in pull it toward you easily careful dont bend lines .disconnect vacuum line at booster .go inside vechicle to floor on driver side loosen four nuts on floor to booster .disconnect power brake push rod from brake pedal .dont force pushrod to the sides when disconnecting it.remove four booster nuts then remove booster.when in stalling the new booster loosely install four nuts then connect the push rod to the brake pedal .install new clip tighten the booster unit .if you decide to remove master cylinder use inline wrenches on master cylinder to remove lines.also plug the master cylinder brake line holes to keep from losing all brake fluid.