Every car owner/driver should know how to bleed brakes. Even if you won’t do it yourself at the very least you should know what it is, why it’s important, and the procedure for doing it.
Why do I say that?
For starters, it is one of those repair jobs that must be done periodically throughout the lifespan of a vehicle. Secondly, it ensures that the car’s brakes work efficiently without fail. That makes it one of the most essential repair jobs as far as vehicle safety is concerned.
- 1 What Exactly Is Brake Bleeding?
- 2 When Should You Bleed Your Brakes?
- 3 How Often Should You Bleed Your Brakes?
- 4 What Happens If You Don’t Bleed Your Brakes?
- 5 What Tools Do You Need to Bleed Brakes?
- 6 How To Bleed Brakes: What Are The Available Methods?
- 7 How Can You Prepare Your Vehicle For Brake Bleeding?
- 8 How to Bleed Brakes by Yourself (How to Bleed Brakes with One Person)
- 9 How to Bleed Brakes with 2 People (Pump and Hold Method)
- 10 How to Bleed Brakes with ABS
- 11 Do I Need To Bleed All 4 Brake Lines?
- 12 Is It Better to Bleed Brakes with Car On Or Off?
- 13 Do You Need to Bleed Brakes After Replacing Pads?
- 14 My Brakes Won’t Bleed, What Could Be The Problem?
- 15 What Does It Cost to Bleed Brakes?
What Exactly Is Brake Bleeding?
By definition, bleeding brakes refers to the process of removing air from the brake line. It’s not uncommon for tiny amounts of air to find their way in there.
Over time, that amount increases. While every air bubble is a cause for concern, you will know that it has reached an extremely worrying level when you get a spongy feeling every time you step on the brake pedal.
That spongy feel is brought about by the fact that air is compressible (contrary to brake fluid). And if a large amount of it gets trapped in the brake line, your car may experience a complete braking failure. That right there is the reason why you should know how to bleed brakes.
When Should You Bleed Your Brakes?
The simple answer is that you should bleed your brakes whenever you see signs of inefficiency. There are several key indicators to look out for. As I’ve already mentioned, the first is a feeling of sponginess or squishiness whenever you hit the brake pedal.
Besides that, check the level of fluid in the master cylinder. If you find that it is low chances are the brake line has a leak. The entire braking system should be closed, and therefore if fluid escapes it means that there’s an opening somewhere.
The opening will not only leak out brake fluid but it will also allow air into the braking system. If the car pulls to one side when braking you could also be dealing with a leaky brake line or brake pad. In both cases, your priority should be fixing the leak and then bleeding brakes.
For ABS brakes, the ABS warning light may come on to indicate a problem with the braking system. There are many triggers for the light, and one of them is a leaky brake line. In that case, follow the same drill – fix the leak and then bleed the brakes.
How Often Should You Bleed Your Brakes?
Regardless of the above signs, most brakes generally require bleeding after two or three years. Most brake fluids fall in the Glycol family of organic compounds. As such they naturally absorb moisture.
In just one year your vehicle can have up to 2% water content in its brake fluid. That can rise to well over 3% in under 2 years. In some cases, especially when the brake fluid is too old, water can account for 13% or more.
Alongside sponginess, a high amount of water leads to corrosion and may result in absolute brake failure. If you know how to bleed brakes you can avoid all that simply by removing the air yourself.
Otherwise, you may have to pay a pretty penny to get it done at the shop. Either way, 3 years should not pass without your brakes being bled.
What Happens If You Don’t Bleed Your Brakes?
Failure to bleed brakes means that your brake fluid will have moisture. That may have so many undesirable effects. Primarily, the boiling point of the fluid will reduce significantly.
If the brake fluid had a boiling point of say 400 degrees when new, it may reduce to 250 degrees or less after saturation. That usually leads to something known as “brake fade”.
Brake fade is basically a situation where the brake fluid easily hits its boiling point. Consequently, it produces steam which lingers in the braking system (brake line, calipers etc.). The grand effect of that is a fading brake pedal.
No matter how hard you hit the brakes the car will still have a long stopping distance. In other words, you won’t be able to do an emergency stop. You may also have a hard time braking smoothly in stop-and-go traffic.
In some cases, the car may fail to stop completely until the fluid cools down again. That’s how some life-threatening accidents happen.
The other effect of saturated brake fluid is that your car’s brake pads will wear out prematurely. What happens is that the water molecules in the brake fluid will turn into steam when the brake fluid heats up.
Steam expands more than water, and it, therefore, applies more pressure to the brake pads. Meaning your brakes may be engaged (slightly) even when you are not stepping on the brake pedal. In other words, you may end up driving with the brakes engaged and you won’t even know it.
Finally, moisture is the primary culprit in corrosion. So it’s not just your brake pads that will wear out faster, other metallic components of the braking system will too.
What Tools Do You Need to Bleed Brakes?
There are certain tools that you should have when attempting to bleed brakes. The exact set of tools depends on the bleeding method you choose. That said, here is a list that covers ALL the tools required for ALL types of brake bleeding:
1. Can of brake fluid: You will need at least one of those if you are only going to bleed lines. Otherwise, if you want to do a full replacement at least 3 cans should do.
2. Turkey Baster: You may need it to clear the master cylinder of old brake fluid and accumulated debris.
3. Wrenches: Drum brakes require an 8mm wrench while disc brakes require a 10mm wrench. Double check to ensure that that’s the case.
4. Brake cleaner: One can get the job done.
5. 4 jack stands or one car lift: Either of those should help lift your car off the ground.
6. Disposable plastic bottle.
7. Clear plastic tubing: You should be able to see fluid flowing in the tube.
8. Depending on the bleeding method, you will also need one of the following:
- A helper (assistant) for the two-person method.
- A pressure pump (required in the one person method).
- A vacuum pump (required in the one person method).
- One-way bleeder screws for the one person method.
It’s important to have all your tools ready way before starting the bleeding process. I won’t lie to you, the job can be a bit tiring. The last thing you want is having to walk long distances in search of a tool.
How To Bleed Brakes: What Are The Available Methods?
There are five different methods of bleeding brakes. I’ll cover them in details later on in this post. In the meantime here’s a brief description of each:
1. Pressure pumping
This method involves attaching a pressure pump to the fluid’s master cylinder. By doing so, the whole braking system is pressurized. Proceed to open the bleeder valves one by one until the fluid is free of air.
Pressure pumping is very effective at flushing dirty fluid from the braking system. However, some cars usually require a special adapter for sealing the master cylinder. That amounts to an extra expense on your part.
2. Vacuum pumping
Attach your vacuum pump to the bleeder valve and then open the valve. Use the pump to extract fluid until it is free of air/moisture bubbles.
Although it’s the easiest type of brake bleeding, vacuum pumping is the least effective. More often than not you will be advised to use it alongside another bleeding method.
3. Gravity bleeding
With the master cylinder full, loosen the wheel calipers and attach a clear tubing to the bleeder valve. That will route the brake fluid from the wheel (and into a bottle). Let the fluid run until it’s clear and free of all bubbles.
Do the same for all the remaining wheels. Although this method is arguably the slowest, it is the most harmless to your vehicle. I will discuss it some later on in this post, so read on and learn how to bleed brakes using gravity bleeding.
4. Pump and hold
Here, press the brake pedal while opening one bleed screw at a time. Doing that allows trapped air to escape. The tricky part is that the bleed screw should be closed before the brake pedal is released. That is what makes it a two-person job – one person to press the pedal and the other to open and close bleed screws.
In case you don’t have an assistant you can consider using a one-way valve that only allows air out and not in.
5. Reverse bleeding
This method involves injecting fluid through the bleeder valve. By forcing fluid through the valve, it pushes air, forces it to travel in the fluid, into the master cylinder and eventually to escape outside.
Some professional mechanics advocate for this method because it is impressively effective. However, it requires that you flush the whole system prior to bleeding. Plus the bleed screw must be unplugged.
How Can You Prepare Your Vehicle For Brake Bleeding?
Above are the methods of how to bleed brakes. Conveniently, regardless of the one you choose, you will use the same basic tools. So start by having all these tools well organized at your workstation at least one day prior.
Also, you could apply penetrating oil to bleeder valves a day before. That will make them fairly loose and easy to open. Keep in mind that they are hollow valves. Applying too much pressure can easily damage them. Don’t tap them with a wrench either.
When the bleeding day comes to start by lifting the vehicle with your 4 jack stands or the car lift. Remove all the wheels and then place a hard piece of material (like wood) under the brake pedal to prevent it from falling to the floor as you work.
Make sure that the fluid reservoir is fully filled before you start. Also, keep refiling it all through the bleeding process. Remember to close the reservoir every time you’re done refilling it.
When connecting your plastic tubing to the disposable bottle, ensure that the tubing is long enough. You don’t want it to detach from the valve when you’re in the middle of bleeding.
Be sure to have a sufficient amount of new fluid in the bottle at all times. Generally, the tubing should be fully immersed in the fluid so that it doesn’t suck air back into the brake system.
Finally, keep some old rags with you through the entire process. Brake fluid is very strong and will ruin your car’s paint job upon contact. It would be a long stretch (and probably unrealistic) to say that the fluid shouldn’t spill on the car. So, to prevent damage, use the rags to clean it off immediately.
How to Bleed Brakes by Yourself (How to Bleed Brakes with One Person)
You can use any one of the 5 methods to bleed brakes by yourself. However, the pump and hold method requires that you have a one-way valve if you are going to do it alone. Otherwise, all the other 4 methods are a one-person job.
Out of all of them, pressure pumping and vacuum pumping are arguably the easiest. Gravity bleeding, on its part, is very harmless. Most professionals recommend it for DIYers. In this section I’m going to give the procedures for those three methods then, later on, I’ll cover how to bleed brakes with two people using the pump and hold method.
1. How to Bleed Brakes with a Pressure Pump
This method requires new brake fluid, wrenches, about 10 inches of clear rubber tubing, jack, jack stand, wheel wrench, cleaning rags, turkey baster or vacuum pump and a pressure bleeder kit.
Step 1: Clean the area around the master cylinder. You don’t want dirt and debris all over the place because they can contaminate the reservoir.
Step 2: Check the reservoir cap for the recommended brake fluid. If it’s not indicated there check your vehicle’s owner’s manual. Make sure you have at least 0.5L more than the capacity of the reservoir.
Step 3: Using the turkey baster or vacuum pump, remove the old brake fluid from the reservoir. You might not be able to remove all of it, but make sure you take out as much as possible.
Step 4: Take the pressure bleeder’s cap and use it to close the opening of the master cylinder. These kits come with generic caps, so pretty much every one of them will fit. Make sure its tight enough not to allow air into the system.
Step 5: Connect the feeder line. A feeder line has two ends. One of them has a valve and a quick release. That one goes to the cap on the reservoir. The opposite end attaches to the pressure bleeder.
Step 6: Check for leaks in the feeder line. You can do this by turning the valve off and then pumping the system to 15psi. Monitor the gauge to see if there’s a drop in pressure. If the pressure does drop it means that there’s a leak; either where the feeder line connects to the pressure bleeder or the valve. Check the connections to ensure they are tight enough to prevent leaks.
Step 7: Release the pressure, disconnect the feeder line from the pressure bleeder and then fill the pressure bleeder’s tank. Make sure there’s enough brake fluid in the tank so that it doesn’t run empty and suck in air.
Step 8: Reconnect the feeder line with the pressure bleeder. If you had removed its valve from the cap (on the reservoir) reconnect it as well. Ensure that both ends fit tightly.
Step 9: Pump the pressure bleeder to about 15psi. The value is not set in stone; in fact, it varies from one car to another. Check the owner’s manual to see whether there’s a recommended pressure value. If not, go with 15psi. By all means, try not to exceed 20psi. When the pressure is too much it may damage seals within the braking system.
Step 10: Did you remember to jack the car off the ground at the start of the process? If not this would be the second best time to do that. In case you only have one jack you can lift one wheel at a time.
Step 11: Start with the farthest wheel from the master cylinder. That should be the rear wheel on the passenger side. This is the case in almost all vehicles, although there are some exceptions. Again, you can find directions in the owner’s manual.
Step 12: Locate the bleeder screw. It’s usually covered with a plastic cap. Open the cap and the clean the bleeder thoroughly to remove any dirt and debris. Connect your clear plastic tubing and direct it (the tubing) to a clear water bottle.
Step 13: Loosen the bleeder. Doing that will allow the old brake fluid to flow out through the tubing and into the water bottle. Meanwhile, the pressure pump will feed the line with the new brake fluid. Since it is pressurized, the pump won’t allow air into the system.
Step 14: Observe the fluid flowing through the rubber tubing. Wait until the old fluid is completely out before tightening the bleeder. You will know that it’s all drained out when the new fluid starts flowing in the tubing.
Side Note: usually, the farthest wheel will drain the most fluid because it has the longest line. Your water bottle should be at least 1L in capacity. Also, during the process fluid may come into contact with the car’s paint. Use clean rags to clean it off immediately so that it doesn’t damage the paint job.
Step 15: Once all the old fluid is out tightened the bleeder, reattach the wheel and then move to the next wheel. That should be the second farthest from the master cylinder; i.e. the rear wheel on the driver’s side.
Step 16: To bleed the second wheel repeat steps 12 all through 14. The only notable difference is that you will collect lesser old fluid as you move closer to the master cylinder.
Step 17: Proceed to the third wheel; the front passenger wheel. Repeat steps 12 to 14.
Step 18: Work the final wheel. Again, simply repeat steps 12, 13 and 14 to drain all the old fluid.
Side Note: during the process, you may notice the psi reading dropping slightly. If you had it at 15 it may drop by 1 or 2 points, more so when you are working on the farthest wheel. That shouldn’t be a cause for worry. But if it drops significantly, says by 5 points then there could be a leak in the braking system.
Step 19: Remove the pressure bleeder. It’s best to disconnect the cap from the reservoir first. Doing that will ensure that you close the reservoir as fast as possible. You don’t want to leave it open for too long because brake fluid absorbs air and moisture.
Step 20: Just to be sure, get in the car and check the pedal feel. Do that when the engine is running. The pedal should neither feel spongy nor squishy. It should be firm.
2. How to Bleed Brakes with a Vacuum Pump
Here you will need the same tools that are needed for pressure pumping. The only difference is that while in pressure pumping we used a pressure bleeder, this method employs a vacuum pump.
So, instead of buying a pressure bleeding kit you will have to buy a vacuum pump. The benefit of that is that the vacuum pump can come in handy when you need to diagnose other systems, like thermal control vacuum switches, EGR system, positive crankcase ventilation (PCV) system etc.
Step 1: Clean the area around the master cylinder. That should prevent dirt and debris from entering the braking system and contaminating it.
Step 2: Using a turkey baster or vacuum pump, remove as much brake fluid as possible from the reservoir. Add the new fluid up to the point marked MAX.
Step 3: Without tightening it, put the cap back on the reservoir. Make sure it’s slightly loose so that a vacuum doesn’t form.
Step 4: Prepare your pump by putting about 1.5 inches of tubing between the lid of the reservoir jar and the pump. Next, attach a 3.5-inch hose to the bottom of the cap.
Step 5: On the other reservoir jar, affix 12 inches of tubing. The end of this latter tubing is where the universal adapter goes. This adapter fits on virtually all bleeder valves snuggly. In all these connections, make sure that they are tightly fit.
Step 6: In case you hadn’t jacked up your car now would be the appropriate time to do that. Remove the wheels to get easy access to bleeder screws. You can remove all the wheels before starting the bleeding process or remove one wheel at a time as you bleed its brakes.
Step 7: Start with the farthest wheel (rear passenger wheel). Clean its bleeder screw thoroughly and then place your wrench in position (on the bleeder). Don’t open it yet.
Step 8: Connect the adapter alongside the vacuum kit assembly on the bleeder screw. Now, loosen it slightly. If it’s too tight feel free to apply some pressure, but don’t force it because it may get damaged.
Step 9: Without starting the car’s engine, pump the brake pedal 10 to 15 times. Use the normal foot pressure. This should remove any residual vacuum from the brake booster.
Step 10: Add some more fluid to the reservoir to bring the level back to the MAX point. Without tightening it, place the cap back on the reservoir.
Step 11: Now squeeze the pump handle 10 to 15 times. Open the bleeder screw some more (to about 0.5 inches) to let the old brake fluid flow into the blender jar.
Step 12: Keep pumping until the old fluid is all in the jar. You will know that when you see new fluid starting to flow into the jar. Once that is achieved tighten the bleeder screw and then move to the next wheel.
Step 13: Repeat steps 7 through 12 for the rear driver, front passenger, and front drive wheels. Each time make sure you have topped off the reservoir so that it doesn’t run empty.
Step 14: After bleeding all the four lines, start the car’s engine and press the brake pedal to check whether it still feels spongy. It shouldn’t. If it does then that means either there’s a leak or there was a problem with the bleeding. You will have to start the process all over again.
3. How to Gravity Bleed Brakes
For this procedure, you will need at least one liter of new brake fluid, a hammer, masking tape, empty bottle for holding used fluid, 3/16 plastic tubing (at least 5 feet), jack stands and a pair of vise grips.
Step 1: Jack up the car so that it is evenly off the ground. No one side should be higher than the rest. Once it’s off the ground remove all the four wheels so that you can access brake calipers.
Step 2: Next, loosen the cover of the brake fluid reservoir. With the help of vise grips, loosen the bleeder caps as well. Leave each of them just loose, but not too lose that it can leak out fluid.
Step 3: Now, begin working the wheels starting with the passenger rear wheel. Place one end of the plastic tubing over the bleeder. Raise the other end so that it stays above the fluid reservoir.
Side Note: it’s important that the tubing is positioned at a higher level than the reservoir to ensure thorough cleaning of air. You can secure it on the roof of the car or to the c-pillar using masking tape.
Step 4: Open the bleeder slowly using a wrench. The brake fluid should start rising in the clear plastic tubing. Observe carefully, you will see bubbles of air escaping. Meanwhile, the fluid will keep rising until it attains the same height as the fluid inside the reservoir. That should take anywhere between 3 and 5 minutes.
Step 5: Once you notice that there are no more air bubbles coming through the tubing, close the bleeder tightly and top off the fluid reservoir. Pull the tubing off the bleeder while holding the jar so that the fluid doesn’t spill.
Step 6: Work the remaining wheels in this order: driver rear, passenger front and finally driver front. In each case, repeat steps 3 all through 5.
Step 7: When all the brake lines are done start the car and step on the brake pedal to get its feel. It should be firm, not spongy. If it’s still spongy then it means the gravity bleeding didn’t work. You can either repeat the whole process or try a different method.
Note: monitor the brake fluid in the reservoir through the entire bleeding process. It should be full, or the maximum it can be at any given time. If the tank runs empty it will such in the air, and that will be the complete opposite of what you are trying to do.
How to Bleed Brakes with 2 People (Pump and Hold Method)
Have someone that can help you do the bleeding? Great! An extra pair of hands (and legs for this matter) might come in handy.
The person doesn’t necessarily need to know how to bleed brakes. They only need to be careful listeners, excellent communicators and have the ability to push the brake pedal.
Step 1: Lift the car with jacks and remove all four wheels. Open and remove the caps from each bleeder screw. As is the case with all other methods, do one wheel at a time in this order: passenger rear, driver rear, passenger front and finally driver front. Also, keep the reservoir full through the entire process.
Step 2: Place your wrench in position (on the bleeder) but don’t open the valve just yet. Instead, attach your clear tubing firmly over the valve then put the opposite end inside an empty bottle for collecting used fluid.
Step 3: Time to involve your partner. As them to enter the car and press the brake pedal 3 or 4 times and then hold it down as far as possible. Ask them not to release the pedal until you tell them to.
Step 4: Now it’s back to you. With the pedal held down, turn the bleeder valve through ¼ to release brake fluid and air. Close the valve (by tightening the screw) after 2 or 3 seconds. Your partner should feel the brake pedal move to the floor suddenly.
Step 5: When the screw is tightly in place, ask your partner to release the pedal. Repeat steps 3 and 4 until there are no more air bubbles visible in the plastic tubing.
Step 6: Do the same for the remaining wheels in the order listed in step 1. So you will move from the passenger rear to the driver rear and then the passenger front and finally the driver front wheel.
Step 7: Check the bleeder screws in each wheel to ensure that they are tightly in place. Also, inspect for signs of leaks on the bleeder screws. If there are none put the rubber caps back in place and then test the firmness of the brake pedal. It shouldn’t be spongy.
How to Bleed Brakes with ABS
Normal bleeding is usually enough to clear the ABS of air after replacement of wheel cylinders, calipers, lines, and hoses. That means you can use any one of the above methods and it will get the job done.
However, if you replace the master cylinder, high-pressure accumulator, ABS modulator or a component of the ABS modulator (like a valve or brake line) then the story changes completely.
In that case, you will need to perform a special procedure to clear the ABS of trapped air. The exact steps vary depending on the type of ABS. While some require the use of a scan tool, others don’t. Here are the procedures for bleeding some of the most common types of ABS.
1. How to Bleed Brakes with Delco ABS-VI
Cars that use the v system can be bled using any of the methods discussed above. However, before you start the bleeding process, you must ensure that the rear pistons in the ABS’s modulator are in the home position.
That means its check balls should be unseated. Otherwise, you won’t be able to perform bleeding on the rear lines. So how can you unseat the check balls?
There are two ways of doing that. The first involves using a scan tool while the second doesn’t require a scan tool.
If you have a scan tool, go to the F4 ABS Test Mode. From there, select F0 for manual control options. Go ahead and command the rear motor to push its pistons to the home position. When that is done you can now bleed the rear lines normally.
In case you don’t have a scan tool, start by opening the front bleeder screw of the ABS modulator. Note that a modulator has two of them, be sure to open the front one.
Now, bleed the modulator, close its screw and then bleed both front lines. Start with the right line followed by the left.
Drive the car with a speed of at least 3mph. By doing so the controller will automatically command the ABS to push the rear pistons to the home position. Once that’s done go ahead and bleed the rear lines normally.
2. How to Bleed Brakes with DBC-7
If your car is fitted with the DELPHI DBC-7 ABS then use a pressure bleeder and follow these steps:
Step 1: Connect your pressure bleeder to the car’s master cylinder reservoir
Step 2: Turn on the car’s ignition
Step 3: With all four bleeder screws still closed, crank up the pressure to 35psi
Step 4: On a scan tool, choose Automatic Bleed Procedure. The tool will automatically cycle and energize ABS solenoids in the BPMV for about one minute.
Step 5: The scan tool will ask you to perform bleeding for each wheel, one at a time. It will run the pump as well as release valve cycle for about one minute for each wheel. After doing that, the scan tool will do final cycling for about 20 seconds to expel any remaining air from the ABS.
Step 6: Disconnect the pressure pump, close the master cylinder and check the pedal to confirm that it is stiff and not spongy.
3. How to Bleed Brakes for Kelsey-Hayes 4WAL ABS
If you are only replacing the master cylinder, then bleed it before installing. That simple trick should do.
In case you haven’t replaced the front ABS valve you can bleed the brakes normally using either a pressure pump or vacuum pump. However, the sequence for bleeding should be:
- Master cylinder goes first
- Rear anti-lock valve comes second
- Combination valve is third
- Front anti-lock valve is fourth
- Left rear wheel comes fifth
- The right rear wheel is sixth
- Right front wheel follows
- Left front wheel comes last.
If you have replaced the front ABS valve then the bleeding procedure changes as well. In that case, follow these steps:
Step 1: Loosen the bleed plug on your new front valve. Make sure it’s loose enough (at least ¼ turn) to bleed both the lower and upper parts of the anti-lock valve
Step 2: Remove the cap from the bleed valve stem. In its place put the Valve Depressor Tool 6670. Make sure that you have slid the notched side of the 6670 tool snuggly onto the boss that surrounds the bleed valve stem. At the same time, ensure that the stem is held inward (open position) to allow full bleeding of the upper section of the new valve.
Step 3: Tighten the thumbscrew on the 6670 tool, but not too much. It should just be enough to push the valve stem inward by about 0.03 inches.
Step 4: Press the brake pedal 10 to 15 times in rapid successions. Doing that will fill both the upper and lower sections of the valve.
Step 5: Repeat the procedure for each new valve assembly at each brake line. Be sure to close the valve bleed plug before pressing the brake pedal. Also, keep bleeding until you see that the fluid flowing from a particular fitting is free of air bubbles.
Step 6: Now, remove the depressor tool from the valve stem and then close the valve with a cap.
Note: the above methods are for specific ABS systems. Always check the owner’s manual for instructions on how to bleed your car’s ABS brakes.
Do I Need To Bleed All 4 Brake Lines?
Not necessarily. However, there are conditions that call for bleeding all the four lines. They are:
- If your brake pedal feels spongy
- The amount of brake fluid in the reservoir has dropped drastically
- You removed, replaced or repaired the master cylinder
- Other repair works like replacing one wheel cylinder, single brake caliper, or one rubber hose don’t require bleeding all 4 lines. You can simply bleed the single line that was affected.
Is It Better to Bleed Brakes with Car On Or Off?
It is recommended that you bleed brakes with the car off. Why? Because the brake booster is largely controlled by the engine vacuum. This is a large diaphragm whose purpose is to multiply brake force.
That particular component should not be active during bleeding. Besides, the underbelly of a car has so many moving parts, including the axel. Leaving the car on keeps them moving and exposes you to the risk of accidents.
Do You Need to Bleed Brakes After Replacing Pads?
That depends on how the pads were replaced. If the bleeder valve was opened before squeezing the brake caliper back in when changing the brake pad then you need to bleed the system. It implies that the brake system was interfered with by opening the bleeder valve.
On the contrary, if the bleeder valves were not affected then you don’t need to bleed the brakes. That may be the case in some cars (especially Asian models) where the caliper can just be squeezed back in place using a clamp or wrench.
Having said that, it’s never a bad idea to bleed brakes. Regardless of how the pads (or calipers) were put in place, you can still bleed your brakes to ensure they work efficiently.
My Brakes Won’t Bleed, What Could Be The Problem?
There are many things that can make a car’s brakes fail to bleed. Here are the main ones:
- Master cylinder is not full. If the fluid level is too low air might make its way into the system during the bleeding process
- There’s a lot of air in the system. If the air trapped in the brake system is too much (in excess of 8%) one bleeding cycle may not be enough to clear. So repeat the process until the brake pedal stops feeling spongy.
- Blocked valves. Inspect bleeder valves carefully and thoroughly to ensure that none is blocked.
- Problematic master cylinder. The main issue is usually the piston. At times it fails it come back and suck fluid from the reservoir. You also need to check for that.
What Does It Cost to Bleed Brakes?
All the methods of how to bleed brakes can be done at home with little to no help from someone else. Even so, some people are not quite comfortable doing things the DIY way.
If you are one of them you may consider taking your car to the shop for brake bleeding. On average it will cost you between $100 and $125. Labor costs range from $85 to $110.
Bleeding the ABS is significantly costlier, especially if ABS sensors or the ABS module requires replacement. While sensors typically cost $100 to $200 each, the ABS module retails at $600 or more.
In short, depending on the extent of the damage, you may have to pay in excess of $1000 to get the ABS bled thoroughly and properly.