Do you have to remove brake lines when you change the brake booster

it seems like the master cylinder is not pumping any fluid. Here are some possible reasons why this could be happening:

Air in the brake lines: If there is air in the brake lines, it can prevent the master cylinder from pumping fluid. You may need to bleed the brake lines to remove the air. Here is a video that demonstrates how to bleed brakes on a Chevy Suburban.

Master cylinder failure: If the master cylinder is faulty, it may not be able to pump fluid. In this case, you may need to replace the master cylinder. Here is a video that shows how to replace the master cylinder on a Chevy Suburban.

Brake booster failure: If the brake booster is faulty, it can cause the master cylinder to not pump fluid. In this case, you may need to replace the brake booster. Here are brake booster tests: How to Test a Brake Booster: 4 Simple Diagnostic Tests (wikihow.com)

Hi and welcome to FixYa!

The master cylinder is surely worn out. The right side piston seal is surely stuck and replacement will surely be necessary to make it loose and make the brakes work again.

Hope you find this information helpful enough and thank you for using FixYa! Have a good one!

The booster is working properly if the pedal goes down a little when starting the truck. Seems more like it's a master cylinder problem if it won't pump up.

REMOVAL & INSTALLATION Fig. 1: Disconnect the warning indicator at the master cylinder
Fig. 2: Remove the fluid to minimize the amount that would otherwise inevitably be spilled
Fig. 3: Unscrew the line fittings at the master cylinder
Fig. 4: Hold a rag under the fittings to keep fluid from dripping all over things
Fig. 5: Unbolt the master cylinder from the brake booster
Fig. 6: Remove the master cylinder from the vehicle and set it in a clean location

1. Disconnect the negative battery cable.
2. Apply the brake pedal several times to exhaust all the vacuum in the system.
3. Detach and cap the brake lines from the master cylinder.
4. If equipped, detach the brake warning indicator connector. NOTE: A turkey baster (tapered tube with a squeeze ball on top) works well for removing fluid from the reservoir (see photo).
   
5. Siphon off the fluid from the master cylinder reservoir to minimize spillage when lines are disconnected.
6. If applicable, disconnect and cap the Hydraulic Control Unit (HCU) supply hose at the master cylinder reservoir and secure in a position to prevent loss of fluid.
7. Unfasten the 2 nuts and lockwashers that attach the master cylinder to the brake booster.
8. Remove the master cylinder from the booster by sliding it forward and upward from the vehicle. To install:
   
9. Install a new seal in the groove in the master cylinder mounting face.
10. Position the master cylinder assembly over the booster pushrod and onto the 2 studs on the booster assembly.
11. Install the retaining nuts, then tighten to 18–25 ft. lbs. (24–34 Nm).
12. Uncap and connect the brake lines to the master cylinder. Tighten the front fitting to 16–21 ft. lbs. (21–29 Nm), and the rear fitting to 10–15 ft. lbs. (15–20 Nm).
13. Uncap and connect the HCU hose to the master cylinder reservoir fitting and secure with a hose clamp.
14. If equipped, connect the brake warning indicator.
15. Fill the master cylinder with Heavy Duty Brake Fluid C6AZ-19542-AA or equivalent DOT 3 brake fluid from a clean, sealed container. Bleed the entire brake system, as outlined in this section.
16. Connect the negative battery cable.
17. Operate the brake several times, then check for external hydraulic leaks.

Are you losing any Brake Fluid? Is it visible anywhere at the four wheels? Is it visible anywhere else?
The Master Cylinder may be defective. When you bled the Brakes did you maintain proper Brake Fluid Level in the Master Cylinder? If you didn't: and air entered into the Master Cylinder there maybe air within in the system in the Master Cylinder. You can bleed the Master Cylinder by removing the brake lines, adding more fluid, pumping the brakes, bleeding the air out of the system.
Are you losing Brake Fluid and can't find a noticeable leak? Then there is a good posibility that the rear seal in the Master Cylinder is leaking and the Fluid is going into the Brake Booster - which is the large wheel shaped drum located on the fire wall. In this case both the Brake Booster and the Master Cylinder will have to be removed and replaced. The Booster contains seals that Brake Fluid is very caustic to and will ruin these seals- causing future failures.
If no Brake Fluid is lost, no leak found: Check the Brake Booster Vacuum Advance. This should be connected to the outside of the Booster, attached to a hose, with the hose going to the engine. Check to see if this is working properly. Replace if needed.

1. What is the Brake Fluid Level?
2. Are you losing any Brake fluid at all? Are there any puddles or noticeable wetness on the ground or on the tires/wheels? With vehicle parked, the reservoir filled (overfilled), and engine running: pump the brakes and check on the ground and back sides (inside portions) of the wheels. Look for any brake fluid leaks.
3. Leaks from Calipers usually means a leak from the caliper piston. The rubber seals will be wet.
Leaks from Drums usually means a leak from the wheel cylinder.
4. In any case of leaks from the wheels - replace the calliper OR wheel cylinder.
For caliper leaks: change the brake pads, and clean the rotors with brake cleaner.
For drum leaks: clean the drum and brake hardware with brake cleaner, and replace the shoes.
5. If no leak is detected from the wheel area's: check under the Master Cylinder for wetness indicating a possible leak.
6. If no leak can be found: you MAY have a rear seal leak in the Master Cylinder which is pumping Brake Fluid into the Brake Booster (that large disk looking thing attached to the fire wall, attached to the Master Cylinder in front).
a. Use a large drip/catch pan under the Van in the area on the Master Cylinder.
b. Disconnect the brake lines from the Master Cylinder using a flair wrench.
c. Remove the two nuts (12 or 13mm?) attaching the Master Cylinder to the Brake Booster. If you have been using a lot of fluid, and have found no leaks, here is a good possibilty that all that brake fluid has collected in the Booster; so when you detach the Master Cylinder from the Brake Booster, all that fluid will come rushing out!
7. If there is Brake Fluid inside the Brake Booster: there is no cleaning that out. Brake Fluid is very caustic to the seals inside the Booster and should be replaced.
8. Of course the Master Cylinder will also have to be replaced.
9. After replacing the Master Cylinder/Brake Booster - make sure you get all that spilled brake fluid off the engine compartment area parts! I use a brake cleaner, then mild soap and then water to rinse. Clean any Brake Fluid off Paint imediatley as it will quickly dissolves finishes and paint.
10. If no leak is detected and the Booster is clear, there may be problems with the Booster One-Way Valve. This is attached to the outside of the Booster and has a hose from an "advance" connected to it. This maybe malfunctioning where you are losing power. Replace this first before deciding to replace the whole booster (in cases of NON-LEAKS ONLY). If that did not work, there may be inner seals inside the Booster that have failed. That means a new Booster.
11. In any of the above cases: Make sure you bleed the Master Cylinder correctly and bleed the brakes (at each affected wheel) correctly. Any air in the brake lines will decrease your braking proficiency or could result in brake failure.

Let me know if this helped or if you have any additional information or questions. Feel free to contact me at FixYa.com!

do you see any fluid on the ground? if not...master cylinder is bad...vaccum is sucking brake fluid into the booster....is your car running poorly sometimes...if so the vaccum is also sucking it into the engine.....120$ should fix this at any brake shop

bad power booster

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.

i do agree with the haynes manual.

First off, pb blaster is your best friend for brake line bolts. You want to **** as much of the brake fluid out of the resivour as you can, Then you need to get the brake lines off the master cylinder that is on there. make sure you use the right size flare nut wrench when you are taking the lines off. rounding off brake line bolts is not fun, trust me. once the lines are off, ( turn counter clockwise) Just make sure you have a towel to put under the brake lines. for excess fluid. then with a ratchet, and extension, and socket you need to take the master off the brake booster. Also disconnect any electrical connectors and keep them clear ofthe brake fluid. When you have the 2 bolts out of the brake booster, the master should pull out and then your ready to work on installing the new one. when you get a new ,master, you can either bench bleed it, or if you want to, you can also install the new one, line up the hole in the brake booster, put the 2 bolts back on, then you need to bleed the master. Most come with instructions.

1. Begin by removing the cap.
2. Follow the directions that come with the kit to select the suitable adapters, and then connect the adapters and tubes to the ports on the cylinder. The other ends of the tube extend down into the master cylinder, and are held in place by a plastic clip.
3. With the bleeder kit installed, fill the master cylinder about halfway with new brake fluid. Use a large screwdriver to depress the valve assembly inside the master cylinder. If you do not have a vise you can mount the master cylinder on the vacuum brake booster and bleed the master cylinder.
4. Small bubbles will appear in the fluid. Continue working the valve assembly until no more bubbles appear. This indicates that the cylinder has been thoroughly bled.

once it is bled then you hook up the brake lines, and bleed all the brakes. starting with the furthest from the master cylinder. Passenger rear, driver rear, passenger front, driver front. make sure you check the brakes to make sure there is no air, better to be safe then sorry. also, check anything you had disconnected, to make sure it is not leaking.

In simple terms, by just looking at it, you can figure out how to do the master cylinder, but to be safe, get a repair manual.

if you can see a good amount of wet brake fluid between the brake master cylinder and the brake booster. and you have been adding fliud often,you could have a bad master cylinder. it has to be replaced not rebuilt. you however may have a far more common problem, a rusted through brake line.have someone pump the brake pedal, than look under the car for a brake fluid leak ,repair as needed. than bleed the brakes for a good hard brake pedal
good luck chris