So I replaced the brake booster on my wife’s 2003 Sunfire this weekend and thought I would offer some advice since I couldn't find much info on it anywhere. I will post a picture to coincide with the numbers later on.

Ok first thing, make sure the engine is nice and cool, you are going to be getting your hands down into the engine quite a bit and may even need to brace yourself on different parts, so this is extremely important.

Engine compartment:

1. Remove vacuum hose1 by pulling the check valve straight out of the booster. Use pliers to pry open the clip and slide it down the hose and then remove the old check valve by wiggling it out of the hose. The new booster comes with a new check valve.

2. Remove the power connector2 from the Brake Fluid Level Sensor by prying up the clip and sliding it off. Tuck it somewhere safe.

3. Remove 2 nuts that hold the master cylinder and a metal bracket to the brake booster. The master cylinder should now be loose and supported only by steel brake hoses.

4. That same metal bracket also connects to the combination valve where all the brake lines meet and then route to the appropriate wheels. Remove 2 bolts holding the bracket to the combination valve. Take the metal bracket out. The combination valve should now be supported only be steel brake hoses.

5. Remove the air duct3 connecting the air box to the air filter.

6. Remove the air filter cover and air filter4.

7. Remove the Purge Valve Solenoid5. You'll see it mounted above the power steering fluid reservoir; it has a green screw on cap. There is one screw holding the solenoid in place. Remove the screw and the solenoid can be moved out of the way.

Cabin:

1. Remove the front seat by removing the 4 nuts holding the seat to the floor and remove the power connector from the air bag sensor on the bottom of the seat by prying up the clip and sliding it off. Take the seat out. You don’t have to do this, but I found it MUCH easier to access the booster’s bolts with this out of the way. You can actually just lie down in the floor pretty comfortably.

2. The brake booster is attached to the brake pedal via a shaft coming out of the back of the booster that is connected to a pin on the brake pedal. Remove the clip at the end of the pin by prying it up and off the pin. There is also a piece of white foam on the pin, take that off and slide the brake booster shaft off the pin completely.

3. Remove the 4 nuts holding the brake booster in place. They are 15mm. You shouldn't need a universal connector or an extender, but a deep socket is required.

Removal

Now the hard part: removing the booster. The factory booster is a little fatter than the one I bought from AutoZone and I had a hard time getting it out. Even with the air duct, the purge valve solenoid, and that metal bracket out of the way, there is still not very much room to get it out. There is also peg6 that one of the hoses clips onto that can't be removed that will get in the way.

You pretty much have to force the master cylinder and combination valve back to where the air duct was. It helps if you have a friend to hold them back while you pull the booster out. Once the booster shaft is clear of the hole in the firewall, I suggest flipping it over and using that shaft as a handle to pull it out. It won't be easy, trust me, but you can do it.

Once it's out, there is a foam gasket that you will need to save from the old booster that seals the firewall and the inside of the car. It's a square piece of foam with a circle cut out of the middle for the shaft and a hole in each corner for the bolts.

There is also a metal rod that goes into the center of the booster; it is roughly the shape of a piece of chalk with one end rounded off. It was stuck in the old booster, but fell right out of the new one, so I kept it in my pocket until I got the new booster in place.

Reassembly

1. Make sure the foam gasket is on the booster and lower it into the engine compartment making sure to get the shaft into the hole in the firewall and the bolts into the appropriate holes. The vacuum port should be on the upper left side if you're looking at it front the front.

2. With new booster in place, have someone hold it while you replace the 4 15mm nuts under the dash.

3. Slip the booster shaft back onto the pin on the brake pedal. Replace the foam piece and clip.

4. Put the front seat back into the car and reconnect the air bag sensor.

5. Bolt the seat back down.

6. In the engine compartment, bolt the metal bracket back onto the combination valve.

7. Insert the metal rod into the center of the booster, rounded side out.

8. Get the master cylinder in place on the booster. It might be difficult depending on how much you had to move it to get the booster out because some of the steel brake hoses might have bent slightly. If so it will want to pop off of the bolts.

9. Hold the master cylinder to the booster and slide the metal bracket over the bolts and hand tighten the nuts to keep the whole thing from popping off. Once the 2 nuts are on you can fully tighten them.

10. Reattach the Purge Valve Solenoid.

11. Replace the air filter and air filter cover.

12. Replace the air duct.

13. Reconnect the brake fluid level sensor.

14. Fit the new check valve into the vacuum hose and reattach the clip. Plug the check valve into the booster. You might need to adjust the fit a little by adjusting the hose/clip to get it to stay flush.

This is an awesome post but am not looking forward to it.

Hello, Im looking for some advice. I recently had my booster out of the car to replace a power steering line. when I reinstalled the booster it went back in pretty easily...now when I press on brake pedal it makes a whoosh of air and has a crunching sound. Doesn't seem to effect idle too much, but something not right. Rod looks centered, Bad diaphragm? Did the usual test by pumping brake then starting engine...peddle dropped down normally. Any ideas?

Is the procedure the same for 97 models as well? Because I posted in another thread about hissing on or around my BB area so I intend to check it out.