Q&A for How to Replace a Master Cylinder

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  • Question
    After bleeding my brakes, the pedal is not having pressure, what should I do?
    wikiHow Staff Editor
    Staff Answer
    This answer was written by one of our trained team of researchers who validated it for accuracy and comprehensiveness.
    wikiHow Staff Editor
    Staff Answer
    Try bleeding the brakes again. This is a sign of air in the system or a bad master cylinder.
  • Question
    What do I need to do to a master cylinder before installing it on a car?
    Community Answer
    The new master comes with two clear rubber hoses and two plastic nipples that screw into the holes where you would put the brake lines. Screw and tighten the nipples. Fill the master cylinder with fluid. Put one rubber hose in each chamber of the master, and then connect them to the nipples. You need to place the master in a vise, in the round part in the back of cylinder between the two holes where it bolts on. Use a Phillips screwdriver and pump it -- it will be really hard to push, but push until you no longer see bubbles in the clear hoses. Make sure the hoses stay in the fluid -- you may need to have someone hold them while you pump.
  • Question
    What is wrong with my brakes if the brake light is on?
    Community Answer
    If you put you foot behind the brake pedal and pull up and the light goes off, look up in the pedal and see if the electrical switch is loose or broken. If not, you need to have your breaks checked by a mechanic. Make sure it's not your ABS light.
  • Question
    Should I take out the master cylinder after bleeding the brakes?
    R-Dixie- Normus
    Community Answer
    It doesn't matter, because you're still going to have to bleed them when you replace the master cylinder. Once the lines are disconnected, you've let air into your brake system. Air in the brake system is not good as it can seize up the brakes. Make sure you bleed the brakes AFTER you install the new master cylinder, though.
  • Question
    How do I remove air from the clutch slave cylinder?
    Community Answer
    One way is called gravity bleeding: loosen the bleeder on the slave cylinder, making sure the fluid is full. Open bleeder until fluid gets low in the reservoir. Keep filling it up with the bleeder open and the cap off the reservoir.
  • Question
    How difficult is it to replace the front brake shoes and master cylinder on a 2005 Camry if I have little auto knowledge?
    R-Dixie- Normus
    Community Answer
    It is not very hard. If you're able to locate a few bolts, and piece a puzzle together, changing brake shoes is a piece of cake just as much as the master cylinder. The only challenge for a newbie would be using the tools that are required.
  • Question
    I had my master cylinder replaced, but my brake pedal keeps going down. What is wrong?
    Community Answer
    Try rebleeding the complete brake system, brand new fluid! Be certain you are using the correct "dot" type brake fluid. If once completed the same symptoms occur, you may have a seepage or leak in the system or even a faulty master. Or you may have to power bleed your system. Also be sure the master is not a stage 4 type as this kind requires a special bleeding technique. Be sure your power brake booster tank and fittings are not leaking out or within.
  • Question
    How do I adjust a clutch master cylinder?
    Community Answer
    Drain and clean it then refill with new clutch fluid. Bleed the cylinder like brakes and check for a stiffer pedal. If still not fully disengaging, look under dash board at the clutch pedal that nothing is restricting the full travel (carpet or floot mat).
  • Question
    How can I replace the master cylinder on a 1949 style line Chevy Deluxe?
    Community Answer
    Use plenty of releasing fluid on all attached fittings daily for a week. Carefully release fittings a little at a time. A tight nut can be freed by heating the nut very carefully and rubbing a wax candle on exposed threads. Try again. If the nut moves a few threads, wind back and try the candle trick again so more wax wicks further along the threads. When all attachments are undone, remove the unit. I don't know if that model used cable brakes, so doublecheck.
  • Question
    How do I remove the brake reservoir?
    Community Answer
    Pull it up with your hands, it pops out. Be careful not to get fluid in your eyes.
  • Question
    Should there be brake fluid in my brake booster?
    Community Answer
    NO! If there is fluid in the booster, it means the seal on the master cylinder is damaged/worn. Both need to be replaced.
  • Question
    How do I find the master cylinder on my vehicle? Does it need to be removed from under the chassis?
    Community Answer
    Your master cylinder is under the reservoir that you add brake fluid to. It is bolted into the brake booster on the fire wall.
  • Question
    What do I do if brake fluid spits out from the brake line?
    Community Answer
    If you are bleeding the brakes and fluid is spitting out rather than running out, it is letting out air that was trapped in the line. This is good. Repeat the process while someone depress the brake pedal and hold it while you open the bleeder valve. Close the bleeder valve as soon as fluid is streaming out and not spitting. Do not release the brake pedal until the bleeder is tightened so it doesn't draw air back up into the line. Repeat a couple times more to make sure all air is out of the line. Repeat the procedure on all remaining wheels.
  • Question
    What are the signs of a bad master cylinder?
    Drew Hawkins1
    Community Answer
    The brake master cylinder is an important component of your vehicle's brake system. If it fails, your vehicle's braking ability will be weakened or destroyed. Luckily, there are a few signs you can look for to determine if your master cylinder is bad. If you notice your brake pedal is behaving abnormally or your brake warning light comes on, it's a big sign that it could be the cylinder. You may also have low brake fluid levels, or contaminated brake fluid. Additionally, you can check for leaks to see if your brake fluid is draining out of your vehicle, which is a sign that you need to replace the master cylinder. Park on level ground, look under your hood, start up the engine, and check for leaks in the engine or beneath the vehicle. If you suspect that your cylinder is bad, take your vehicle to a licensed mechanic to have it checked out and replaced, if needed.
  • Question
    Can you replace master cylinder without bleeding brakes?
    Drew Hawkins1
    Community Answer
    No, you really need to drain the brake fluid. Because you need to disconnect the brake lines, removing the fluid is the best way to prevent spills. Luckily, it's not that hard to do. Start by removing the cap, and then insert a siphon or a turkey baster into the reservoir. Remove all of the brake fluid and dispose or recycle it in accordance with local laws and regulations. Contact your local agency that deals with household hazardous wastes for any needed information. Don't just throw out the fluid into the garbage. It could create a nasty mess and may actually be illegal in some locations.
  • Question
    Can you drive with a bad brake master cylinder?
    Drew Hawkins1
    Community Answer
    No, you really shouldn't. You could get into a potentially dangerous accident. The brake master cylinder is a key component of a vehicle's brake system. If it fails, you may have difficulty braking, or you may not be able to brake at all. If you notice your brake pedal is behaving strangely, or it takes longer than usual for your vehicle to slow down, it could mean your brake master cylinder is having problems. Take your vehicle to a mechanic and stay off the roads. If your brakes give out entirely, you won't be able to stop.
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