Your brakes are the most important safety equipment in your car. If they fail, then it is more than likely to cause a serious accident.
For this reason, any problems associated with the pedal sinking or not returning need to be dealt with quickly to avoid causing an accident.
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Why Doesn’t My Brake Pedal Return After I Press It?
If the brake pedal doesn’t return after it’s pressed, the problem is due to air in your brake lines. Either your brake master cylinder or the brake booster is faulty or air has entered from the pistons at the brake caliper. The lack of hydraulic pressure is the reason the pedal doesn’t return.
Internal or External Leaks
There are two main reasons why pedals sink to the floor and then don’t return to their original position.
The brake system loses pressure from either an internal or an external leak. To start the search, you need to get underneath your vehicle and check the brake calipers and the brake drums (if you have them on the rear wheels).
Looks for Pools of Brake Fluid
You’re looking for signs of brake fluid leaking or dripping from any part of the brake assembly.
Tell-tale signs will be a dark fluid mark on the interior of your rims and tires, or a pool of brake fluid on the floor under the car.
Check your Brake Fluid Reservoir
You can also check your brake fluid filler cap on top of the master assembly to see if the fluid level is below the minimum mark.
When your pedal sinks to the floor very easily with minimal pressure and doesn’t come back up again or returns very slowly, then you can be sure that the level of fluid in the master cylinder reservoir is very low.
You may very well find that the reservoir is empty.
Check the Brake Lines
If you fail to see any signs of leakage around the wheels, calipers, or rubber hoses, then check the steel brake lines that run underneath the car, as well as the lines running from the master cylinder to the brake calipers.
It is unlikely that the brake lines will leak unless they are rusted. Rusted brake lines are only a problem on very old cars or in regions where salt is used regularly on the road to disperse ice.
This leaves the brake master cylinder or the booster as the possible culprits. In the absence of brake warning lights, the master cylinder is the most likely cause.
Check the Brake Master Cylinder
If air gets into the brake master cylinder then it is likely to ruin the seals. Look for damage to your reservoir cap or signs that there are leaks or rust around the master cylinder.
You can buy rebuild kits for the master cylinder or you can purchase rebuilt master cylinders.
I’d advise against this, as purchasing good quality, replacement master cylinder is easier and less likely to give you problems later.
Many rebuilds have quality issues and unless you know what you are doing, fitting parts from a rebuild kit may not fix the problem.
Before buying a new master cylinder, it’s worth trying to bleed the air out of your brake system to see if you can return the brake pedal to its original position.
It’s worth filling the brake fluid reservoir and getting the air out to see if that solves the problem before going to the expense of purchasing a new master cylinder.
Jump to the section on bleeding the air out of your brake system to see how it is done.
How to Replace the Brake Master Cylinder
Replacing the master cylinder is straightforward. You can get it done with minimal tools and an hour or two of your time.
After buying a good quality master cylinder, loosen the brake lines attached to the cylinder. Use a flare wrench to avoid damaging the connection.
After removing the front and back lines, place a rag under each open line to catch any brake fluid drips.
You want to avoid getting brake fluid on your paintwork as it is extremely corrosive and will burn through the gel coat in a heartbeat.
Next, you must unscrew the two bolts that hold the master cylinder to the firewall.
Once the bolts are loose, you can lift the master cylinder clear of the vehicle. Wrap a cloth or rag around it to prevent any brake fluid from dripping onto the paintwork.
You can now replace the master cylinder with the new one and bolt it in place. Screw the front and back brake lines in finger-tight.
7 Steps How to Bleed the Air Out of Your Brake System
1. Fill the Brake Fluid Reservoir
Open the filler cap and pour in as much fluid as you need to get it up to the MAX line. Replace the cap.
Then make sure that the brake line connections are loose so that the air can bleed out when you step on the brake pedal.
2. Step on the Brake Pedal
Have someone push the brake pedal to the floor and hold it there. Whatever they do, they must not let the pedal go until you tell them to.
If you are on your own, you could use a long screwdriver or piece of wood to wedge between the seat and the pedal after you push the pedal down. Slide the seat forward to apply pressure.
Pushing the pedal down will expel the air from the brake lines. That’s why you want the connections only finger-tight and then backed off a turn or two.
3. Tighten the Brake Line Connections
With the pedal pushed to the floor, tighten the brake line connections on the master cylinder.
Once they are tight, no air will be able to suck back in as you release the brake pedal.
4. Release the Brake Pedal
After releasing the pedal, push it back down again and wedge the screwdriver in place to prevent it from coming up again.
Now use a wrench to loosen the brake line connections a couple of turns.
You may notice a few bubbles coming out around the threads together with some brake fluid.
5. Tighten the Brake Line Connections
After a little while, the air will bleed out of the lines and the bubbles will stop. Then tighten the connections again and release the pedal after they are secured.
6. Repeat the Procedure
Follow this procedure a few times until there is no more air coming out and the pedal feels hard when you push down on it.
7. Check the Brake Fluid Level – Important!
Take note of the brake fluid level in the brake fluid reservoir after each bleed. If the level drops, top up the reservoir.
You don’t want the level to drop below the MAX line as you may inadvertently pull air back into the master cylinder again.
If this happens, you’ll have to start the whole process over again from scratch.
If the brakes are still spongy and not rock hard after bleeding the air out of the master cylinder, you may have to bleed the air out of each of the brake lines leading to the wheels.
How to Bleed Your Brakes at the Brake Calliper
The simplest method is to locate the bleed screw on each caliper.
Starting at the wheel furthest from the master cylinder, work your way round to the brake caliper closest to the master cylinder.
Loosen the Brake Fluid Filler Cap
Loosen the brake fluid filler cap to stop a vacuum from forming inside the reservoir when bleeding the brakes.
You will most probably need to remove the wheel to reach the bleed screw unless you have a hoist.
Locate the Brake Calliper Bleed Screw
Place a wrench over the bleed screw (remove the rubber cap protecting it first) and have someone depress the pedal.
Follow the earlier process with a screwdriver or piece of wood if you are alone.
Depress the Brake Pedal and Open the Bleed Screw
With the pedal depressed, unscrew the bleed screw a half or three-quarter turn, and watch carefully for any bubbles that may appear.
There will be a lot of brake fluid flowing out, so you might want to attach a piece of tubing so that the fluid runs down into a bottle.
If you fill the bottle with brake fluid first, with the other end of the tubing under the surface, you’ll prevent any air from getting sucked back into the system if the brake pedal is released before the bleed screw is tightened.
Tighten the Bleeds Screw and Release the Brake Pedal
Release the pedal and push it down again, holding it in place and releasing the bleed screw.
Repeat the process a few times until you only get clear fluid and no air bubbles coming out. Move around all four wheels until you have bled each line going to the master cylinder.
Once you are finished bleeding the brake lines, the brake pedal should be rock hard and return to its original position after applying brakes.
Frequently Asked Questions on Why a Brake Pedal Doesn’t Return After it’s Pressed
How do you know if you have air in your brake lines?
The clearest indication that you have air in your brake lines is a spongy brake pedal or a brake pedal that falls away under your foot when you apply the brakes.
What are the symptoms of a faulty brake booster?
Your brake booster may be faulty if your stopping distances increase and you have to press harder on the brake pedal than normal. You may also see the ABS or brake warning lights illuminate on your dashboard.
Can a master cylinder fail without leaking?
Your master cylinder can fail without leaking. If the seals inside the cylinder on the piston fail, brake fluid can escape around the edges of the piston, causing it to stop working.
Conclusion About Why Doesn’t My Brake Pedal Return After I Press it
While a brake pedal that doesn’t return properly is a major safety concern, fixing the problem is well within the average DIY mechanic’s ability to fix.