{"id":29114,"date":"2019-10-14T04:00:52","date_gmt":"2019-10-14T08:00:52","guid":{"rendered":"http:\/\/www.dodgegarage.com\/news-api\/?p=29114"},"modified":"2024-03-25T11:23:58","modified_gmt":"2024-03-25T15:23:58","slug":"bleeding-out","status":"publish","type":"post","link":"https:\/\/test.api.dodgegarage.com\/news\/how-to\/2019\/10\/bleeding-out.html","title":{"rendered":"Bleeding Out"},"content":{"rendered":"\n

How to purge the air out of braking systems.<\/em><\/h2>\n\n\n\n

When a routine brake job is performed (pads\nand\/or shoes, and maybe the rotors\/drums, are replaced), the\nbrake system should be bled to remove any residual air in the brake\nlines. In most cases, very little, if any, air will be present. That\nlikely means that the hydraulic system is not opened to allow air to\nenter into it.<\/p>\n\n\n\n

When a brake system repair requires that the\nhydraulic system be opened, air will enter the system. This air must be purged.\nExamples of such repairs include replacing the caliper and\/or wheel cylinder,\ninstalling a new master system and replacing the ABS accumulator. Failure to\npurge, or bleed, this air from the hydraulic system can result in a soft,\nspongy brake pedal feel and reduced braking performance.<\/p>\n\n\n\n

ABS Braking Basics<\/strong><\/h1>\n\n\n\n

Under normal braking conditions (dry roads, normal\nspeeds), the ABS (antilock brake system) functions the same as\na standard base brake system with a diagonally split master cylinder\nand conventional vacuum assist (also known as power brakes). The brake\npedal is pushed and the hydraulic pressure is applied equally at each\nwheel to stop the vehicle.<\/p>\n\n\n\n

ABS mode is activated when the locking tendency for\none or more wheels is detected during application of the brakes (meaning\none or more wheels will lock when braking on ice or snow). During ABS\nbraking, the hydraulic pressure is not the same; rather, it is regulated\nto prevent any wheel from locking. The Hydraulic Control Unit (HCU)\ncontrols the flow of brake fluid using a series of valves and\naccumulators. The pressure is regulated by the Integrated Control\nUnit (ICU). (The HCU is commonly known as the accumulator and is part\nof the ICU.)<\/p>\n\n\n\n

The system can build and release hydraulic pressure\nat each wheel, depending on the signals generated by the Wheel Speed\nSensor (WSS) at each wheel and received at the Antilock Brake Module\n(ABM). In the days before ABS, this buildup and release of hydraulic\npressure was accomplished by the driver pumping the brake pedal pump furiously\nand repeatedly. The ABS is doing the same thing (pumping the brake\npedal), except it is being done much faster than humanly possible.<\/p>\n\n\n\n

In a nutshell, that is how the ABS works. And, as is\nthe case with a base brake system (no ABS), air in the HCU will prevent\nproper, and safe, braking performance. It should be noted, though, when\nthe HCU is replaced, the entire brake system must be bled because the\nbrake system has now been opened and air has been allowed in.<\/p>\n\n\n\n

Bleeding the ABS<\/strong><\/h1>\n\n\n\n

Brake systems with ABS must be bled as two\nindependent braking systems. The non-ABS portion of the brake\nsystem (base system) with ABS should be bled the same way as any\nnon-ABS braking system. The ABS portion of the brake system must be bled\nseparately.<\/p>\n\n\n\n

NOTE: During the brake bleeding procedure, be sure\nthat the brake fluid level remains close to the FULL level in the master\ncylinder fluid reservoir; check the fluid level periodically during the\nbleeding procedure; add Mopar\u00ae<\/sub> DOT 3 brake fluid as required.<\/em><\/p>\n\n\n\n

When bleeding the ABS, the following sequence of\nsteps must be followed to ensure complete and adequate bleeding.\nFirst, make sure all hydraulic fluid lines are installed and properly\ntorqued. Then, connect the scan tool to the diagnostics (OBDII) connector.\nCheck to be sure there are no stored fault codes for the ABM. Next, attach\na clear tube (1) to the bleeder screw on the first wheel to be\nbled. Submerge the end of the tube in a clear container (2)\nfilled with clean brake fluid, as shown in Figure 1<\/strong>.<\/p>\n\n\n\n

Figure 1 \u2013 Tube connected to the\nbleed screw<\/strong><\/p>\n\n\n\n

Bleed the base brake system. Pressure bleeding is recommended to ensure all air has been purged from the system. Manual bleeding can also be utilized, but additional time will be required. The brakes should be bled in the following sequence:<\/p>\n\n\n\n

\"diagram<\/figure><\/div>\n\n\n\n
  1. Left\n rear wheel<\/li>
  2. Right\n front wheel<\/li>
  3. Right\n rear wheel<\/li>
  4. Left\n front wheel<\/li><\/ol>\n\n\n\n

    If\npressure builds when bleeding the base system, attach the fluid hose from\nthe pressure bleeder (2) to the special cap (1) on the master cylinder (3)\n(see Figure 2<\/strong>). Open the bleeder screw at least one full turn\nto obtain a steady stream of brake fluid. After approximately 4-8 ounces\nof brake fluid has been bled, close the bleeder screw.<\/p>\n\n\n\n

    NOTE:\nBe sure the flow of brake fluid is free of air before closing the bleed\nscrew.<\/em><\/p>\n\n\n\n

    Figure\n2 \u2013 Pressure bleeder<\/strong><\/p>\n\n\n\n

    \"diagram<\/figure><\/div>\n\n\n\n

    Check and adjust the brake fluid level to the FULL mark on the reservoir before proceeding to bleed the next wheel. Bleed all four wheels, then check the feel of the brake pedal. It should be solid. If the feel is spongy or soft, air is still present.<\/p>\n\n\n\n

    If the brakes are being bled manually, have a\nhelper pump the brake pedal three or four times, then hold down the\nbrake pedal. Open the bleeder screw. When the brake pedal\ndrops, close the bleeder screw. Release the brake pedal. Repeat this\nstep until all the air is removed from that wheel circuit. Check\nand adjust the brake fluid level. Bleed the remaining three wheels in\nthe same manner. Check the feel of the brake pedal. It should be solid.\nIf the feel is spongy or soft, air is still present.<\/p>\n\n\n\n

    After\nbleeding the base brake system, bleed the ABS portion of the brake system.\nFor discussion purposes, the specific vehicle being referenced is a 2012\nminivan. Check the service manual for the vehicle being repaired for\nspecific scan tool displays. Using the scan tool, select ECU VIEW, then\nselect ABS MISCELLANEOUS FUNCTIONS to access the bleeding procedures.\nFollow the instructions displayed on the scan tool. When finished bleeding\nthe ABS system, disconnect the scan tool.<\/p>\n\n\n\n

    NOTE:\nThe ABS section of the brake system cannot be bled without the use of the\nscan tool; there are no manual procedures for bleeding the HCU.<\/em><\/p>\n\n\n\n

    With\nthe ABS bleeding completed, bleed the base brake system a second time\nusing the same procedures that were outlined for bleeding the base brake\nsystem the first time. Once again, check the fluid level in the master\ncylinder and be sure that it is at the FULL level.<\/p>\n\n\n\n

    To\ncomplete the brake bleeding procedures, test drive the vehicle to check\nthe brake performance. The brakes should operate properly and the brake\npedal should feel firm, not soft or spongy. If some sponginess is\ndetected, repeat the bleeding procedure.<\/p>\n","protected":false},"excerpt":{"rendered":"

    How to purge the air out of braking systems. When a routine brake job is performed (pads and\/or shoes, and maybe the rotors\/drums, are replaced), the brake system should be bled to remove any residual air in the brake lines. In most cases, very little, if any, air will be present. That likely means that the hydraulic system is not opened to allow air to enter into it. When a brake system repair requires that the hydraulic system be opened, air will enter the system. This air must be purged. […]<\/p>\n","protected":false},"author":27,"featured_media":29134,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[639],"tags":[1778],"class_list":["post-29114","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-how-to","tag-maintenance"],"acf":[],"custom_fields":{"post_thumbnail_image":"https:\/\/test.api.dodgegarage.com\/news\/wp-content\/uploads\/2019\/10\/feature-12.jpg","icon_selection":"article","external_link":"","featured_article":[],"upload_background_image":""},"_links":{"self":[{"href":"https:\/\/test.api.dodgegarage.com\/news\/wp-json\/wp\/v2\/posts\/29114"}],"collection":[{"href":"https:\/\/test.api.dodgegarage.com\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/test.api.dodgegarage.com\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/test.api.dodgegarage.com\/news\/wp-json\/wp\/v2\/users\/27"}],"replies":[{"embeddable":true,"href":"https:\/\/test.api.dodgegarage.com\/news\/wp-json\/wp\/v2\/comments?post=29114"}],"version-history":[{"count":12,"href":"https:\/\/test.api.dodgegarage.com\/news\/wp-json\/wp\/v2\/posts\/29114\/revisions"}],"predecessor-version":[{"id":29146,"href":"https:\/\/test.api.dodgegarage.com\/news\/wp-json\/wp\/v2\/posts\/29114\/revisions\/29146"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/test.api.dodgegarage.com\/news\/wp-json\/wp\/v2\/media\/29134"}],"wp:attachment":[{"href":"https:\/\/test.api.dodgegarage.com\/news\/wp-json\/wp\/v2\/media?parent=29114"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/test.api.dodgegarage.com\/news\/wp-json\/wp\/v2\/categories?post=29114"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/test.api.dodgegarage.com\/news\/wp-json\/wp\/v2\/tags?post=29114"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}