Boston Mobile Mechanics / Auto Repair Services / Mobile Car Repairs

Brake Master Cylinder Replacement

Brake Rotors

Replacement

What is a Brake Rotor/Disc?

A brake rotor is a smooth metal disc attached to the wheel hub. Most new cars (1999 and above) come with rotors at each wheel. Older cars may have drums instead of rotors at the rear wheels .

Brake rotors play an important part in the braking system. It is the friction between brake pads and rotors that cause the car to slow down and stop. As the rotors wear out (become thin or warped), they are unable to dissipate the heat caused by the braking system. This will cause the brake fluid to boil and reduce the effectiveness of the brake system significantly.

Brake rotors are replaced in pairs. Keep in mind that if you choose front brake rotors, both front wheels should get new rotors. The service should come with new brake pads. Unless brake pads were replaced recently, pads must be replaced while replacing the rotors.

It is a good idea to get the thickness of brake rotors measured annually. The mechanic should measure the rotor thickness every time the brake pads are replaced. Brake rotors usually last twice as long as brake pads. This means that the rotors need to be replaced, every other brake service. Driving the car with worn-out brake pads for too long will destroy the rotors.

Brake rotors or discs must be replaced if there is a vibration or pulsation when applying brakes; if a blue discoloration of rotor surface is seen, and if there are already grooves or hot spots in the rotors.

What is a Brake Master Cylinder?

The brake master cylinder contains the brake fluid and is connected to the brakes, through the brake pipes and hoses. Brake fluid flows from the master cylinder to the braking unit at each wheel, creating friction to slow down and/or stop the car. The cylinder has internal and external seals that can wear out over time.

When external seals wore out, they leak brake fluid, reducing the amount of fluid in the car and causing the brakes to malfunction. Worn external seals leak the fluid into the brake booster - and destroy it. The booster is essential for the proper functioning of the brakes, so if brake fluid has leaked into it, replacement is required.

When internal seals wore out, the brake fluid will continue to circulate inside, instead of being directed to the brakes. This weakens the brake performance. The brake pedal will feel soft when you apply the brakes. The pedal will go all the way to the floor - without significantly slowing or stopping the car.

After replacing the brake master cylinder, the mechanic should flush the old brake fluid out and replace it with a new brake fluid.

What is a Radiator Fan Motor?

The radiator fan motor powers the cooling fan, which keeps the engine from overheating. The fan is located in the engine compartment, at the front or rear of the radiator. The engine of a vehicle is constantly burning fuel and gets hot. The car’s cooling system is responsible for carrying heat away to the outside air. The fan cools the coolant as it passes through the radiator. The coolant flows through the entire engine and is responsible for absorbing the extra heat and thereby preventing the engine from overheating. The fan blows the air from the outside and passes it through the radiator. If the radiator fan motor and the fan stop working, the coolant will remain hot and cause the engine to overheat.

The radiator/cooling fan motor is an electrical motor that resides in a high temperature environment. At some point over time, it will fail. If the engine overheats (check the temperature gauge in the dashboard), and the fan is working, the cooling system should be inspected immediately.

The mechanic should always check the coolant and fill, if needed. The coolant must be replaced based on the service maintenance schedule. It is a good practice to change the coolant every 25,000 -40,000 miles.

If a defective radiator fan motor is left unchecked, the car will overheat and effectively become undriveable.

What is a Radiator?

The radiator performs a critical function - it keeps the engine from overheating. While running, the engine produces heat. The engine coolant flowing through the system absorbs and removes extra heat from the engine. It then passes through the radiator where it cools off and is later circulated back to the engine - to absorb heat again.

A radiator has two tanks that are connected to each other through aluminum or brass tubes. When the coolant passes through these tubes, the radiator cooling fan blows air across the radiator to lower the temperature of the coolant. The tank is usually made of plastic, and it is common for it to crack and start leaking coolant. If the tank or the tubes crack, coolant will leak, the vehicle will overheat and could cause severe engine damage. Also, radiators tend to clog over time. When this occurs, not enough coolant flows through the radiator leading to heat build-up, causing the engine to overheat.

What the mechanic will do is remove and replace the old radiator, fill the new radiator with proper mixture of 50/50 coolant and, check the radiator for leaks. The coolant should be replaced at regular intervals, based on the service maintenance schedule provided by the manufacturer. It is a good practice to change the coolant every 25,000-40,000 miles. Replacing the coolant will ensure it is free of contaminants such as rust or scale that can block it from flowing through the radiator and engine. Given the high engine temperatures, it is inevitable that the tanks in the radiator will eventually crack.

The thermostat should also be replaced when replacing the radiator as well as any necessary radiator hoses. The system should also be flushed out of all old coolant to remove any contamination. The common symptoms that indicate the need to replace the radiator include - the car is overheating and, the coolant is leaking.