How To Bleed The Master Cylinder And Brake System

your master cylinder is the heart of your vehicle's braking system when you press your brake pedal it distributes brake fluid through hydraulic lines to four wheels of your car anytime a hydraulic braking component is replaced air will into the system that can cause a spongy pedal and reduced braking performance to prevent this reduction in breaking the process of bleeding the brake system must be performed in this video we'll discuss the methods for bleeding the brake system as well as **** bleeding the master cylinder since we'll be working under the hood it's important to observe a basic safety precautions set the parking brake and be sure automatic transmissions are in park and manual transmissions are neutral to avoid burns allow your vehicle to cool before doing any type of repair don't wear loose clothing or jewelry that could get caught in moving parts or might bridge electrical connections and finally always wear proper eye protection before you begin work be sure the vehicle is parked in a level area and that the wheels are charged to prevent any unintentional movement when bleeding the brake system it's important that you use the correct brake fluid always refer to your owner's manual for the type of brake fluid that should be used in your vehicle dot three and dot four on the most commonly used types of brake fluid dot five in dot five point one or silicone based fluid which should be used only to fill non Abia systems that have never been previously feel with glycol based dot three and dot for fluid typically dot five in dot five point one fluids aren't recommended for normal automotive use once again always check the owner's manual to see which flew with the manufacturer recommends for your vehicle there are four methods for bleeding to brake system they are manual pressure vacuum and gravity regardless of the type of bleeding that is performed make sure to keep the master cylinder full of brake fluid during the entire process and work from the far this wheel from the master cylinder first to the closest last when bleeding a wheel that has disk brakes attach a clear to to the bleeder screw on the brake caliper for drum brakes attach the clear to to the bleeder screw on the wheel cylinder and then place the other end of the hose into a container first we'll discuss the manual method manual bleeding requires an assistant inside the vehicle to apply and release the brakes your assistant pump the brake pedal a few times and then hold firm pressure with pressure being applied to the brakes by your system open the bleeder screw as brake fluid flows through the clear to the pedal will begin to fall towards the floor close the leader of al before the pedal reaches the floor and tell your assistant to release the pedal repeat this procedure until a clean a steady stream of brake fluid with no air bubbles as observed repeat this process for the remaining bleeder screws remembering to keep a close eye on the brake fluid level in the master cylinder next let's talk about vacuum bleeding vacuum bleeding is accomplished using a vacuum pump that you can purchase at your local AutoZone attach the pump to the bleeder screw with a clear hose open the bleeder screw and start applying vacuum with the pop once you see a steady stream of clean brake fluid close the bleeder screw and repeat this process for the remaining bleeder screws remembering to keep a close eye on the brake fluid level in the master cylinder the gravity method is the most basic method of brake bleeding and can be done by one person as the master cylinder is at the highest point in the car all bleeder screws can be open at the same time and gravity will pull the fluid slowly through the system when brake fluid is flowing out of the bleeder screw free of bubbles calls the bleeder screw begin this process working with the bleeder screw farthest from the master cylinder first and continue to work to the bleeder screw closest closing that one last keeping an eye on the brake fluid level and the master cylinder the pressure beating met they require special equipment that the typical do it yourselfer doesn't have available it's a simple process that doesn't require an assistant but instead uses a specialized tank commonly referred to as a bleeder ball the bleeder ball feats brake fluid to the master cylinder under pressure keeping in full during the bleeding process while brake fluid is pushed through the system at ten to fifteen PSI bleeder screws are opened one at a time so that air can be forced out of the system when fluid coming out of the open bleeder screw is clean and free of bubbles the bleeder is closed and the process is repeated for the remaining bleeder screws now will discuss the bleeding the master cylinder off the vehicle commonly called the bench bleeding many master cylinders are required to be **** split to avoid air being introduced into the braking system which can reduce braking performance when you're better bleeding a master cylinder it's best to securely fastened the master cylinder in a vise parallel to the floor if you're purchasing a master cylinder you'll find that most come with the bleeding kid but if you're removing and reinstalling a master cylinder you'll need to have bar fittings and clear tubing to complete this job first screw the barb fittings into the ports on the side of the master cylinder then insert a clear rubber tube onto each of the fittings and place the other in into the master cylinder wrestle for making sure the hoses are held securely in place so that they don't slip out if the master cylinder has a proportioning valve attached and you're replacing the master cylinder the proportioning valve must be transferred to the new master cylinder prior to bench bleeding for proportioning valve equipped master cylinders install the barb fittings and holes into the op reports of the master cylinder and plug the lower ports of the proportioning valve once the barb fittings and housing are in place and the reservoirs full of fresh brake fluid use either a wooden dowel a blunt metal rod or a large Philips screwdriver to compress the master cylinder plunger with slow deep strokes until there are no bubbles coming to the clear tubing take note that in some master cylinders it may be necessary to apply and released the piston up to seventy times to expel all the year keeping the hoses and fittings used to believe the master cylinder in place removed from the vice and install on the vehicle for master cylinders without a proportioning valve once a secure on the vehicle the barb fittings and tubes can be removed and the brake lights can be attached if the master cylinder is equipped with a proportioning valve had the assistant press down on the pedal and open to reports upper and lower one full turn then retired and have the assistant release the pedal and do the same for the front two ports this step should be repeated at least one more time to insure the air is removed between the lines and the master cylinder after the master cylinder has been best bled and installed on the vehicle fill it with brake fluid and continue with bleeding the brakes at each wheel to finish the process of bleeding the brake system if you choose to try any of these methods to bleed your master cylinder and brake system you can find all the parts products and expert advice you need at your local AutoZone parts are just part of what we do get in the zone and thanks for watching