{"product_id":"performance-water-pump-kit-for-hummer-h2-2003-2005-6-0l","title":"Performance Water Pump Kit for Hummer H2 (2003-2005) 6.0L","description":"\u003ch2 style=\"font-size: clamp(18px, 3vw, 21px); margin-bottom: 15px; line-height: 1.3;\"\u003eHeavy-Duty Cooling Service Kit for 2003-2005 Hummer H2 (GMT257)\u003c\/h2\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhat it Does:\u003c\/strong\u003e The Performance Water Pump Kit completely restores coolant circulation and front-end accessory drive tension on the 2003-2005 Hummer H2 to eliminate overheating under heavy load and prevent catastrophic belt failure.\u003c\/p\u003e\n\n\u003ch3\u003eThe Stock Hummer H2 Cooling and Drive Belt Weakness\u003c\/h3\u003e\n\u003cp\u003eThe factory cooling system on the \u003cstrong\u003eGMT257\u003c\/strong\u003e platform works under extreme thermal strain due to the vehicle's 6,400-lb curb weight and frontal aerodynamic drag. Over time, the factory mechanical water pump bearing wears, causing the internal impeller shaft seal to weep coolant from the cavity vent hole. Concurrently, factory stamped-steel serpentine tensioner springs lose dampening tension from heat cycling, allowing belt oscillation, belt slip, and inadequate coolant flow at high ambient temperatures. Worn bearing runout can cause total accessory drive lockup and sudden engine heat soak on the cast-iron \u003cstrong\u003eVortec 6000 LQ4\u003c\/strong\u003e block.\u003c\/p\u003e\n\n\u003ch3\u003eThe Engineering Solution\u003c\/h3\u003e\n\u003cp\u003eThis comprehensive service kit replaces critical wear points simultaneously. The water pump assembly features a precision-cast aluminum housing paired with a high-flow, corrosion-resistant impeller designed to minimize cavitation at high rpm. Heavy-duty dual-row bearings and hardened carbon-ceramic mechanical seals withstand severe radial loads from the cooling fan clutch. Paired with OE-grade spring-damped accessory and A\/C tensioner assemblies and fiber-reinforced multi-rib EPDM belts, this kit restores specified drive belt wrap angle, optimizes water jacket heat transfer, and maintains stable thermostat opening temperatures across all duty cycles.\u003c\/p\u003e\n\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003cdiv style=\"overflow-x: auto; margin-bottom: 20px;\"\u003e\n  \u003ctable width=\"100% style=\" border-collapse: collapse border: solid font-size: min-width:\u003e\n    \u003ctr style=\"background-color: #f9f9f9;\"\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eFitment\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003e2003-2005 Hummer H2\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eEngine \/ Chassis\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003e\n\u003cstrong\u003e6.0L Vortec LQ4 V8\u003c\/strong\u003e \/ \u003cstrong\u003eGMT257\u003c\/strong\u003e\n\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #f9f9f9;\"\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eStock Output\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003e316-325 hp \/ 360-365 lb-ft\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eReplaces OEM Part #\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003e\n\u003cstrong\u003e12580162\u003c\/strong\u003e, \u003cstrong\u003e12609719\u003c\/strong\u003e, \u003cstrong\u003e12560380\u003c\/strong\u003e, \u003cstrong\u003e12562458\u003c\/strong\u003e, \u003cstrong\u003e12703898\u003c\/strong\u003e, \u003cstrong\u003e19195104\u003c\/strong\u003e\n\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/table\u003e\n\u003c\/div\u003e\n\n\u003ch3\u003eCompatibility\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e2003 Hummer H2 Base Sport Utility 4-Door (6.0L V8 LQ4 Gas)\u003c\/li\u003e\n  \u003cli\u003e2004 Hummer H2 Base Sport Utility 4-Door (6.0L V8 LQ4 Gas)\u003c\/li\u003e\n  \u003cli\u003e2005 Hummer H2 Base Sport Utility 4-Door (6.0L V8 LQ4 Gas)\u003c\/li\u003e\n  \u003cli\u003e2005 Hummer H2 Base Crew Cab Pickup 4-Door (6.0L V8 LQ4 Gas)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003ch4\u003eDoes this fit the GMT257 H2?\u003c\/h4\u003e\n\u003cp\u003eYes, this is a direct fit for the 2003-2005 Hummer H2 equipped with the \u003cstrong\u003e6.0L Vortec LQ4\u003c\/strong\u003e engine.\u003c\/p\u003e\n\n\u003ch4\u003eDoes this kit require bleeding the cooling system during installation?\u003c\/h4\u003e\n\u003cp\u003eYes, full block evacuation and a thorough cooling system burp procedure are necessary to eliminate air pockets around the cylinder head steam vents.\u003c\/p\u003e\n\n\u003ch3\u003eThe Hummer Heavy-Duty Caliber\u003c\/h3\u003e\n\u003cp\u003eEngineered to handle the thermal demands of heavy payload hauling, steep off-camber crawls, and severe highway towing without compromising coolant system pressure integrity.\u003c\/p\u003e","brand":"VelocityMax","offers":[{"title":"Default Title","offer_id":67544685805816,"sku":"DS-ECV3KCS0B","price":193.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0800\/1290\/2648\/files\/performance-water-pump-kit-for-hummer-h2-2003-2005-6-0l-1.jpg?v=1790708873","url":"https:\/\/performancechiptuning.com\/products\/performance-water-pump-kit-for-hummer-h2-2003-2005-6-0l","provider":"Performance Chip Tuning","version":"1.0","type":"link"}