{"id":7320,"date":"2026-06-17T03:40:33","date_gmt":"2026-06-17T03:40:33","guid":{"rendered":"http:\/\/australianholden.com\/?p=7320"},"modified":"2026-06-21T12:40:11","modified_gmt":"2026-06-21T12:40:11","slug":"hq-hj-hx-hz-and-wb-holden-cooling-system-problems","status":"publish","type":"post","link":"https:\/\/australianholden.com\/index.php\/2026\/06\/17\/hq-hj-hx-hz-and-wb-holden-cooling-system-problems\/","title":{"rendered":"HQ, HJ, HX, HZ and WB Holden Cooling System Problems"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The HQ, HJ, HX, HZ and WB Holden range is renowned for its durability. Whether fitted with a Holden 202 six-cylinder, a 253 V8, a 308 V8 or even a Chevrolet conversion, these cars earned a reputation for reliability that helped make them some of Australia&#8217;s best-selling vehicles.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">However, one area that frequently causes problems today is the cooling system.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">When these cars were new, Australian roads were different. Traffic was lighter, fuel quality was different, and few owners expected their Holden to spend hours crawling through modern traffic on a 40-degree summer day. Fast forward 40 to 50 years and ageing cooling components, internal corrosion and increased engine wear have made overheating one of the most common complaints among HQ-WB owners.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The good news is that most cooling system issues are well understood and relatively straightforward to diagnose.<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">Why Cooling Problems Are Common<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">Several factors contribute to cooling issues in HQ-WB Holdens.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Common Causes<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Original radiators reaching end of life<\/li>\n\n\n\n<li>Internal rust buildup<\/li>\n\n\n\n<li>Worn water pumps<\/li>\n\n\n\n<li>Old hoses<\/li>\n\n\n\n<li>Blocked engine water jackets<\/li>\n\n\n\n<li>Inefficient factory fan systems<\/li>\n\n\n\n<li>Poor maintenance history<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Most overheating problems are caused by several small issues rather than a single catastrophic failure.<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">Blocked Radiators<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">Radiator blockage is one of the most common causes of overheating.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Symptoms<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Temperature rises during driving<\/li>\n\n\n\n<li>Engine runs hot in traffic<\/li>\n\n\n\n<li>Cool spots on radiator core<\/li>\n\n\n\n<li>Overflow bottle loss<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Causes<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Internal corrosion<\/li>\n\n\n\n<li>Mineral deposits<\/li>\n\n\n\n<li>Old coolant contamination<\/li>\n\n\n\n<li>Decades of sediment buildup<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Many original radiators are now more than 40 years old and simply cannot dissipate heat effectively.<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">Best Radiator Upgrade<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\">Recommended Product: Aluminium Performance Radiator<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Benefits<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Improved cooling capacity<\/li>\n\n\n\n<li>Better heat transfer<\/li>\n\n\n\n<li>Lighter weight<\/li>\n\n\n\n<li>Corrosion resistance<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Best For<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Daily driven classics<\/li>\n\n\n\n<li>Towing applications<\/li>\n\n\n\n<li>V8-powered Holdens<\/li>\n\n\n\n<li>Summer driving<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Modern aluminium radiators are one of the most effective cooling upgrades available.<\/p>\n\n\n<div id=\"fu_ebay_0\"><!-- Presentation: cols = 4, rows = 2, slideshow = Manual, slides = 3, slideId = 0 --><div class=\"fu_ebay_results_container \">\n<h5 class=\"fu_ebay_results_title\" style=\"display: block !important;\">\n<a name=\"fu_slidetop_0\"><\/a><a href=\"https:\/\/www.ebay.com.au\/?mkcid=1&#038;mkrid=705-53470-19255-0&#038;siteid=15&#038;campid=5339152561&#038;customid=5339151688&#038;toolid=10049&#038;mkevt=1\" class=\"fu_ebay\" style=\"display:inline !important;\" rel=\"nofollow\" target=\"_blank\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" src=\"https:\/\/i0.wp.com\/australianholden.com\/wp-content\/plugins\/fast-ebay-listings\/US\/Right_Now_108x45.gif?resize=108%2C45&#038;ssl=1\" style=\"border:0;display:block !important;\" width=\"108\" height=\"45\" alt=\"Right Now on eBay\"\/><\/a>&nbsp;HQ HJ HX HZ WB aluminium radiator<\/h5>\nLoading&#8230;<\/div>\n<\/div>\n<script>\n<!--\nvar content_fu_ebay_0 = null;\nvar waitForDepends_fu_ebay_0 = setInterval(function () {\n  if (typeof jQuery !== \"undefined\") {\n  if (window.fu_is_bot_useragent !== undefined) {\n    clearInterval(waitForDepends_fu_ebay_0);\n    if (typeof jQuery.ajax == \"undefined\") {\n      console.log(\"Fast eBay Listings: jQuery.ajax missing. Are you using jQuery.Slim that doesn't include ajax? \");\n      return;\n    }\n    if (fu_is_bot_useragent) return;\n    content_fu_ebay_0 = jQuery(\"#fu_ebay_0\");\n    jQuery(document).ready(jQuery.ajax({\n      type : \"post\",\n      url : \"https:\/\/australianholden.com\/wp-admin\/admin-ajax.php\",\n      data : {\n        action : \"fu_ebay_load_search\",\nfuDisableAPICache : 0,\nfuTraceLogging : 0,\nebay_country : \"AU\",\nfu_ebay_customId : \"\",\nfu_ebay_widget : 0,\nfu_ebay_picwidth : 225,\nfu_ebay_arrangement : 0,\nfu_ebay_title : \"HQ HJ HX HZ WB aluminium radiator\",\nfu_ebay_query : \"HQ HJ HX HZ WB aluminium radiator\",\nfu_ebay_searchInDesc : 0,\nfu_ebay_searchLocation : \"Internationally\",\nfu_ebay_pickupPostcode : \"\",\nfu_ebay_pickupRadius : 0,\nfu_ebay_sort : \"BestMatch\",\nfu_ebay_categoryIds : \"6030\",\nfu_ebay_sellers : \"\",\nfu_ebay_sellerType : \"\",\nfu_ebay_buyingOptions : \"\",\nfu_ebay_conditionOptions : \"\",\nfu_ebay_minPrice : 0,\nfu_ebay_maxPrice : 0,\nfu_ebay_minBids : 0,\nfu_ebay_maxBids : 0,\nfu_cols : 4,\nfu_rows : 2,\nfu_slideshow : \"Manual\",\nfu_slides : 3,\nfu_slideId : 0,\n\n      },\n      success : function( response ) {\n        content_fu_ebay_0.html( response );\n      },\n      error: function(e) {\n        console.log(\"Fast eBay Listings: deferred loading error: \" + e);\n      }\n    }));\n  }}\n}, 10);\n\/\/-->\n<\/script>\n\n\n\n<h1 class=\"wp-block-heading\">Internal Engine Rust<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">Many HQ-WB Holdens spent years running plain water rather than coolant.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Symptoms<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Brown coolant<\/li>\n\n\n\n<li>Poor heater performance<\/li>\n\n\n\n<li>Recurring overheating<\/li>\n\n\n\n<li>Rust flakes in cooling system<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Causes<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Lack of corrosion inhibitors<\/li>\n\n\n\n<li>Long-term storage<\/li>\n\n\n\n<li>Neglected maintenance<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Internal rust can significantly restrict coolant flow throughout the engine block.<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">Thermostat Failure<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">The thermostat regulates coolant flow between the engine and radiator.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Symptoms<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Rapid overheating<\/li>\n\n\n\n<li>Temperature fluctuations<\/li>\n\n\n\n<li>Engine taking too long to warm up<\/li>\n\n\n\n<li>Inconsistent gauge readings<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Common Causes<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Age-related failure<\/li>\n\n\n\n<li>Corrosion<\/li>\n\n\n\n<li>Sediment buildup<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">A thermostat is inexpensive but can create major problems when it fails.<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">Best Thermostat Replacement<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\">Recommended Product: Tridon High Flow Thermostat<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Benefits<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Reliable temperature control<\/li>\n\n\n\n<li>Improved coolant flow<\/li>\n\n\n\n<li>Quality Australian brand<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Best For<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Routine maintenance<\/li>\n\n\n\n<li>Cooling system rebuilds<\/li>\n\n\n\n<li>Performance applications<\/li>\n<\/ul>\n\n\n<div id=\"fu_ebay_1\"><!-- Presentation: cols = 4, rows = 2, slideshow = Manual, slides = 3, slideId = 1 --><div class=\"fu_ebay_results_container \">\n<h5 class=\"fu_ebay_results_title\" style=\"display: block !important;\">\n<a name=\"fu_slidetop_1\"><\/a><a href=\"https:\/\/www.ebay.com.au\/?mkcid=1&#038;mkrid=705-53470-19255-0&#038;siteid=15&#038;campid=5339152561&#038;customid=5339151688&#038;toolid=10049&#038;mkevt=1\" class=\"fu_ebay\" style=\"display:inline !important;\" rel=\"nofollow\" target=\"_blank\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" src=\"https:\/\/i0.wp.com\/australianholden.com\/wp-content\/plugins\/fast-ebay-listings\/US\/Right_Now_108x45.gif?resize=108%2C45&#038;ssl=1\" style=\"border:0;display:block !important;\" width=\"108\" height=\"45\" alt=\"Right Now on eBay\"\/><\/a>&nbsp;Tridon<\/h5>\nLoading&#8230;<\/div>\n<\/div>\n<script>\n<!--\nvar content_fu_ebay_1 = null;\nvar waitForDepends_fu_ebay_1 = setInterval(function () {\n  if (typeof jQuery !== \"undefined\") {\n  if (window.fu_is_bot_useragent !== undefined) {\n    clearInterval(waitForDepends_fu_ebay_1);\n    if (typeof jQuery.ajax == \"undefined\") {\n      console.log(\"Fast eBay Listings: jQuery.ajax missing. Are you using jQuery.Slim that doesn't include ajax? \");\n      return;\n    }\n    if (fu_is_bot_useragent) return;\n    content_fu_ebay_1 = jQuery(\"#fu_ebay_1\");\n    jQuery(document).ready(jQuery.ajax({\n      type : \"post\",\n      url : \"https:\/\/australianholden.com\/wp-admin\/admin-ajax.php\",\n      data : {\n        action : \"fu_ebay_load_search\",\nfuDisableAPICache : 0,\nfuTraceLogging : 0,\nebay_country : \"AU\",\nfu_ebay_customId : \"\",\nfu_ebay_widget : 0,\nfu_ebay_picwidth : 225,\nfu_ebay_arrangement : 0,\nfu_ebay_title : \"Tridon\",\nfu_ebay_query : \"Tridon thermostat Holden 202 253 308\",\nfu_ebay_searchInDesc : 0,\nfu_ebay_searchLocation : \"Internationally\",\nfu_ebay_pickupPostcode : \"\",\nfu_ebay_pickupRadius : 0,\nfu_ebay_sort : \"BestMatch\",\nfu_ebay_categoryIds : \"6030\",\nfu_ebay_sellers : \"\",\nfu_ebay_sellerType : \"\",\nfu_ebay_buyingOptions : \"\",\nfu_ebay_conditionOptions : \"\",\nfu_ebay_minPrice : 0,\nfu_ebay_maxPrice : 0,\nfu_ebay_minBids : 0,\nfu_ebay_maxBids : 0,\nfu_cols : 4,\nfu_rows : 2,\nfu_slideshow : \"Manual\",\nfu_slides : 3,\nfu_slideId : 1,\n\n      },\n      success : function( response ) {\n        content_fu_ebay_1.html( response );\n      },\n      error: function(e) {\n        console.log(\"Fast eBay Listings: deferred loading error: \" + e);\n      }\n    }));\n  }}\n}, 10);\n\/\/-->\n<\/script>\n\n\n\n<h1 class=\"wp-block-heading\">Worn Water Pumps<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">The water pump is responsible for circulating coolant through the engine.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Symptoms<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Coolant leaks from pump<\/li>\n\n\n\n<li>Bearing noise<\/li>\n\n\n\n<li>Overheating at idle<\/li>\n\n\n\n<li>Reduced coolant circulation<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Causes<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Bearing wear<\/li>\n\n\n\n<li>Seal failure<\/li>\n\n\n\n<li>Corrosion damage<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Many original pumps have been replaced multiple times throughout the vehicle&#8217;s life.<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">Best Water Pump Upgrade<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\">Recommended Product: GMB Water Pump<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Benefits<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>OEM-quality reliability<\/li>\n\n\n\n<li>Excellent flow rates<\/li>\n\n\n\n<li>Durable bearing design<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Best For<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Holden six-cylinder engines<\/li>\n\n\n\n<li>Holden V8 engines<\/li>\n\n\n\n<li>Long-term reliability<\/li>\n<\/ul>\n\n\n<div id=\"fu_ebay_2\"><!-- Presentation: cols = 4, rows = 2, slideshow = Manual, slides = 3, slideId = 2 --><div class=\"fu_ebay_results_container \">\n<h5 class=\"fu_ebay_results_title\" style=\"display: block !important;\">\n<a name=\"fu_slidetop_2\"><\/a><a href=\"https:\/\/www.ebay.com.au\/?mkcid=1&#038;mkrid=705-53470-19255-0&#038;siteid=15&#038;campid=5339152561&#038;customid=5339151688&#038;toolid=10049&#038;mkevt=1\" class=\"fu_ebay\" style=\"display:inline !important;\" rel=\"nofollow\" target=\"_blank\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" src=\"https:\/\/i0.wp.com\/australianholden.com\/wp-content\/plugins\/fast-ebay-listings\/US\/Right_Now_108x45.gif?resize=108%2C45&#038;ssl=1\" style=\"border:0;display:block !important;\" width=\"108\" height=\"45\" alt=\"Right Now on eBay\"\/><\/a>&nbsp;GMB<\/h5>\nLoading&#8230;<\/div>\n<\/div>\n<script>\n<!--\nvar content_fu_ebay_2 = null;\nvar waitForDepends_fu_ebay_2 = setInterval(function () {\n  if (typeof jQuery !== \"undefined\") {\n  if (window.fu_is_bot_useragent !== undefined) {\n    clearInterval(waitForDepends_fu_ebay_2);\n    if (typeof jQuery.ajax == \"undefined\") {\n      console.log(\"Fast eBay Listings: jQuery.ajax missing. Are you using jQuery.Slim that doesn't include ajax? \");\n      return;\n    }\n    if (fu_is_bot_useragent) return;\n    content_fu_ebay_2 = jQuery(\"#fu_ebay_2\");\n    jQuery(document).ready(jQuery.ajax({\n      type : \"post\",\n      url : \"https:\/\/australianholden.com\/wp-admin\/admin-ajax.php\",\n      data : {\n        action : \"fu_ebay_load_search\",\nfuDisableAPICache : 0,\nfuTraceLogging : 0,\nebay_country : \"AU\",\nfu_ebay_customId : \"\",\nfu_ebay_widget : 0,\nfu_ebay_picwidth : 225,\nfu_ebay_arrangement : 0,\nfu_ebay_title : \"GMB\",\nfu_ebay_query : \"GMB water pump Holden 202 253 308\",\nfu_ebay_searchInDesc : 0,\nfu_ebay_searchLocation : \"Internationally\",\nfu_ebay_pickupPostcode : \"\",\nfu_ebay_pickupRadius : 0,\nfu_ebay_sort : \"BestMatch\",\nfu_ebay_categoryIds : \"6030\",\nfu_ebay_sellers : \"\",\nfu_ebay_sellerType : \"\",\nfu_ebay_buyingOptions : \"\",\nfu_ebay_conditionOptions : \"\",\nfu_ebay_minPrice : 0,\nfu_ebay_maxPrice : 0,\nfu_ebay_minBids : 0,\nfu_ebay_maxBids : 0,\nfu_cols : 4,\nfu_rows : 2,\nfu_slideshow : \"Manual\",\nfu_slides : 3,\nfu_slideId : 2,\n\n      },\n      success : function( response ) {\n        content_fu_ebay_2.html( response );\n      },\n      error: function(e) {\n        console.log(\"Fast eBay Listings: deferred loading error: \" + e);\n      }\n    }));\n  }}\n}, 10);\n\/\/-->\n<\/script>\n\n\n\n<h1 class=\"wp-block-heading\">Fan Clutch Failure<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">Vehicles fitted with viscous fan clutches often suffer cooling issues when the clutch wears.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Symptoms<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Overheating in traffic<\/li>\n\n\n\n<li>Improved cooling at highway speeds<\/li>\n\n\n\n<li>Excessive fan freewheeling<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Causes<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Silicone fluid loss<\/li>\n\n\n\n<li>Internal wear<\/li>\n\n\n\n<li>Age deterioration<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">This is a particularly common issue on V8-powered cars.<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">Fan Shroud Problems<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">A surprising number of HQ-WB Holdens are missing their original fan shrouds.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Symptoms<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Overheating while stationary<\/li>\n\n\n\n<li>Poor airflow through radiator<\/li>\n\n\n\n<li>Increased engine temperatures at idle<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Why It Matters<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The fan shroud directs airflow through the radiator core. Without it, cooling efficiency drops significantly.<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">Best Cooling Fan Upgrade<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\">Recommended Product: Davies Craig Thermatic Electric Fan Kit<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Benefits<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Improved low-speed cooling<\/li>\n\n\n\n<li>Reduced engine load<\/li>\n\n\n\n<li>Adjustable operation<\/li>\n\n\n\n<li>Modern reliability<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Best For<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Modified vehicles<\/li>\n\n\n\n<li>Summer driving<\/li>\n\n\n\n<li>Traffic-heavy use<\/li>\n<\/ul>\n\n\n<div id=\"fu_ebay_3\"><!-- Presentation: cols = 4, rows = 2, slideshow = Manual, slides = 3, slideId = 3 --><div class=\"fu_ebay_results_container \">\n<h5 class=\"fu_ebay_results_title\" style=\"display: block !important;\">\n<a name=\"fu_slidetop_3\"><\/a><a href=\"https:\/\/www.ebay.com.au\/?mkcid=1&#038;mkrid=705-53470-19255-0&#038;siteid=15&#038;campid=5339152561&#038;customid=5339151688&#038;toolid=10049&#038;mkevt=1\" class=\"fu_ebay\" style=\"display:inline !important;\" rel=\"nofollow\" target=\"_blank\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" src=\"https:\/\/i0.wp.com\/australianholden.com\/wp-content\/plugins\/fast-ebay-listings\/US\/Right_Now_108x45.gif?resize=108%2C45&#038;ssl=1\" style=\"border:0;display:block !important;\" width=\"108\" height=\"45\" alt=\"Right Now on eBay\"\/><\/a>&nbsp;Davies Craig Thermatic Electric Fan Kit<\/h5>\nLoading&#8230;<\/div>\n<\/div>\n<script>\n<!--\nvar content_fu_ebay_3 = null;\nvar waitForDepends_fu_ebay_3 = setInterval(function () {\n  if (typeof jQuery !== \"undefined\") {\n  if (window.fu_is_bot_useragent !== undefined) {\n    clearInterval(waitForDepends_fu_ebay_3);\n    if (typeof jQuery.ajax == \"undefined\") {\n      console.log(\"Fast eBay Listings: jQuery.ajax missing. Are you using jQuery.Slim that doesn't include ajax? \");\n      return;\n    }\n    if (fu_is_bot_useragent) return;\n    content_fu_ebay_3 = jQuery(\"#fu_ebay_3\");\n    jQuery(document).ready(jQuery.ajax({\n      type : \"post\",\n      url : \"https:\/\/australianholden.com\/wp-admin\/admin-ajax.php\",\n      data : {\n        action : \"fu_ebay_load_search\",\nfuDisableAPICache : 0,\nfuTraceLogging : 0,\nebay_country : \"AU\",\nfu_ebay_customId : \"\",\nfu_ebay_widget : 0,\nfu_ebay_picwidth : 225,\nfu_ebay_arrangement : 0,\nfu_ebay_title : \"Davies Craig Thermatic Electric Fan Kit\",\nfu_ebay_query : \"Davies Craig Thermatic Electric Fan Kit\",\nfu_ebay_searchInDesc : 0,\nfu_ebay_searchLocation : \"Internationally\",\nfu_ebay_pickupPostcode : \"\",\nfu_ebay_pickupRadius : 0,\nfu_ebay_sort : \"BestMatch\",\nfu_ebay_categoryIds : \"6030\",\nfu_ebay_sellers : \"\",\nfu_ebay_sellerType : \"\",\nfu_ebay_buyingOptions : \"\",\nfu_ebay_conditionOptions : \"\",\nfu_ebay_minPrice : 0,\nfu_ebay_maxPrice : 0,\nfu_ebay_minBids : 0,\nfu_ebay_maxBids : 0,\nfu_cols : 4,\nfu_rows : 2,\nfu_slideshow : \"Manual\",\nfu_slides : 3,\nfu_slideId : 3,\n\n      },\n      success : function( response ) {\n        content_fu_ebay_3.html( response );\n      },\n      error: function(e) {\n        console.log(\"Fast eBay Listings: deferred loading error: \" + e);\n      }\n    }));\n  }}\n}, 10);\n\/\/-->\n<\/script>\n\n\n\n<h1 class=\"wp-block-heading\">Collapsed Radiator Hoses<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">Old radiator hoses can collapse internally even if they look fine externally.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Symptoms<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Intermittent overheating<\/li>\n\n\n\n<li>Coolant flow restriction<\/li>\n\n\n\n<li>Hose flattening at higher RPM<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Causes<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Age<\/li>\n\n\n\n<li>Internal deterioration<\/li>\n\n\n\n<li>Weak reinforcement springs<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Hoses should be considered maintenance items rather than lifetime components.<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">Head Gasket Problems<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">Persistent overheating can eventually damage the head gasket.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Symptoms<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Coolant loss<\/li>\n\n\n\n<li>White exhaust smoke<\/li>\n\n\n\n<li>Milky engine oil<\/li>\n\n\n\n<li>Cooling system pressure build-up<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Causes<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Previous overheating<\/li>\n\n\n\n<li>Corrosion<\/li>\n\n\n\n<li>Cylinder head distortion<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Fortunately, Holden sixes and V8s generally tolerate heat better than many modern engines.<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">Best Cooling System Flush<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\">Recommended Product: Nulon Radiator Flush<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Benefits<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Removes rust deposits<\/li>\n\n\n\n<li>Cleans cooling passages<\/li>\n\n\n\n<li>Improves coolant flow<\/li>\n\n\n\n<li>Reduces operating temperatures<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Best For<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Neglected cooling systems<\/li>\n\n\n\n<li>Preventative maintenance<\/li>\n\n\n\n<li>Cooling system restoration<\/li>\n<\/ul>\n\n\n<div id=\"fu_ebay_4\"><!-- Presentation: cols = 4, rows = 2, slideshow = Manual, slides = 3, slideId = 4 --><div class=\"fu_ebay_results_container \">\n<h5 class=\"fu_ebay_results_title\" style=\"display: block !important;\">\n<a name=\"fu_slidetop_4\"><\/a><a href=\"https:\/\/www.ebay.com.au\/?mkcid=1&#038;mkrid=705-53470-19255-0&#038;siteid=15&#038;campid=5339152561&#038;customid=5339151688&#038;toolid=10049&#038;mkevt=1\" class=\"fu_ebay\" style=\"display:inline !important;\" rel=\"nofollow\" target=\"_blank\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" src=\"https:\/\/i0.wp.com\/australianholden.com\/wp-content\/plugins\/fast-ebay-listings\/US\/Right_Now_108x45.gif?resize=108%2C45&#038;ssl=1\" style=\"border:0;display:block !important;\" width=\"108\" height=\"45\" alt=\"Right Now on eBay\"\/><\/a>&nbsp;Nulon<\/h5>\nLoading&#8230;<\/div>\n<\/div>\n<script>\n<!--\nvar content_fu_ebay_4 = null;\nvar waitForDepends_fu_ebay_4 = setInterval(function () {\n  if (typeof jQuery !== \"undefined\") {\n  if (window.fu_is_bot_useragent !== undefined) {\n    clearInterval(waitForDepends_fu_ebay_4);\n    if (typeof jQuery.ajax == \"undefined\") {\n      console.log(\"Fast eBay Listings: jQuery.ajax missing. Are you using jQuery.Slim that doesn't include ajax? \");\n      return;\n    }\n    if (fu_is_bot_useragent) return;\n    content_fu_ebay_4 = jQuery(\"#fu_ebay_4\");\n    jQuery(document).ready(jQuery.ajax({\n      type : \"post\",\n      url : \"https:\/\/australianholden.com\/wp-admin\/admin-ajax.php\",\n      data : {\n        action : \"fu_ebay_load_search\",\nfuDisableAPICache : 0,\nfuTraceLogging : 0,\nebay_country : \"AU\",\nfu_ebay_customId : \"\",\nfu_ebay_widget : 0,\nfu_ebay_picwidth : 225,\nfu_ebay_arrangement : 0,\nfu_ebay_title : \"Nulon\",\nfu_ebay_query : \"Nulon radiator flush\",\nfu_ebay_searchInDesc : 0,\nfu_ebay_searchLocation : \"Internationally\",\nfu_ebay_pickupPostcode : \"\",\nfu_ebay_pickupRadius : 0,\nfu_ebay_sort : \"BestMatch\",\nfu_ebay_categoryIds : \"6030\",\nfu_ebay_sellers : \"\",\nfu_ebay_sellerType : \"\",\nfu_ebay_buyingOptions : \"\",\nfu_ebay_conditionOptions : \"\",\nfu_ebay_minPrice : 0,\nfu_ebay_maxPrice : 0,\nfu_ebay_minBids : 0,\nfu_ebay_maxBids : 0,\nfu_cols : 4,\nfu_rows : 2,\nfu_slideshow : \"Manual\",\nfu_slides : 3,\nfu_slideId : 4,\n\n      },\n      success : function( response ) {\n        content_fu_ebay_4.html( response );\n      },\n      error: function(e) {\n        console.log(\"Fast eBay Listings: deferred loading error: \" + e);\n      }\n    }));\n  }}\n}, 10);\n\/\/-->\n<\/script>\n\n\n\n<h1 class=\"wp-block-heading\">Incorrect Coolant Use<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">Many owners continue using plain water.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Problems Caused<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Internal corrosion<\/li>\n\n\n\n<li>Reduced boiling protection<\/li>\n\n\n\n<li>Increased scale formation<\/li>\n\n\n\n<li>Water pump wear<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Modern coolant offers significant protection that early Holdens never received when new.<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">Best Coolant for HQ-WB Holdens<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\">Recommended Product: Penrite Classic Car Coolant<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Benefits<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Corrosion protection<\/li>\n\n\n\n<li>Compatible with older engines<\/li>\n\n\n\n<li>Long service life<\/li>\n\n\n\n<li>Suitable for brass and copper radiators<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Best For<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Original cooling systems<\/li>\n\n\n\n<li>Restorations<\/li>\n\n\n\n<li>Daily driven classics<\/li>\n<\/ul>\n\n\n<div id=\"fu_ebay_5\"><!-- Presentation: cols = 4, rows = 2, slideshow = Manual, slides = 3, slideId = 5 --><div class=\"fu_ebay_results_container \">\n<h5 class=\"fu_ebay_results_title\" style=\"display: block !important;\">\n<a name=\"fu_slidetop_5\"><\/a><a href=\"https:\/\/www.ebay.com.au\/?mkcid=1&#038;mkrid=705-53470-19255-0&#038;siteid=15&#038;campid=5339152561&#038;customid=5339151688&#038;toolid=10049&#038;mkevt=1\" class=\"fu_ebay\" style=\"display:inline !important;\" rel=\"nofollow\" target=\"_blank\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" src=\"https:\/\/i0.wp.com\/australianholden.com\/wp-content\/plugins\/fast-ebay-listings\/US\/Right_Now_108x45.gif?resize=108%2C45&#038;ssl=1\" style=\"border:0;display:block !important;\" width=\"108\" height=\"45\" alt=\"Right Now on eBay\"\/><\/a>&nbsp;Penrite Classic Car Coolant<\/h5>\nLoading&#8230;<\/div>\n<\/div>\n<script>\n<!--\nvar content_fu_ebay_5 = null;\nvar waitForDepends_fu_ebay_5 = setInterval(function () {\n  if (typeof jQuery !== \"undefined\") {\n  if (window.fu_is_bot_useragent !== undefined) {\n    clearInterval(waitForDepends_fu_ebay_5);\n    if (typeof jQuery.ajax == \"undefined\") {\n      console.log(\"Fast eBay Listings: jQuery.ajax missing. Are you using jQuery.Slim that doesn't include ajax? \");\n      return;\n    }\n    if (fu_is_bot_useragent) return;\n    content_fu_ebay_5 = jQuery(\"#fu_ebay_5\");\n    jQuery(document).ready(jQuery.ajax({\n      type : \"post\",\n      url : \"https:\/\/australianholden.com\/wp-admin\/admin-ajax.php\",\n      data : {\n        action : \"fu_ebay_load_search\",\nfuDisableAPICache : 0,\nfuTraceLogging : 0,\nebay_country : \"AU\",\nfu_ebay_customId : \"\",\nfu_ebay_widget : 0,\nfu_ebay_picwidth : 225,\nfu_ebay_arrangement : 0,\nfu_ebay_title : \"Penrite Classic Car Coolant\",\nfu_ebay_query : \"Penrite Classic Car Coolant\",\nfu_ebay_searchInDesc : 0,\nfu_ebay_searchLocation : \"Internationally\",\nfu_ebay_pickupPostcode : \"\",\nfu_ebay_pickupRadius : 0,\nfu_ebay_sort : \"BestMatch\",\nfu_ebay_categoryIds : \"6030\",\nfu_ebay_sellers : \"\",\nfu_ebay_sellerType : \"\",\nfu_ebay_buyingOptions : \"\",\nfu_ebay_conditionOptions : \"\",\nfu_ebay_minPrice : 0,\nfu_ebay_maxPrice : 0,\nfu_ebay_minBids : 0,\nfu_ebay_maxBids : 0,\nfu_cols : 4,\nfu_rows : 2,\nfu_slideshow : \"Manual\",\nfu_slides : 3,\nfu_slideId : 5,\n\n      },\n      success : function( response ) {\n        content_fu_ebay_5.html( response );\n      },\n      error: function(e) {\n        console.log(\"Fast eBay Listings: deferred loading error: \" + e);\n      }\n    }));\n  }}\n}, 10);\n\/\/-->\n<\/script>\n\n\n\n<h1 class=\"wp-block-heading\">Common Cooling System Mistakes<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\">Replacing Parts Without Flushing the System<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">New components quickly become contaminated by old rust deposits.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Ignoring Temperature Gauge Changes<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Small increases often indicate developing problems.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Running Without a Fan Shroud<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">This dramatically reduces cooling performance.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Using Plain Water<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">This remains one of the biggest causes of internal corrosion.<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">Recommended Cooling System Reliability Package<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">For HQ, HJ, HX, HZ and WB Holdens, the best cooling system upgrade package includes:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Aluminium radiator<\/li>\n\n\n\n<li>Tridon thermostat<\/li>\n\n\n\n<li>GMB water pump<\/li>\n\n\n\n<li>Davies Craig electric fan kit<\/li>\n\n\n\n<li>Penrite Classic Car Coolant<\/li>\n\n\n\n<li>Nulon cooling system flush<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">This combination addresses nearly every common cooling problem found in ageing Holdens.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Cooling system issues are among the most common problems facing HQ, HJ, HX, HZ and WB Holdens today. Fortunately, these systems are simple, parts remain widely available and most faults are relatively easy to diagnose.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The biggest mistake owners make is assuming overheating is normal for an old Holden. In reality, a properly maintained HQ-WB cooling system should comfortably handle Australian conditions, even on hot summer days.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">By addressing radiator efficiency, coolant flow, fan performance and corrosion prevention, these classic Holdens can remain reliable and enjoyable for decades to come.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">If you&#8217;re experiencing temperature problems, don&#8217;t ignore them. Most major engine failures begin with minor cooling system issues that were left unresolved.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Related Articles<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"https:\/\/australianholden.com\/index.php\/2026\/06\/17\/hq-hj-hx-hz-and-wb-holden-rust-problems\/\" type=\"post\" id=\"7316\">HQ HJ HX HZ WB Holden Rust Problems<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/australianholden.com\/index.php\/2026\/06\/20\/holden-202-engine-issues-explained\/\" type=\"post\" id=\"7311\">Holden 202 Engine Issues Explained<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/australianholden.com\/index.php\/2026\/06\/16\/holden-253-308-v8-issues-explained\/\" type=\"post\" id=\"7340\">Holden 308 V8 Issues Explained<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/australianholden.com\/index.php\/2026\/06\/17\/how-to-inspect-a-hq-hj-hx-hz-or-wb-holden-before-buying\/\" type=\"post\" id=\"7318\">How to Inspect a HQ HJ HX HZ WB Holden Before Buying<\/a><\/li>\n\n\n\n<li>Best Coolants for Classic Holdens<\/li>\n\n\n\n<li><a href=\"https:\/\/australianholden.com\/index.php\/2026\/06\/17\/hq-hj-hx-hz-and-wb-holden-electrical-problems\/\" type=\"post\" id=\"7332\">HQ HJ HX HZ WB Holden Electrical Problems<\/a><\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The HQ, HJ, HX, HZ and WB Holden range is renowned for its durability. Whether fitted with a Holden 202 six-cylinder, a 253 V8, a 308 V8 or even a Chevrolet conversion, these cars earned a reputation for reliability that helped make them some of Australia&#8217;s best-selling vehicles. However, one area that frequently causes problems [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":3471,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_uf_show_specific_survey":0,"_uf_disable_surveys":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":false},"categories":[1],"tags":[],"class_list":["post-7320","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.7 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>HQ, HJ, HX, HZ and WB Holden Cooling System 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