Brake Caliper Piston Wont Go Back In – How To Fix the Brakes

If your brake caliper piston won’t go back in, this can cause a lot of trouble since it is one of the braking system’s crucial pieces. The brake system is a necessary feature of every vehicle, and significant issues, such as reduced stopping power and brake pad degradation, might result from a brake caliper piston that won’t retract.

Brake Caliper Piston

In this step-by-step guide, we will show you the signs of a defective brake caliper piston, the reasons for piston failure, and the steps to solve the problem.

How To Fix a Brake Caliper Piston That Won’t Go Back In?

To fix a brake caliper piston that won’t go back in, learn the causes of brake caliper piston failure, gather the necessary tools, use a brake bleeder kit, replace the seal around the piston, clean corrosion from the brake caliper piston, and finally replace the brake caliper piston.

1. Identify the Symptoms of a Bad Brake Caliper Piston

To be able to take the appropriate action to address the issue, you must be able to recognize the signs of a faulty brake piston. Driving with a dragging sensation is the first indication that you could have a damaged brake piston. This happens as a result of the caliper piston not retracting properly, which prevents the brake pads from disengaging from the rotor.

As a result, you can experience a pulling or dragging sensation in your automobile when driving, and the brake pedal might seem spongy or mushy. An unpleasant burning smell is another sign of a damaged brake piston. Due to a blocked caliper piston, the brake pads might create heat and emit a burning odor while they are rubbing against the rotor repeatedly.

After descending a slope or applying heavy braking, you may detect this smell more than usual. If you have a defective brake caliper piston, you can also observe uneven brake pad wear. One side of the brake pad may wear down faster than the other if the caliper piston is not retracting properly, which can result in uneven brake pad wear.

2. Learn the Causes of Brake Caliper Piston Failure

It might be easier to avoid the issue altogether if you are aware of the reasons why brake caliper pistons fail. Knowing these factors can aid in spotting possible problems early on and preventing them from becoming more serious ones. Corrosion ranks among the most frequent reasons why brake caliper pistons fail.

Brake Caliper Piston Failure

The piston of the rear caliper may become caught due to corrosion and be unable to retract properly. It may also result in a burning smell when driving and uneven brake pad wear. A worn-out or broken seal around the piston in the braking caliper is another factor in piston failure. The seal is in charge of preventing dirt, dust, and other debris from getting inside the piston.

If the seal is broken, these particles may do harm to both the piston and the brake system as a whole. Failure of the brake caliper piston can also be brought on by a brake hose that has been damaged or degraded. The piston may not retract properly if the brake line is broken because it might hinder the flow of braking fluid.

Finally, brake caliper piston failure can result from abuse or overheating of the braking system. This can happen if you constantly drive in stop-and-go traffic or up and down steep slopes, which causes the braking system to overheat.

3. Gather the Necessary Tools

You should gather the required tools before attempting to repair a brake caliper piston that won’t retract. The following are the key tools you will require:

  • Jack and Jack Stands: To remove the wheels and reach the brake caliper, you will need to jack up your car.
  • Lug Wrench: To carefully remove the lug nuts holding the wheels in place, you’ll need a lug wrench.
  • Brake Cleaner: The brake caliper must be cleaned using brake cleaner in order to get rid of any dirt or debris that might be the source of the issue.
  • Socket Set and Ratchet: To remove the bolts holding the brake caliper in place, you will need a socket set and ratchet.
  • C-Clamp: The caliper piston must be pushed back into the caliper housing using a C-clamp.
  • Brake Fluid: After bleeding the brake system, you will need to top out the reservoir with brake fluid.
  • Brake Bleeding Kit: After replacing the caliper piston, you’ll need this tool to bleed the braking system.

To prevent delays or extra trips to the shop, it’s important to make sure you have all the required tools before beginning the project. You can precisely estimate the amount of time needed to finish the task by gathering the necessary equipment in advance.

4. Use a Brake Bleeder Kit

It can be required to replace the piston when a brake caliper piston refuses to retract. To make sure that there isn’t any air in the brake lines and that the braking system is working properly in this situation, a brake bleeder kit is essential. Using a brake bleeder kit, you can take the air out of the brake lines and add fresh brake fluid in its place.

Bleeder Kit for Brake

Typically, the brake caliper is where you’ll find the bleeder valve. The braking lines’ air pressure is released through a tiny valve that resembles a nipple. Using the hose provided with the brake bleeder kit, attach the kit to the bleeder valve. To avoid any air getting into the brake lines, make sure the hose is tight. Have someone carefully apply the brakes as you open the bleeder valve.

Any air bubbles in the system will be forced out of the brake lines and into the bleeder kit along with the brake fluid. Check the reservoir’s brake fluid level and top it out if necessary. Make sure that the brake fluid is kept at the proper level. Continue bleeding until there is no longer any air coming from the bleeder kit. Be patient; it can take a few tries to get this right.

5. Replace the Seal Around the Piston

The seal surrounding a brake caliper piston that prevents it from retracting may be worn out or broken. In this instance, changing the seal is required to solve the issue. To reach the piston, you must disassemble the brake assembly and remove the caliper. The caliper should be carefully pulled off once the fasteners holding it to the brake system have been removed.

Replacing the Brake Caliper

Remove the previous piston seal after removing the caliper. To remove the seal, use a screwdriver or a pick tool. Thoroughly clean the piston before replacing the seal. To get rid of any dirt or debris that could be on the piston, use a brake cleaner or a degreaser. Make sure the new seal is properly positioned on the piston when you slide it on. Push the seal into position using a socket or a seal installation tool.

Reattach the caliper to the brake assembly after the new seal has been put in place. Tighten the bolts to the manufacturer’s requirements. A brake caliper piston that won’t retract must first have the seal around it replaced. Leaks and poor braking effectiveness can be brought on by a worn-out or broken seal, which can be risky.

6. Clean Corrosion From the Brake Caliper Piston

The piston may seize due to corrosion, rendering it immobile. To make the piston function again, the corrosion must be removed. To reach the piston, remove the caliper from the brake assembly. The caliper should be carefully pulled off once the fasteners holding it to the brake system have been removed. Take off the brake pads from the caliper.

Cleaning Corrosion From Caliper

By doing this, you will have access to the piston and be able to examine it. Look for any evidence of rust or damage on the piston. It could be necessary to replace the piston if there is any substantial corrosion. You may use a wire brush or sandpaper to clean the piston if the rust isn’t too bad. To eliminate the corrosion from the piston’s surface, move in a circular motion. Take care not to nick or harm the piston.

Thoroughly clean the caliper after cleaning the piston. To get rid of any dirt or debris that could be inside the caliper, use a brake cleaner or a degreaser. Install the brake pads and tighten the bolts to reassemble the caliper once the piston and caliper have been thoroughly cleaned.

7. Replace the Brake Caliper Piston

It could be time to replace the brake caliper piston if none of the above remedies have helped the piston retract. To accomplish this, follow step 6’s instructions to remove the caliper from the brake assembly. To reach the piston, remove the brake pads from the caliper. The old piston should be removed using a piston removal tool.

You can use the tool to assist in forcing the piston out of the caliper bore. When you remove the piston from the caliper, make sure to catch any braking fluid that leaks out. After the old piston has been removed, carefully clean the caliper bore. To clean the bore of any dirt or old brake fluid, use brake cleaner and a wire brush. Put some brake fluid on the new piston before inserting it into the caliper hole.

Push the piston into position using the installation tool. Before pressing it in, make sure the piston is in line with the brake pads. Install the brake pads and tighten the bolts to reassemble the caliper once the new piston has been placed. To ensure that the car brakes are operating properly and to remove any air bubbles, you must bleed the braking system after replacing the piston.

Can a Stuck Brake Caliper Piston Cause the Brake Lights to Stay On?

A stuck brake caliper piston can indeed be one of the brake lights staying on reasons and fixes. When the piston is jammed, the brake pads remain in contact with the rotor, causing excessive friction and generating heat. This heat can trigger the brake light switch, keeping the brake lights illuminated. Resolving the issue involves inspecting and repairing the brake caliper or piston to restore proper brake function and prevent the lights from staying on.


The easy procedures in this article on brake caliper pistons that won’t go back in will help you locate the signs of a damaged brake caliper piston and efficiently repair the issue.

Summing up the key concepts we’ve covered:

  • Brake pad wear that is uneven, difficult braking, and fluid leaks are all signs of a faulty piston.
  • Age, corrosion, and contamination from brake dust or debris are common reasons why brake caliper pistons fail.
  • To fix a jammed caliper piston, you’ll also need a brake bleeder kit, pliers, and brake cleaner, as well as a piston retraction tool.
  • Using a brake bleeder kit, swapping out the piston seal, removing corrosion, and swapping out the piston if required are all ways to remedy a stuck caliper piston.
  • It’s recommended to take your car to a qualified technician if you don’t feel confident doing these duties.

You can maintain your brakes in good condition and have a safer, smoother ride with a little bit of knowledge and effort.

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