Volvo Forums - Volvo Enthusiasts Forum

Volvo Forums - Volvo Enthusiasts Forum (https://volvoforums.com/forum/)

- Volvo S80 (https://volvoforums.com/forum/volvo-s80-18/)

- - booster: (https://volvoforums.com/forum/volvo-s80-18/booster-6962/)

tech,

whats the procedure on replacing that brake booster? How long does it take? Is the booster located underneath the fusebox in the front?

It is a Pain.
If you are series about doing it your self I will do a write up but will take a while to get it done.

Will take you about 2 to 3 hours.

My dad's gonna help me, we just need to know the procedure, if you dont mind

OK Give ma a day or so to get the write up all done.

Here is what it says in VADIS:

Power brake booster, replacing
Preparation

Disconnect the battery lead
See Note when disconnecting/connecting the battery lead .

Removal

Preparations for removing the power brake booster
Switch off the ignition.
Remove the cross member

(On 5 cylinder engines). Remove the screws and nuts from the engine mounting. Lift out the cross member.
Remove the air cleaner (ACL) housing

Remove the plastic cap and the cable holder

Remove the integrated relay / fusebox

Preparations for removing the ABS unit
Clean the brake pipes terminals at the master cylinder and ABS unit.
Place paper under the master cylinder to avoid brake fluid spillage.
Remove all the brake pipes from the master cylinder and the ABS unit.
Plug the master cylinder socket for the brake pipes.

Remove the ABS unit and bracket from the side member
The unit is secured with three screws.
Note! Store the ABS unit in such a way that no dirt can get into the pipe couplings.

Preparations for removing the master cylinder
Note! On cars with 6–cylinder engines: Disconnect the connectors from the master cylinder.
Mark up a connector.
Disconnect the connectors on the power brake booster.
Note! If the car has hydraulic clutch: Block the hose to the clutch cylinder. Use hose pliers.

Remove the master cylinder
Avoid brake fluid spillage when removing.
Note! Ensure that the gasket between the power brake booster and the master cylinder stays in place on the master cylinder.
Remove the soundproofing panel and the power brake booster

Transfer the components to the new power brake booster
Transfer:
-the pedal position sensor. See: Pedal position sensor, replacing
-the check valve
-the terminal for the check valve.

Installation

Install the power brake booster
Install the push rod for the power brake booster and the retaining clip on the brake pedal
Tighten the power brake booster. Tighten to 25 Nm.
Install the soundproofing panel.

Install the master cylinder
Note! Check that the gasket is in place on the master cylinder.
Tighten the nuts. Tighten to 25 Nm.
Install the vacuum hose on the check valve for the power brake booster.

Install the connectors and vacuum hose
Install:
-the connectors on the master cylinder and the power brake booster
-the vacuum hose on the check valve.
Note! The vacuum hose must be behind the bracket for the ABS hydraulic modulator.
Note! There are 2 connectors for the master cylinder on cars with 6–cylinder engines. One is for the pressure switch and the other is for the power brake booster.

Install the ABS unit and the bracket
Install the bracket in the side member. Tighten to 10 Nm.
Install the brake pipes in the master cylinder and in the hydraulic modulator
Tighten to 17 Nm
Install the integrated relay / fusebox and the connector for the ABS unit
Install the air cleaner (ACL) housing
Install the cross member
Fill and bleed the brake system

Checking the power brake booster

Depress the brake pedal several times until it feels stiff.
Hold the pedal down. Start the engine. The pedal should travel and feel softer.
Release the brake. switch off the engine. Wait 1 minute. Then depress the pedal. The pedal should still feel soft but should become stiffer when it is depressed several times.
There should be no leakage between the vacuum hose and the terminal at the power brake booster.
There should not be any leakage between the master cylinder and the power brake booster.
Check that the stop lamp functions.
If the stop lamp switch has been modified or changed after installation of the master cylinder and power brake booster it must be readjusted.

Hope that helps, I am sure tech could write a more simplified write up.

Here is how I do it.
Brake Booster replacement:

First start by Disconnecting the Battery.

Then open the hood and remove the Upper torque mount cross member.

Next remove the Air filter housing.

The remove the Big Cover over the Relay/fuse panel under the hood.
Once the cover is off remove the 13mm nut for the Positive cable.

Then remove the 2 screws securing the Relay box into place.(one of the screws is under where the positive cable just came off)
Unplug the one harness from the box and move the box to the side.

Then reach under and unplug the ABS module. There is 2 plugs. One you have to push a little tab and fold the cover back to release the plug. The other is 2 push tabs then pull.

Ok here is where it will get a little tricky. Look where the ABS pump motor assembly bolts to the body. There is 3 10mm bolts remove them and make sure the pump motor is loose.(No need to disconnect the lines)
Remove the 2 screws holding the Master Cylinder to the booster.
Unplug the sensor in the booster. Remove the Line and Valve from inside the booster.

That should be about it from outside till the booster is loose.

Inside the car:

Remove the Lower dash panel on the drivers side.
Then remove the clip holding the brake pedal to the booster. Either slide the Pin out or slide the Arm off.(Forget which it has). Then remove the 4 13mm screws holding the Booster to the Firewall.

Now go back outside:

Then slide the Master cylinder off of the Booster and kind of pull and move to the side.
Might require Carefully bending some of the lines. Then slide the Booster out.(Most of the times it takes some work to get it slid out. It might take some time to slide it out just take your time.

Then install in reverse order.

It will take a little time to do. About 1/2 a day at home with Hand tools.

The part should be hear on wednessday, It costed me 225$ and it comes with a lifetime guarantee... question, I was taking a closer look at it today, on the inside Behind the brake pedal is a squishy grayish rigged shaped thing, that when you push the brake pedal it goes down in sequence with it. I can hear the noise "hissing" and feel a little air... it gets louder if i move it a little(that gray squishy thing).. Is this still the booster?

That comes with the new booster. Yes that is part of the booster.

What does the booster do exactly? How would it exactly affect me?

It would be like stopping the car with REALLY hard brakes.

Go into a parking lot and go about 15-20 MPH and turn the car off and push the brake pedal wasy till it gets hard then try to stop. Thats what it would feel like.

Make sure you try this in a Safe Area

The booster acts as a force multiplier on the brake fluid. Since force on a liquid expands the same in all directions, your foot can only produce so much force on the liquid to apply the brakes. The booster will provide a much higher multiplication of force with the help of a diaphram.

Tech I know its hard to say but Ive been having the hissing on my s80 for a few months now is this something that should be change immediately or am I ok? Does it go out completely or wear down?

I would change as soon as you can.