Changing Master Cylinder Brake Repairs how to Fix Master Cylinder Brake Problems
All braking problems should be treated very seriously, especially when there is any indication that your brakes are not operating normally. In the event that your brake light warning light comes on or if your brake pedal doesn't spring back up after applying pressure, it might be time to consider replacing the brake master cylinder! Other less common symptoms are, leaking around the master cylinder seals, or pulsations when applying pressure to the brakes.
One important word of caution: Never continue driving a vehicle when a mechanical brake issue is detected, regardless of the severity. The most simple brake problem, can quickly escalate, which endangers you and the passengers within your care.
WHAT IS THE MASTER CYLINDER?
Now, to understand the function of the master cylinder we first must understand that all brakes work on the principle of pressure and friction. The master cylinder basically is a two-stage system that creates the needed pressure within the brake lines to exert the necessary force to cause the brake system to react.
HOW DO I KNOW THE MASTER CYLINDER NEEDS TO BE REPLACED?
Simple indications usually start on the dashboard console, which result in the illumination of the brake warning light. Check to see if your parking brake is still engaged, and if not inspecting the brake fluid level will rule out simple problems.Again if brake pressure is absent, and the pedal remains stuck to the floor, the master cylinder is a prime culprit. Pooling of brake fluid, or leaking around the master cylinder reservoir or the master cylinder itself is a clear indication a replacement is needed.
How do I change the master cylinder?
Step one: Locate the master cylinder, which typically can be found under the hood, closest to the front of the car. The master cylinder will be attached to a small plastic tank that has a screw top lid.
Step two: Once you've located the master cylinder and fluid reservoir, you must drain it properly before removing the defective unit. There is a suction tool that can be used, but for the DIY backyard mechanic a simple turkey baster works great to suck out as much of the brake fluid as possible to avoid a big mess during the removal process.
Step three: Locate the brake fluid level sensor, which appears to be a small wire harness attached to the bottom of the brake fluid reservoir. Take care when removing the harness since the clips must be depressed in order for it to be properly removed.Step four: Next you will have to disconnect all the brake lines that are connected directly to the master cylinder. Although there is a specific wrench designed to be used to remove the brake lines, called a "line wrench", you still can take the DIY backyard mechanic route and go with channel locks or a pair of vice grips. My advice is to go with the proper tool, since it differs from other wrenches due to the five separate points opposed to a standard wrench with only two. The cost is nominal and there is less chance of damaging the fittings that connect the brake lines to the master cylinder. The typical setup will have four individual lines connected.
TIP:Place an old rag underneath the master cylinder before disconnecting the brake lines from the master cylinder to catch excess spillage. Secondary, you can use the rag while removing the master cylinder, which commonly will have some excess fluid drainage.
Step five: The last step is to remove the master cylinder assembly. Locate two fastening bolts that harness the master cylinder to the car. It is best to use a socket wrench, preferably one with an extension piece since it can some times be a tight fit. With the bolts removed you should now be able to remove the master cylinder. It may be a bit stiff so apply a little pressure, or tap it with a hammer or screwdriver to knock it loose.
Now that you are basking in your mechanical prowess, you can begin to reverse the above steps with your new master cylinder. It is best to discard the old brake fluid and use some fresh fluid. Ensure that the mounting bolts are firmly snug, and do not over tighten the brake line fittings to prevent stripping.
Refer to your manual or the specifications indicated on the reservoir cap for the brake fluid type. Typically you will use either DOT3 or DOT4, but if all else fails check the owner's manual for manufacturer's recommendations.
The last and final step, which is frequently neglected, is ensuring the brake lines are properly bled. Bleeding the brakes ensures that there is no air in the lines, and pressure is distributed evenly. Simply uncap all the bleeder caps, which are connected to the brake calliper or wheel cylinder. Once all caps are removed, have someone step firmly on the brakes until the pedal is on the floor. With the brake pedal still firmly pressed, you can now wipe excess fluid and cap the bleeder.
Once you have completed all these steps, it is important that you pump the brakes a few times to regain brake pressure before driving. The first application will feel as though the pedal sinks to the floor, this is normal and it will regain elasticity after a few more pumps.
There, that was pretty easy! Well on a scale of 1 to 10 for difficulty, I would probably rate this task a four. Honestly, there are several minor maintenance jobs like replacing the master cylinder, but for those who cringe at the sight of tools and are not comfortable with the idea of getting their hands a little dirty, it is best to leave it for a licensed mechanic instead.
