How to Perform a Brake Fluid Reservoir Replacement (+Costs)

The brake fluid reservoir stores your brake fluid, prevents it from getting contaminated, and accommodates natural brake fluid level changes as your brake pads wear down over time.

When it fails — it’s not just an inconvenience — it’s a potential safety risk.

A low brake fluid level due to a faulty reservoir can lead to serious braking issues, making a replacement non-negotiable.

Want to learn about brake fluid reservoir replacement?
To get your brake system back in working condition, we’ll cover how to replace the brake fluid reservoir and how much it’ll cost.

This Article Contains:

How Does a Mechanic Replace the Brake Fluid Reservoir?
How Much Does a Brake Fluid Reservoir Replacement Cost?
3 FAQs on Brake Fluid Reservoir Replacement

How Does a Mechanic Replace the Brake Fluid Reservoir?

Replacing your brake fluid reservoir is a relatively complex task that you should leave to your mechanic.

Some tools and materials they’ll use include:

Gloves
Safety goggles
Wrench or socket
Screwdriver
Brake cleaner
Clean rags
A container to keep the old brake fluid

Now, let’s look at how the process works.

A. Old Brake Fluid Reservoir Removal

Here’s how they’ll perform the removal of the old brake fluid reservoir:

Step 1: Access the Engine Compartment

Your mechanic will first need access to the engine compartment or engine bay. They’ll open the car’s hood and secure it to gain access.

Step 2: Locate the Brake Master Cylinder

They’ll locate the brake master cylinder, usually at the back of the car engine compartment, on the brake pedal side.

There will be two to four metal tubes attached to the brake master cylinder (known as a brake line — with a hose attached to the end). Each brake line carries brake fluid to the brake calipers at the car wheels. The flexible hose transfers the fluid from the rigid line to the calipers.

Step 3: Empty the Brake Fluid Reservoir

Next, your mechanic will unscrew the reservoir cap and drain the old fluid into a container. A simple tool like a turkey baster or a vacuum syringe will work to extract the old fluid.

They’ll also detach the fluid level sensor.

Step 4: Secure the Brake Master Cylinder and Remove the Roll Pins

They’ll secure the master cylinder body with a vise to keep it from moving while the old reservoir is detached. Then, they’ll remove the roll pins that hold the brake fluid reservoir to the master cylinder.

Step 5: Detach the Brake Fluid Reservoir from the Master Cylinder

Your mechanic will insert a pry tool (like a flat-headed screwdriver) between the old reservoir and master cylinder to loosen it. Once the brake reservoir is free, they’ll remove the rubber grommet that acts as a seal between it and the master cylinder.

They’ll then proceed to install the new fluid reservoir.

B. New Brake Fluid Reservoir Installation

Here are the steps a mechanic follows to install a new brake fluid reservoir:

Step 1: Install New Grommets in the Brake Master Cylinder

Your mechanic will lubricate the new grommets with fresh brake fluid and install them in the master cylinder body. They’ll do this by hand (instead of with a tool) to minimize possible damage to the grommet that could lead to a brake fluid leak.

Step 2: Install the New Reservoir

They’ll seat the new fluid reservoir in the grommets and press down to connect it with the brake master cylinder.

Step 3: Reinstall the Roll Pins

Your mechanic will reinstall the roll pins that secure the new reservoir to the master cylinder body. They’ll also reinstall the fluid level sensor.

Step 4: Fill the Reservoir with Fresh Brake Fluid

They’ll fill the new brake reservoir with fresh fluid to the correct fluid level. Brake fluid starts degrading fast, so they must use fresh fluid from a new container.

Step 5: Clean Up

The mechanic will remove any excess fluid using a rag and apply the brake cleaner to clean the area around the master cylinder. They’d properly dispose of the old brake fluid as it qualifies as hazardous waste.

Curious about how much a mechanic charges for this auto repair procedure?
Let’s take a look.

How Much Does a Brake Fluid Reservoir Replacement Cost?

On average, you can expect to spend $210 to $300 for a brake fluid reservoir replacement. This includes:

Parts: $110 to $150
Labor: $100 to $150

The price will vary depending on whether you purchase a part from the original equipment manufacturer (OEM) or aftermarket parts (e.g., Dorman products). OEMs tend to be more expensive. The final cost will also depend on your car’s model. For example, parts for a luxury brand like BMW may be more expensive than for a Toyota or Honda.

Now that we’ve covered the basics of brake fluid reservoir replacement, let’s answer any other questions you may have.

3 FAQs on Brake Fluid Reservoir Replacement

Here’s everything else you should know about brake fluid reservoirs:

1. Is It Worth Replacing the Brake Fluid Reservoir?

Yes, replacing the brake fluid reservoir is essential for the proper function of your brake system. A damaged brake fluid reservoir will lead to leaks and contaminated brake fluid, both of which affect the hydraulic system.

Adequate hydraulic pressure between the brake pads and rotors creates friction necessary to stop the vehicle when you press the brake pedal. A low brake fluid level will result in an inability to properly engage the brake pads on the rotors due to reduced pressure.

On the other hand, hydraulic fluid contaminated with moisture or dirt will have a decreased boiling point which can also reduce vehicle braking performance.

NOTE: Sometimes, a damaged reservoir cap can also fail to seal out moisture from the brake fluid, which can affect braking.

2. Can You Replace the Brake Fluid Reservoir Yourself?

No, you shouldn’t attempt a DIY brake fluid reservoir replacement and let a professional mechanic handle it.

Here’s why:
Firstly, a brake fluid reservoir replacement may involve some contact with brake fluid, which can be corrosive and toxic. The brakes may also require bleeding to eliminate possible air bubbles after a reservoir replacement, which requires a bleeder kit.

Secondly, the replacement is crucial for the proper functioning of the braking system. Any misstep during the installation can compromise the hydraulic system and put you in danger on the road.

3. Do You Have to Replace the Master Cylinder Along with the Fluid Reservoir?

Most of the time, no.

The brake reservoir sits on a separable grommet (or two, depending on the master cylinder type) fitted to the top of the brake master cylinder. This allows a professional mechanic to replace the fluid reservoir without needing a new brake master cylinder.

However, you may need a new brake master cylinder if these parts are connected.

Replace Your Brake Fluid Reservoir with AutoNation Mobile Service

A damaged brake fluid reservoir can lead to a brake fluid leak, which will reduce your vehicle’s braking ability. The increased stopping distance can put you in danger on the road, so replace your reservoir ASAP.

Worried about driving to the mechanic with a dodgy braking system?

AutoNation Mobile Service mechanics will replace your brake fluid reservoir right from your driveway. We’re available seven days a week and offer a 12-month,12,000-mile warranty on all repairs.