The process of removing air bubbles from the braking system of automobiles is called bleeding brakes. It is often recommended as part of a comprehensive car maintenance regimen. Air bubbles are detrimental to the braking system. Air bubbles create an unwanted insulation layer within the hydraulic system. This is also called softening of brakes. As a result, the braking pedal develops a distinct, spongy feel. This creates a lag in the time taken for the car to stop when brakes are applied.
Bleeding Brake Techniques
Brakes can be bled in different ways. The two main methods are:
- Vacuum or pressure pumping (industrial method)
- Pump and hold method (household method)
Vacuum and pressure pumping require expensive, industrial instruments that are conventionally not found in household garages. The pump and hold method is recommended for household bleeding of brakes. This is essentially a two-man job. One person pushes upon the brake pedal while the other tightens the exposed, braking valves. The braking system of used cars often develops bleeding valves. These loose valves act as entry points for air bubbles. Bleeding valves can be corrected by tightening the valves’ calipers with a wrench. This is the simplest way of improving the brake pedal‘s action. An essential component of this method is replacing the old brake fluid. This is also the most commonly ignored aspect of bleeding brakes.
Brake Fluid Replacement
Replacing the brake fluid is known to make the entire braking system sharper. The reason lies in the higher boiling point of the fresh brake fluid. With constant use, brake fluid starts to absorb more moisture by trapping more air bubbles. This increases the amount of air seeping into the hydraulic system of the car. This causes another problem. The increased moisture content causes the boiling point of the brake fluid to drop. Due to a lower boiling point, the moisture within the brake fluid evaporates quickly, traveling within the car’s engine. This causes internal corrosion of the engine assembly. Internal corrosion can cause irreparable damage to the master cylinder. Therefore, frequent brake bleeding is recommended for making the braking more responsive and for the overall health of your car.
Brake Bleeding Procedure Basics
Start at the farthest wheel. This means you should start with bleeding the brakes at the right rear end. This should be followed with bleeding brakes at the left rear, right front, and then left front. However, if you are bleeding brakes of a car with four-wheel drive coupled with ABS, this rule can be ignored.
Brake Bleeding: Cost Considerations
Most car manufacturers specify the frequency with which a car needs to be brake bled. If such information is not available, bleed the brakes, every two years. You need to invest in buying wrenches that perfectly wrap around the hex of the bleeder valves and some brake fluid. You don’t need too much of the brake fluid. A single session of brake bleeding usually requires about ½ to 1 liter of branded brake fluid. You save on expensive repairs that would be incurred if any component of the brakes corrodes or the braking system needs extensive overhauling.