{"product_id":"sierra-18-3320-water-pump-kit-for-mercruiser-mr-and-alpha-i-sterndrives-interchanges-glm-12120-and-mallory-9-48307","title":"Sierra 18-3320 Water Pump Kit for MerCruiser MR\/Alpha I, Serial 6854393 to 0D594568","description":"\u003cp\u003eThe Sierra 18-3320 Water Pump Kit is a replacement cooling system water pump kit built for MerCruiser MR\/Alpha I sterndrive units, covering serial numbers 6854393 through 0D594568. The kit is engineered to meet or exceed the quality of the original equipment pump it replaces, giving boat owners a direct, fit-specific way to restore cooling system performance without sourcing individual components separately. Because MR\/Alpha I lower units in this serial range share a common pump architecture, this kit is also the correct part for MerCruiser models that have been retro-fitted with an Alpha style lower unit lacking a pre-load pin in the top of the driveshaft, since those units must use Alpha style parts rather than the earlier housing-style components.\u003c\/p\u003e\u003cp\u003eThe kit is fit-specific to the listed serial number range, so boat owners should confirm their unit's serial number against the range before ordering to ensure proper fit. It is manufactured with glass-reinforced components for durability in the marine cooling environment and is sold under the Sierra brand as part number 18-3320.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3320\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Water Pump Kit\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Glass\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.98 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 030999315823\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFitment:\u003c\/strong\u003e MerCruiser MR\/Alpha I, serial numbers 6854393 to 0D594568\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInterchange Numbers:\u003c\/strong\u003e GLM 12120, Mallory 9-48307\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMerCruiser MR\/Alpha I sterndrive units, serial numbers 6854393 to 0D594568\u003c\/li\u003e\n\u003cli\u003eMerCruiser units retro-fitted with an Alpha style lower unit (no pre-load pin in top of driveshaft) must use Alpha style parts, including the 18-3320 water pump kit\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eGLM 12120\u003c\/li\u003e\n\u003cli\u003eMallory 9-48307\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-3320 Water Pump Kit fit?\u003c\/strong\u003e This kit fits MerCruiser MR\/Alpha I sterndrive units with serial numbers between 6854393 and 0D594568, and is fit-specific so the serial number should be confirmed before ordering.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs 18-3320 the correct pump for a MerCruiser unit retro-fitted with an Alpha style lower unit?\u003c\/strong\u003e Yes. MerCruiser units that have been retro-fitted with an Alpha style lower unit, meaning there is no pre-load pin in the top of the driveshaft, must use Alpha style parts, and the Sierra 18-3320 is one of the correct parts for that configuration.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM or aftermarket numbers cross-reference to the Sierra 18-3320?\u003c\/strong\u003e The Sierra 18-3320 Water Pump Kit is interchangeable with GLM 12120 and Mallory 9-48307.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-3320 water pump kit weigh?\u003c\/strong\u003e The Sierra 18-3320 Water Pump Kit weighs 0.98 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material is the Sierra 18-3320 water pump kit made from?\u003c\/strong\u003e The kit uses glass-reinforced material in its construction, per the Sierra 18-3320 product specifications.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill this water pump kit fit a MerCruiser with an older or newer serial number range than listed?\u003c\/strong\u003e No. The 18-3320 is fit-specific to MerCruiser MR\/Alpha I units in the serial range 6854393 to 0D594568; units outside that range require a different Sierra water pump part number.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-3320 meet original equipment quality standards?\u003c\/strong\u003e The kit is built to meet or exceed the quality of the original MerCruiser water pump component it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-3320 a complete water pump kit or individual parts?\u003c\/strong\u003e The Sierra 18-3320 is sold as a complete Water Pump Kit rather than a single individual component.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow can I be sure I am ordering the right water pump for my MerCruiser MR\/Alpha I unit?\u003c\/strong\u003e Check your MerCruiser drive unit's serial number against the range of 6854393 to 0D594568; the Sierra 18-3320 is fit-specific to that range, so matching the serial number is the way to confirm proper fit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs Mallory 9-48307 the same as the Sierra 18-3320?\u003c\/strong\u003e Mallory 9-48307 is a cross-referenced equivalent to the Sierra 18-3320 Water Pump Kit, along with GLM 12120.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat brand manufactures the 18-3320 water pump kit?\u003c\/strong\u003e The 18-3320 Water Pump Kit is manufactured under the Sierra brand.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988143485147,"sku":"SIE-18-3320","price":57.69,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/Untitled-1__31712.1753840720.500.750.jpg?v=1785188041","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-3320-water-pump-kit-for-mercruiser-mr-and-alpha-i-sterndrives-interchanges-glm-12120-and-mallory-9-48307","provider":"Good Vibes Marina","version":"1.0","type":"link"}