Tip & How-To about Cars & Trucks

How Do I Bleed the Brakes?

P { margin-bottom: 0.25cm; line-height: 120%; }a:link { } Bleeding brakes is pretty much the same across all vehicles. However, are you sure that there's air in the system and not a faulty brake master cylinder? The brake master cylinder has rubberised 'O' seals inside which, if worn, can cause a spongy pedal that has to be pumped before the brakes feel hard.

To bleed the brakes you need a length of plastic tube to fit onto the brake bleed nipple on the brake calliper. You can buy a brake bleeding kit which incorporates a non-return valve. The valve allows brake fluid to be pumped through it but prevents air from being drawn back up the tube into the brake system.


You can use ordinary plastic tube, but one end should be placed in a container of brake fluid to prevent air being drawn back in.


1. Locate the bleed nipple on each calliper. Usually you start at the front wheel furthest from the master cylinder, then the front wheel furthest from the master cylinder. The image below relates to a right hand drive UK car. USA left hand drive may be different. Check the correct sequence for your vehicle


2. Before you begin:Put a ring spanner onto the bleed nipple. Put a finger over the end of the bleed nipple to prevent air from entering via the nipple and 'rock' the spanner to make sure that the nipple will actually loosen. It is quite common for brake bleed ******* to seize then shear when turned with a spanner(wrench..). Don't use an open-ended spanner (wrench) otherwise the chances are you will 'round off' the bleed nipple.

3. Put the ring spanner on the bleed nipple and fit the bleed tube.
There is no need to start the engine. Get somebody to - slowly - depress the brake pedal. Undo the nipple slightly and brake fluid (maybe with air bubbles in it) should be visible in the tube.

When the pedal reaches bottom get your helper to hold the pedal down and tighten the bleed nipple. Let the brake pedal rise. The pedal should then be pressed again and held down - you open the bleed nipple as the pedal travels down and tighten it again whilst it is still held down. Repeat the process 5 times per calliper. Check the fluid level in the brake fluid reservoir after every 5 pumps on the pedal.

4. Most cars have a split-circuit braking system. That is, the front offside brake system is the same for the rear nearside. The rear nearside is in the same system as the front nearside. It's a safety feature, that's all.

In normal circumstances you only need to bleed the calliper that you have been working on. For example, you have just fitted a new calliper/rotor/pads to the front nearside - you only should have to bleed that calliper.



Plastic tube with non return valve for bleeding brake


Problems:
You've bled the brakes and the pedal is still soft. You wouldn't believe how common a problem this is. You're now reading about resetting ABS and changing all sorts of valves? The simple answer is you still have air in the system. And it can be damn difficult to shift.

Ok...
You've just changed your calliper(s) and no matter what, the pedal won't become hard. Maybe you've bled the brakes several times?

If you're going to fit a new calliper, first use clamps to squeeze the flexible hoses before removing the old callipers. This prevents a lot of air travelling back up into the pipework. Before you fit the new calliper remove the piston and undo the brake nipple. Pour brake fluid into the recess where the piston goes and swirl it around. Replace the piston and push it fully home. Then tighten the brake bleeder. Fit the calliper. You've excluded some air.

Fit the new brake disks (rotors)/callipers and use a couple of wheel nuts to pull it tight, into place. Then bleed that calliper. If the brake piston is slightly protruding it can allow air to become trapped behind it, and it's damn difficult to shift. You want that piston to be as fully in as it can be.

If, for example, you've fitted new front callipers, bled them and the pedal is still soft, you have to suspect air has found its way to the rear wheels - and you'll have to bleed the brakes in sequence.

  • Before removing any rotor or calliper- clamp the flexible brake hose
  • Remove new calliper piston and fill with brake fluid
If there's been no work carried out on the brakes and the pedal is soft - first check the brake fluid level in the master cylinder. If the level is ok and you have no leaks in the system - it's probably the master cylinder seals at fault.

If you've replaced callipers/ master cylinder and the brakes are still soft - there's air in the system. You have to keep re-bleeding.

To put things into context, I'm in the UK. I have a 1998 4 liter Jeep. I've just replaced the front callipers/disks (rotors) and have bled the brakes a whopping 8 times. The pedal is better, but still spongy. There's still air in the system. I forgot to clamp the flexible brake hoses before I started. Air has probably found its way into the rear wheel system.

And just as a point of interest, if your going to run your car up onto ramps:





Be careful ... at an angle with the engine ticking over your engine may be not be able to pick up oil from the crankcase. The results can be disastrous. Don't do it for more than a couple of minutes.



Below: Ring spanner on bleed nipple with tube attached. Always 'rock' the .spanner first to make sure that the nipple will loosen.










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1 Answer

Can you bleed the brakes system from the top of the brake line


Can you bleed the brakes system from the top of the brake line Rick, No! I will post links to proper bleeding procedures, if you can not do it this way, take it in to a qualified shop. Some vehicles need to use a scan tool during the bleeding process to cycle the pump and valves.
"I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info."
How To Bleed Your Brakes Feature

Bleeding Brakes

How to do Complete Brake Flush and Bleed

Mar 22, 2016 | Cars & Trucks

1 Answer

front line blow, replaced line master cly to abs block and from abs to right front wheel. bleed have very low and soft paddle.on 03 gmc 2500 hd 4x4. did not put all the turns and bends back in line does this have to be done.


Ok here is what you have to do. First off make sure your master cylinder is full, Second your vehicle must be running when you bleed brakes that is equiped with ABS this allows the ABS pump to to run you must bleed both front brakes starting at the passenger side wheel then moving to the drivers side. It will take quit a bit of bleeding and be sure to keep checking fluid level in master cylinder well bleeding. Just remeber the vehicle must be running while bleeding the brakes.

May 12, 2011 | Chevrolet 2500 Cars & Trucks

1 Answer

whats the proper way to bleed the breaks


Bleeding the Brake System (ABS) Auto Bleed Procedure NOTE: Perform a manual bleeding procedure. If the brake pedal height and firmness results are not achieved, perform the auto bleed procedure below.
  1. Raise and support the vehicle.
  2. Remove the tire and wheel assemblies.
  3. Inspect the battery state of charge.
  4. Install a scan tool.
  5. Turn ON the ignition, with the engine OFF.
  6. With the scan tool, establish communications with the ABS/TCS system. Select Special Functions from the ABS/TCS menu. Select Automated Bleed from the Special Functions menu.
  7. Bleed the base brake system.
  8. Follow the scan tool directions until the desired brake pedal height is achieved.
  9. If the bleed procedure is aborted, a malfunction exists. Perform the following steps before resuming the bleed procedure:
  10. If a DTC is detected, refer to Diagnostic Trouble Code (DTC) List and diagnose the appropriate DTC.
  11. If the brake pedal feels spongy, perform the conventional brake bleed procedure again.
  12. When the desired pedal height is achieved, press the brake pedal in order to inspect for firmness.
  13. Remove the scan tool.
  14. Install the tire and wheel assemblies.
  15. Inspect the brake fluid level.
  16. Road test the vehicle while inspecting that the pedal remains high and firm.
Bleeding ABS Automated Bleed Procedure NOTE: In most circumstances a base brake bleed is all that is required for most component replacements (such as wheel cylinders, calipers, brake tubes, and master cylinder) except for brake pressure modulator valve (BPMV) replacement.
The following automated antilock brake system (ABS) bleed procedure is required when one of the following occur:
  • Manual bleeding at the wheel cylinders does not achieve the desired pedal height or feel.
  • Replacement of the BPMV
  • Extreme loss of brake fluid has occurred.
  • Air ingestion is suspected.
NOTE: If none of the above conditions apply, use standard bleed procedures.
The auto bleed procedure is used on BOSH 5.3 equipped vehicles. This procedure uses a scan tool to cycle the system solenoid valves and run the pump in order to purge the air from the secondary circuits. These secondary circuits are normally closed off, and are only opened during system initialization at vehicle start up and during ABS operation. The automated bleed procedure opens these secondary circuits and allows any air trapped inside the BPMV to flow out toward the wheel cylinders or calipers where it can be purged out of the system.
Preliminary Inspection
  1. Inspect the battery for a full charge.
  2. Repair the battery and charging system as necessary.
  3. Connect a scan tool to the data link connector (DLC) and select the current and history DTCs.
  4. Repair any DTCs prior to performing the ABS bleed procedure.
  5. Inspect for visual damage and leaks and repair as needed.
Preliminary Setup
  1. Before servicing the vehicle refer to the precautions at the beginning of this section.
  2. Raise and support the vehicle.
  3. Turn the ignition switch to the OFF position.
  4. Remove all 4 tires (if necessary)
  5. Connect the pressure bleeding tool.
  6. Turn the ignition switch to RUN position with the engine off.
  7. Connect a scan tool and establish communications with the ABS system.
  8. Pressurize the bleeding tool to 30-35 psi (206-241 kPa).
Automated Bleed Procedure
NOTE: The Auto Bleed Procedure may be terminated at any time during the process by pressing the EXIT button. No further Scan Tool prompts pertaining to the Auto Bleed procedure will be given.
CAUTION
After exiting the bleed procedure, relieve bleed pressure and disconnect bleed equipment per manufacturers instructions. Failure to properly relieve pressure may result in spilled brake fluid causing damage to components and painted surfaces.
  1. With the pressure bleeding tool set to 30-35 psi (206-241 kPa) and all bleeder screws in closed position, select Automated Bleed Procedure on the scan tool and follow the instructions.
  2. The first part of the automated bleed procedure will cycle the pump and front release valves for one minute.
  3. After the cycling has stopped the scan tool will enter a "cool down" mode and display a 3 minute timer. NOTE: The auto bleed will not continue until this timer expired, and cannot be overridden.
  4. During the next step, the scan tool will request the technician to open one of the bleeder screws. The scan tool will then cycle the respective release valve and pump motor for 1 minute.
  5. The scan tool will repeat step 3 for the remaining bleeder screws.
  6. With the bleeder tool still attached to the vehicle and maintaining 30-35 psi (206-241 kPa), the scan tool will instruct the technician to independently open each bleeder screw for approximately 20 seconds. This should allow any remaining air to be purged from the brake lines.
  7. When the automated bleed procedure is completed the scan tool will display the appropriate message.
  8. Install all 4 tires, if necessary.
  9. Remove the pressure from the pressure bleeding tool
  10. Disconnect the tool from the vehicle.
  11. Depress the brake pedal to gauge pedal height and feel.
  12. Repeat the procedure until the pedal is acceptable.
  13. Remove the scan tool from the DLC connector.
  14. Safely lower the vehicle.
  15. Inspect the brake fluid level in master cylinder.
  16. Road test the vehicle while ensuring the brake pedal remains high and firm.
  17. If the vehicle is equipped with a traction control system (TCS), the scan tool will cycle both the ABS and TCS solenoids valves. This bleed procedure is the same as above.
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Sep 18, 2010 | 1998 Oldsmobile Silhouette

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