When it comes to your car's brakes, you simply can't leave things to chance. If you ever feel that the brakes are failing or that the brake calipers have locked up, you have to act fast. The brake caliper may fail due to contaminated brake fluid or when the brake pads have gone too low. Don't wait till your brakes can no longer slow down or stop your vehicle and you're already beating the red light or about to ram into another vehicle.
Checking if the brake caliper has gone bad
Are there cracks or brake fluid leaks on the caliper? Visual inspection will reveal if the caliper needs to be replaced because of cracks. Leaks can usually be traced through streaks or wet spots. The leak may be coming from the caliper piston or one of the brake hoses.
Does the brake caliper still work? You need someone to operate the brakes as you check the caliper more closely. See if the caliper is moving or not. Check if the rotor still turns while someone else applies the brakes.
Is there enough brake fluid getting to the caliper? After locating the air bleed valve at the back of the caliper, connect a small hose to it. The hose's other end must go to a clear jar, which should be filled with clean brake fluid. To keep air from infiltrating the system, make sure that the hose sinks below the brake fluid. The next thing you have to do is open the valve and have someone step on the brakes.
Bubbles in the brake fluid means that there's probably air in the system that needs to be bled out. If there's brake fluid flowing to the jar, then it means that it's getting to the caliper. Otherwise, the caliper has probably gone bad.
Is the brake caliper floating properly? Check if the caliper is moving after applying the brakes. See if it's working well or moving smoothly. If the caliper doesn't budge, you have to figure out whether or not the brake pad is actually trying to move. If it does, then chances are the piston is working well but the caliper isn't floating as it should. In cases like this, the floating pins may need to be lubricated, cleaned, or replaced.
Is the piston at the back of the pad working well? The piston should be applying pressure on the brake pads as you step on the brakes. This makes the caliper float. If there's no attempted movement from the brake pad when the brakes are applied, this indicates a piston problem. The caliper should be replaced if the piston has gone bad.
Another way to check the piston is through a C-clamp placed over the caliper. Compress the caliper piston by tightening the clamp. You'll know that the piston is probably broken if it doesn't even retract or show any resistance. (Note: The same technique may not work on screw-in piston type calipers. Compressing the piston using a C-clamp may result in a damaged piston. In this case, you'll need to use a special tool kit for turning the piston. If this seems stuck, the brake caliper probably needs a replacement.)