{"id":53767,"date":"2017-11-01T09:41:47","date_gmt":"2017-11-01T14:41:47","guid":{"rendered":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/?p=53767"},"modified":"2026-02-12T08:30:38","modified_gmt":"2026-02-12T16:30:38","slug":"1999-chevy-12-ton-silverado-4by4","status":"publish","type":"post","link":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/2017\/11\/1999-chevy-12-ton-silverado-4by4","title":{"rendered":"1999 Chevy 1\/2 ton Silverado 4by4"},"content":{"rendered":"<p><img decoding=\"async\" class=\"alignnone size-full wp-image-36637\" src=\"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/wp-content\/uploads\/2016\/09\/1999-chevy-z71.jpg\" alt=\"1999 Chevy Z71\" width=\"600\" height=\"229\" srcset=\"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/wp-content\/uploads\/2016\/09\/1999-chevy-z71.jpg 600w, https:\/\/www.freeautomechanic.com\/mechanic\/forum\/wp-content\/uploads\/2016\/09\/1999-chevy-z71-300x115.jpg 300w\" sizes=\"(max-width: 600px) 100vw, 600px\" \/><\/p>\n<p>What is the purpose of vacuum line attached to the rear end?<\/p>\n<hr \/>\n<h3>Differential Vent Tube<\/h3>\n<p>The vacuum line is a vent tube. This keeps the unit from building pressure internally. It also moves the point of entry above any perceived area of water exposure. For example, Suppose you were to back a boat into the water. The vent tube is positioned high enough not to allow water to enter into the differential that may now be under water.<\/p>\n<p><img decoding=\"async\" class=\"alignnone size-full wp-image-53897\" src=\"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/wp-content\/uploads\/2017\/10\/1999-chevy-differential-tube-diagram.gif\" alt=\"differential vent tube diagram\" width=\"320\" height=\"296\" \/><\/p>\n","protected":false},"excerpt":{"rendered":"<p>What is the purpose of vacuum line attached to the rear end? Differential Vent Tube The vacuum line is a vent tube. This keeps the unit from building pressure internally. It also moves the point of entry above any perceived area of water exposure. For example, Suppose you were to back a boat into the&hellip;&nbsp;<a href=\"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/2017\/11\/1999-chevy-12-ton-silverado-4by4\" rel=\"bookmark\">Read More &raquo;<span class=\"screen-reader-text\">1999 Chevy 1\/2 ton Silverado 4by4<\/span><\/a><\/p>\n","protected":false},"author":14216,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"neve_meta_sidebar":"","neve_meta_container":"","neve_meta_enable_content_width":"","neve_meta_content_width":0,"neve_meta_title_alignment":"","neve_meta_author_avatar":"","neve_post_elements_order":"","neve_meta_disable_header":"","neve_meta_disable_footer":"","neve_meta_disable_title":"","footnotes":""},"categories":[1,3],"tags":[20469,393,20467,20468],"class_list":["post-53767","post","type-post","status-publish","format-standard","hentry","category-auto-repair-questions","category-chevy","tag-differential-tube","tag-silverado","tag-vacuum-line","tag-vent-tube"],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v23.0 (Yoast SEO v27.4) - https:\/\/yoast.com\/product\/yoast-seo-premium-wordpress\/ -->\n<title>1999 Chevy 1\/2 ton Silverado 4by4 - FreeAutoMechanic Advice<\/title>\n<meta name=\"description\" content=\"The vacuum line is a vent tube. This keeps the unit from building pressure internally. It also moves the point of entry above any perceived\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/2017\/11\/1999-chevy-12-ton-silverado-4by4\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"1999 Chevy 1\/2 ton Silverado 4by4\" \/>\n<meta property=\"og:description\" content=\"The vacuum line is a vent tube. This keeps the unit from building pressure internally. It also moves the point of entry above any perceived\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/2017\/11\/1999-chevy-12-ton-silverado-4by4\" \/>\n<meta property=\"og:site_name\" content=\"FreeAutoMechanic Advice\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/freeautomechanic\" \/>\n<meta property=\"article:published_time\" content=\"2017-11-01T14:41:47+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2026-02-12T16:30:38+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/wp-content\/uploads\/2016\/09\/1999-chevy-z71.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"600\" \/>\n\t<meta property=\"og:image:height\" content=\"229\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"larrybarr\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"larrybarr\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 minute\" \/>\n<!-- \/ Yoast SEO Premium plugin. -->","yoast_head_json":{"title":"1999 Chevy 1\/2 ton Silverado 4by4 - FreeAutoMechanic Advice","description":"The vacuum line is a vent tube. This keeps the unit from building pressure internally. It also moves the point of entry above any perceived","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/2017\/11\/1999-chevy-12-ton-silverado-4by4","og_locale":"en_US","og_type":"article","og_title":"1999 Chevy 1\/2 ton Silverado 4by4","og_description":"The vacuum line is a vent tube. This keeps the unit from building pressure internally. It also moves the point of entry above any perceived","og_url":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/2017\/11\/1999-chevy-12-ton-silverado-4by4","og_site_name":"FreeAutoMechanic Advice","article_publisher":"https:\/\/www.facebook.com\/freeautomechanic","article_published_time":"2017-11-01T14:41:47+00:00","article_modified_time":"2026-02-12T16:30:38+00:00","og_image":[{"width":600,"height":229,"url":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/wp-content\/uploads\/2016\/09\/1999-chevy-z71.jpg","type":"image\/jpeg"}],"author":"larrybarr","twitter_card":"summary_large_image","twitter_misc":{"Written by":"larrybarr","Est. reading time":"1 minute"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/2017\/11\/1999-chevy-12-ton-silverado-4by4#article","isPartOf":{"@id":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/2017\/11\/1999-chevy-12-ton-silverado-4by4"},"author":{"name":"larrybarr","@id":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/#\/schema\/person\/443c2983b6d57de16e222a6791727bcb"},"headline":"1999 Chevy 1\/2 ton Silverado 4by4","datePublished":"2017-11-01T14:41:47+00:00","dateModified":"2026-02-12T16:30:38+00:00","mainEntityOfPage":{"@id":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/2017\/11\/1999-chevy-12-ton-silverado-4by4"},"wordCount":82,"commentCount":1,"publisher":{"@id":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/#organization"},"image":{"@id":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/2017\/11\/1999-chevy-12-ton-silverado-4by4#primaryimage"},"thumbnailUrl":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/wp-content\/uploads\/2016\/09\/1999-chevy-z71.jpg","keywords":["differential tube","silverado","vacuum line","vent tube"],"articleSection":["Auto Repair Questions","Chevy"],"inLanguage":"en-US","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/www.freeautomechanic.com\/mechanic\/forum\/2017\/11\/1999-chevy-12-ton-silverado-4by4#respond"]}]},{"@type":"WebPage","@id":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/2017\/11\/1999-chevy-12-ton-silverado-4by4","url":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/2017\/11\/1999-chevy-12-ton-silverado-4by4","name":"1999 Chevy 1\/2 ton Silverado 4by4 - FreeAutoMechanic Advice","isPartOf":{"@id":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/#website"},"primaryImageOfPage":{"@id":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/2017\/11\/1999-chevy-12-ton-silverado-4by4#primaryimage"},"image":{"@id":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/2017\/11\/1999-chevy-12-ton-silverado-4by4#primaryimage"},"thumbnailUrl":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/wp-content\/uploads\/2016\/09\/1999-chevy-z71.jpg","datePublished":"2017-11-01T14:41:47+00:00","dateModified":"2026-02-12T16:30:38+00:00","description":"The vacuum line is a vent tube. 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