Your master cylinder with bleed kit. Fresh brake fluid. A workbench or table with a fixed vise. If you have neither of these, it will be more cost-effective to go to the next method, which does not require a specialized workspace. A wooden or plastic dowel. Make sure this is strong, because you don’t want it to snap while you’re working.
If the new part didn’t come with a reservoir, be sure to remove the one from the old part.
Hold the master cylinder by its flared mount, and make sure it is level. This way, the air will leave properly, and it will fill with brake fluid evenly without gaps. It needs to be firmly secured, but not so tight you crush or damage cast aluminum parts. Make sure the plastic fittings are not crushed or blocked when putting the cylinder in the vise. If your table does not have a pre-installed vise clamp, you can buy a separate vise that clamps on to the table if you do not have one pre-installed. If you like the appearance of this table, it might be best not to use it, as vise clamps leave a mark on wood or metal. If you have no other usable tables, wedge a rag in between the vise clamps to avoid leaving a mark. This may not work, so proceed at your own risk.
The inserts will be threaded on one side, and the other will be a smooth adapter for taking the hose. Check the color of your hose, too. If you have opaque hose, you might want to replace it with clear hose, because then you can see the air bubbles passing through the fluid more easily. You can also opt not to use the bleeding kit, as it isn’t necessary. However, this guide will assume that you are using the bleeding kit.
Install these into the bosses (the threaded holes) without cross threading them. Make sure they are finger tight.
Consider attaching the hoses to the container in some way. Once you begin pumping, they will begin flailing about and spray blake fluid everywhere if they are not anchored down in some way. An old coffee can works especially well for this, as does any cylindrical container with a wide, flared opening.
You should only put clean brake fluid that is less than two years old into the reservoir. Make sure it’s in between the “max” and “min” marks and covers the ends of the hoses. Brake fluid is very hygroscopic, which means it absorbs moisture and will degrade, and this damages the seals. Do not reuse brake fluid
Don’t bottom out the piston, otherwise this might allow the entrance of air. You have to pinch the rubber hoses closed each and every time you release pressure on the cylinder.
This also prevents air from entering the master cylinder by not providing a vacuum for it to fill.
You will know you’re finished pumping when there are no more air bubbles rising in the reservoir or present in the container of spent brake fluid.
When installing it in the vehicle, keep it level and remove the bleeding kit as you install the lines. If you did this right, you shouldn’t need to bleed the entire system, but you may want to to flush the system of old fluid. [5] X Research source
If you’ve done it right, the brakes should feel clean and crisp when you pump them. If you’ve done it wrong, the brakes will feel “squishy” when you pump them from your car, indicating there is still air in the master cylinder. If the break pedal feels soft after installing the master cylinder, follow the instructions for the method on bleeding the master cylinder from the car, or this guide on bleeding brake lines.
A brake bleed screwdriver or wrench. You will have to loosen the screws that hold the hoses in place in order to bleed the master cylinder. Pliers. You will need these to pinch the hose attached to your master cylinder in between pumps WD-40 or other water-displacing solvent. Your brake bleed screw may be caked with oil or other contaminants and be difficult to unscrew. You’ll use the WD-40 to remove this material and allow yourself to loosen the screw. A helper. He or she will pump your brakes while you fiddle with the hoses and screws underneath your car.
Immobilize the car by blocking the wheels, and make sure it won’t roll by parking it on a flat surface. [7] X Research source
Consider attaching the hoses to the container in some way. Once you begin pumping, they will begin flailing about and spray blake fluid everywhere if they are not anchored down in some way. An old coffee can works especially well for this, as does any cylindrical container with a wide, flared opening.
You’re trying to bleed your master cylinder, and not your brakes, so you don’t want to affect the latter by messing with the former. Likely, brake fluid will instantly fly out. This is why you want to have a container attached. Before your helper releases the pedal, make sure you have the hoses back on.
This is also why it is important to have a container or jar, because without collecting the fluid, you will have no idea whether there is fluid in the brakes or not.
Don’t forget to continue topping up the master cylinder with brake fluid. Otherwise, you may introduce air into it and have to begin again.
