Why Doesn’t My Brake Caliper Piston Won’t Go Back In? [Solved]

Owning a vehicle is a beautiful feeling. It’s almost like having a child; a child that needs to be looked after and taken care of just like a human child. It can feel pretty sucky when your precious car starts to show faults, especially with one of its most vital components: braking.

Having fully functional and top-notch condition brakes makes all the difference in the world, and the sudden realization that your brake caliper piston is not retracting can dampen one’s mood.

Irrespective of the time and money you invest in taking care of your car, you are likely to come across several maintenance issues. However, in such a situation, making fast decisions can worsen the problem. 

Instead, you must be patient and calm and determine the root cause of the problems. Once you find the root cause, it will be easy to fix it. One such issue is the inability of the brake caliper piston to retract. 

The brake caliper piston is located within the brake calipers. The calipers play a vital role in pushing the brake pads to the rotors when the operator presses the brake pedal. The calipers usually move back to the original position after the release of the brake pedal. 

However, you may encounter certain situations where the brake caliper piston gets struck. There are several reasons why this occurs.

A few of the main reasons your brake caliper piston won’t go back in are improper wind-back procedure, seized caliper piston, damaged brake hose, or binding type of caliper pins.

How Brake Caliper Pistons Work

How Brake Caliper Pistons Work

Before diving into the working process of the brake caliper piston, it is important to consider the crucial components of the brake. The major components of a brake are:

  • Brake booster –The brake booster allows the operator to apply the vehicle’s brake with minimum effort effectively.
  • Fluid – Fluid refers to the brake fluid. The quality and quantity of the brake fluid are important for the proper functioning of the vehicle.
  • Master cylinder –The master cylinder helps compress the fluid, pushing out the pistons when the foot brake activates them.
  • Brake hoses and lines help carry the pressurized fluids and enable the fluid to reach the brake calipers.
  • ABS pump and modulator apply and release fluid pressure to cause calipers to pulse the vehicle brakes.
  • Rear calipers differ as certain vehicles integrate the caliper and the parking brake. However, it is important to note that the rear calipers demand special attention.
  • Front calipers–Front calipers are available in fixed and floating variants. The main purpose of the calipers is to apply pressure on the brake pad. 
  • Pads –The brake pads are by default held against the rotors. On application of the brakes, the pads get forced against the rotors.
  • Rotors – The discs or rotors remain fixed and keep turning with the wheel. 
  • Shoes –Shoes are no more common in recent times. However, it is good news as replacing the shoes requires effort and demands specific tools.

To understand how the brake caliper pistons work, we need to thoroughly understand how brake pads work and why they are essential.

The brake caliper snugly fits around the rotor, as a clamp would. Within every caliper are two metal plates that have been bonded or assimilated with a certain friction material called brake pads.

The brake pads have been revered as an essential part of the braking mechanism since they are the components that contact and apply pressure and friction to a vehicle’s brake rotors. The friction and pressure applied on the brake rotor are what facilitates the wheel in slowing down and stopping. Once the wheel comes to a halt, the vehicle comes to a halt as well. 

The role of brake pads might sound simple, but their working mechanism is anything but simple!

Brake pads do not stay top-notch forever, and in a brake disc model or system, their shine and ability are diminished by constant contact with the spinning rotor. With constant contact, the brake pads begin thinning down. To compensate for this tear, the piston emerges from its cylinder.

Reasons Your Brake Caliper Piston Might Not Retract

Essentially, the role of a brake caliper piston is to squeeze a brake pad against the surface of the rotor to slow down the vehicle.

So, you can now imagine how the malfunction of the brake caliper piston affects our brake pads, which subsequently affects the car’s ability to brake or stop altogether.

Having a faulty or worn-out brake caliper piston ruins your vehicle’s smooth running and braking and would cost you hundreds of dollars to install new components or fix the issue later on when it’s much worse. By following this guide, you can avoid burning a hole in your pocket and keeping your precious car in perfect condition!

Top 4 Reasons for Your Brake Caliper Piston Won’t Go Back In

#1 Binding Brake Caliper

Binding Brake Caliper

A binding brake caliper applies to the floating type of calipers that are installed in most cars these days. Usually, expensive and classic or limited edition cars have fixed calipers installed in them. The simple distinction between these two is quite crucial and straightforward, one is immobile and the other can freely move.

For the smooth movement of floating or sliding, bushings and pins are used within the caliper.

Issues occur when the caliper pins rust or if the bushing breaks down, causing the caliper to bind rather than float.

To determine if you are facing this issue, you need to open and check the fluid reservoir and with the help of a screwdriver, proceed to push the brake piston downwards.

Move the caliper and nudge it back & fro; if you feel there is a restriction of movement, you have a problem.

Solution: You can try to remove and take apart the pins from within the brake carrier. Usually, in certain instances, the pins might be bolts and upon seizing within the carrier, they become tough to remove without the help of cutting tools. Either way, you would need to replace the bolts.

You should acquire the assistance of your local mechanic while replacing the bolts.

#2 Seized Caliper Piston

Seized Caliper Piston

If your brake caliper piston does not compress, a corroded or seized caliper piston might be the reason. Several reasons can cause seizing of the brake caliper pistons. One of the most common reasons is inactivity. 

The brake caliper pistons can get seized when you leave your vehicle unused for several months. Moreover, the inactivity of the vehicle may also result in corrosion. Rust or corrosion often limits the brake calipers from operating correctly. 

Any amount of rusting of the piston boot will affect the ability of the caliper piston to move back. When you use your car regularly, the chances of rusting are quite less. However, inactivity or driving it on rainy days can lead to corrosion, resulting in caliper pistons seizing. 

Worn-out boots or seals are yet another reason for seizing the caliper piston. After certain years, the piston seals usually get worn out. With time, the piston seals completely fail. 

Therefore, the piston gets seized. However, the rubber boot can also be the reason for seizing the caliper pistons. The rubber boot on the piston helps keep it lubricated and protects it. But in case of damage to the rubber, water gets into the piston and seizes. 

Some of the signs that indicate potential seizing of caliper pistons are: 

  • Smoke coming out from the wheel
  • Slowing down of the car than normal
  • Pulling of the car towards one side
  • Covering of a single wheel over brake dust
  • Car hard on the gas. 

Solution: You will have to open the fluid reservoir using a screwdriver to diagnose the problem. Try pushing back the piston. You can expect a frozen caliper if you see the piston won’t retract.

However, a collapsed brake hose can also be a potential reason. Take the help of a professional mechanic to identify the exact problem. In case you find out that your caliper piston has seized, a simple solution to the problem is to replace it.

However, in addition to it, you can also consider changing the brake fluids and using new pads for better functioning.

#3 Incorrect Wind Back Procedure

Incorrect Wind Back Procedure

In case you are working on a rear caliper that just will not retract, ensure that you are following the right service procedure. Rear calipers are not like front calipers and require different methods.

Rear calipers do not easily get pushed inside, the piston has to be turned and pushed in. A simple wind-back tool is used to turn and simultaneously push the rear caliper pistons inwards.

Parking brakes come in two versions:

EPB – electronic push button parking brake

How to retract a rear caliper with Manual Parking Brake:
The rear calipers incorporate the parking brake by fitting in a brake lever and cable to it. The manual brake needs to be released before following the removal method.

To retract the rear caliper you need to use the wind-back tool to turn and push the piston. Do keep in mind that some calipers turn clockwise and some might turn anti-clockwise so do not forcefully push them in the wrong direction.

Keep turning and pushing till the piston fully retracts.

Now when it comes to retracting the piston in EFB versions, you would need to acquire the assistance of your local mechanic as the components are trickier to take apart and handle than the manual parking brakes.

Another point we should address is the causes of frozen calipers!

#4 Brake Dust

One of the prominent reasons why your brake caliper piston does not go back is the presence of dust. The brake pads do release a lot of soot and dust on being rubbed against the surface of rotors. 

With time, the piston starts getting covered with dust and soot. Therefore, the piston gets stuck and is unable to move in.

Brake Dust

However, the good news is that the solution to this issue is quite simple and easy. All you need to do is take a clean cloth or a soft brush and clean off the dust. This can increase the chances of the piston going back in.

But you may have to apply a little pressure with the use of an appropriate clamp. It is essential because the brake caliper piston may not move back in due to insufficient pressure.

However, you need to keep in mind that the mechanism of the rear brake caliper pistons is different from the front ones. The rear pistons require turning and pushing in simultaneously with the application of the wind-back tool.

#5 Collapsed Brake Hose

A collapsed brake hose is another reason that makes it difficult for the brake caliper piston to move back in. The main functionality of the brake hose is to enable the effective flow of the brake fluid to the braking system and then back to the master cylinder. 

Brake Hose

However, the breakage or collapse of the brake hose limits the brake fluid from flowing back to the master cylinder. It makes the caliper get stuck. However, there are several cases in which the caliper doesn’t get stuck. 

The broken hose makes your brake feel like the calipers are stuck in certain cases. Therefore, it is important to make a thorough inspection to identify where exactly the problem is. 

To diagnose this issue, you will require opening the bleed nipple of the brake caliper. While opening the nipple, try pushing on the piston using a screwdriver.
If fluid comes out from the bleed nipple and the piston can retract, the brake hose is at fault. 

Resolving this issue is very simple. All you need to do is replace the brake hoses. Ensure to replace all the hoses as there is a high chance that the other hoses are internally breaking down.

Another point we should address is the causes of frozen calipers!

Common causes your caliper might be frozen

Bad or contaminated brake solution is one of the main causes leading to the failure of the caliper to function optimally. Brake fluid is what attracts and traps moisture but the same moisture trapped within the brake system begins to rust and decay all the vital mechanical components, which gradually causes the pistons to seize within the cylinder.

You need to make sure that your brake fluid is changed every three to four years or so for a smooth-running hydraulic system. If you do not invest time and effort into taking care of your brake fluid and other nitty-gritty things, you might have to spend hundreds of dollars later in life!

Other Reasons Why The Brake Caliper Piston Doesn’t Go Back In

In addition to the above reasons, other causes can limit the caliper piston from moving back. Here are some of the potential other reasons. 

Brake Caliper Piston
  • The piston might be hitting a hard spot. To resolve this issue, you can try clamping the piston to apply pressure for some time. Then try running the piston in and out several times to see whether the situation gets better or not.
  • Lack of even pressure can also be a potential cause. When you compress the caliper piston, apply even pressure on the complete area. If the pressure is not applied on the full area or is off-balance, the piston is not likely to move back in.
  • Deformation of the caliper piston is also why your brake caliper piston does not go back in. Even if the piston is slightly bent, it can affect its compression. Therefore, fixing this problem will ensure that your brake caliper piston easily moves back in.

Best Ways to Resolve the Brake Caliper Piston Problems

When you find that your brake caliper piston cannot move back in, it is important to fix the problem immediately. If the brake caliper pistons do not work properly, it can eventually result in brake failure. 

This, in turn, can make you land in a very dangerous position. Therefore, resolving the issue at the earliest time possible is crucial.

To fix the brake caliper piston issue, some of the best ways are:

Clean the Brake Caliper Pistons

One of the simplest solutions is to clean the brake caliper pistons of your car thoroughly. This will help effectively remove the corrosion and dust buildup on the piston. Moreover, it can serve as a simple fix to solve the compression issue before costly fixes.

Clean Brake Caliper Pistons

Ensure Timely Maintenance

Owning a car is not just enough. However, regular maintenance is highly important to ensure that all the parts of the care are in good working condition. The brake caliper piston often arises due to a lack of filling the brake fluid. 

Not replacing the brake pads on time can also be a potential cause. Therefore, taking good care of the brakes can help prevent caliper piston problems. 

Use the Piston Compression Tool

You will have to use the piston compression tool to solve the problem. Having the special compression tool can make your task a lot easier. Make sure that the compressor is accurately adjusted to get the job done in the right way. 

Place the caliper compression in line with the caliper present in front of the pad. Then try pumping the compression tool downwards while the push bar puts pressure on the brake pad. It will help in enabling the brake caliper piston to retract easily. 

Make Use of a Screwdriver

You can always use the special piston compression tool for the best outcomes. However, all you need is a simple tool such as the screwdriver at times. Instead of any fancy tools, a standard screwdriver can get your task done in the best way. 

Place the screwdriver in the caliper window. Make sure to hold it tightly while fitting it in the opening. The pulling motion must result in the pulling back of the caliper piston. 

Once the screwdriver is in the proper place, try slightly pulling back. 

Ensure that the pressure you apply is against the pad and in an outward direction. Now, you can put the screwdriver between the brake pad and piston. This will help in gently pushing back the brake caliper piston. 

Essential Precautions

When working with the car brakes, there are several precautions that you need to keep in mind. One of the important precautions is tothat make sure not to leave the caliper hanging. It is important as it puts strain on the brake lines. 

Moreover, ensure that the brake fluid doesn’t come in contact with your car’s paint. If it happens, it can cause significant damage to your care paint. Also, make sure not to leave the brake fluid reservoir open for long. 

This can result in the absorption of moisture. In the case of installation of new brake pads, loosen the bleeder valve. This will help in releasing the excess fluid from the system. Moreover, make sure to use an appropriate clamp to push back the caliper piston. It will prevent any damage to the piston. 

Cost of Fixing the Brake Caliper Pistons

If you can fix the problem with the tips given in the article, you will not have to spend anything. However, if these tips do not solve your problem, you may require replacing the caliper pistons. 

When it is about replacing the pistons, you will incur some costs. But the cost to fix the caliper piston issue will differ. It will depend on several factors, such as the type of vehicle, the model of your car, and local labor charges.

You can opt to restore your brake caliper using new seals and a piston. However, it is always a better option to get a new caliper. This can help you lower your overall costs.


Is it Possible for a Struck Caliper to Fix itself?

A seized or stuck caliper will in no way get repaired itself. You will have to replace it on an immediate basis. A frozen caliper can result in brake imbalance, leading to safety hazards. Therefore, it is important to replace the brake caliper at the earliest time possible.

Can you put back the Rear Piston in a Caliper?

Yes, you can put back the rear piston in a caliper. To do so, you will require simple tools such as screwdrivers or pliers. Try twisting the piston in a clockwise direction with a screwdriver or plier. This will help in spinning the piston inwards into the caliper. After doing this, you can easily change your car’s brake pads.

What causes the Sticking of Brake Calipers?

There are a variety of causes of sticking brake calipers. The main causes include rusty pistons, rusty brake pads, dirty caliper pins, and broken brake hoses. However, old or dirty brake fluid is another significant cause. 

How can you Avoid the Sticking of the Brake Calipers?

Sticking the brake calipers is a common problem for car owners. It mainly occurs due to the brakes’ lack of proper and regular care. However, the good news is that there are several ways to avoid the sticking of the calipers. Here are some of the best ways to avoid the problem.
– Change your brake fluid once every one to three years
– Clean the guide pins, brake pads, and brake pistons once every two to three years.
– Break hard at times when your car is in high speed
– Make use of the parking brake.

Is it Essential to Grease the Caliper Pistons?

No, you do not have to grease the caliper pistons often. However, if you are opting for replacing your car’s brake pads, you can clean and lubricate the piston at that time. Grease is usually added to the piston in between the installation process of the brake pads.

What are the symptoms of low refrigerant?

Low refrigerant symptoms include weak or no cool air from AC vents, longer cooling times, frost on the AC evaporator, and hissing noise from the AC system when the engine is off.

How do you know if your AC just needs Freon?

You will know if your AC needs Freon when it is blowing warm air, taking a long time to cool, or making unusual noises.

How often does Freon need to be replaced in the car?

Under ideal conditions, Freon should last about 3-4 years in a car. However, factors like leaks, extreme weather, and frequent AC use may require more regular checks. With proper care and maintenance, the lifespan of Freon gas can extend up to five years.


We know that all the technical terms might make you feel a bit overwhelmed, but don’t worry! It is pretty simple and easy once you start the procedure and follow our steps.

A brake caliper piston might not retract due to a variety of reasons from improper wind-back procedure, seized caliper piston to loose or stiff binding within the caliper.

Bad or contaminated brake fluid is also a major cause and should not be overlooked or left pending for too long.

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