{"product_id":"sierra-18-7157-o-ring-for-mercury-outboards-replaces-oem-25-25439","title":"Sierra O-Ring 18-7157 for MerCruiser Stern Drive Model I (1963)","description":"\u003cp\u003eThe Sierra 18-7157 is an O-Ring used in the stern drive assembly on MerCruiser Model I stern drives built in 1963. It seals mating surfaces within the drive unit to keep water out and lubricant in, protecting internal gearcase components from corrosion and contamination. As a direct-fit component for this specific stern drive model and year, it is intended for use during drive unit service, rebuilds, or seal replacement where the original O-ring has hardened, cracked, or lost its seal due to age and heat cycling.\u003c\/p\u003e\u003cp\u003eThis is a single O-ring, sold individually, and is identified by Sierra part number 18-7157. It is manufactured to fit the MerCruiser Model I stern drive within the serial number range 1534570 through 1684187. Installing the correct O-ring for this specific model and serial range helps ensure a proper seal and prevents water intrusion or lubricant loss in the drive unit.\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 18-7157\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eItem Type:\u003c\/strong\u003e O-Ring\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282259686\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.11 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUnit Count:\u003c\/strong\u003e 1 O-Ring\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFitment:\u003c\/strong\u003e MerCruiser Stern Drive Model I (1963), serial number 1534570 thru 1684187\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eMerCruiser Stern Drive Model I, 1963, serial number range 1534570 thru 1684187\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat is the Sierra 18-7157 used for?\u003c\/strong\u003e The Sierra 18-7157 is an O-Ring used within the stern drive assembly on a MerCruiser Model I stern drive to seal against water intrusion and lubricant loss.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhich MerCruiser models does the 18-7157 O-Ring fit?\u003c\/strong\u003e It fits the MerCruiser Stern Drive Model I built in 1963, within the serial number range 1534570 thru 1684187.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many O-rings come in one order?\u003c\/strong\u003e Each order of Sierra part number 18-7157 includes one O-ring.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-7157 a genuine Sierra part or aftermarket?\u003c\/strong\u003e The 18-7157 is a Sierra-branded O-ring, identified by Sierra's own part number 18-7157.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-7157 O-Ring weigh?\u003c\/strong\u003e The Sierra 18-7157 O-Ring weighs 0.11 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use the 18-7157 on a MerCruiser Model I outside the listed serial range?\u003c\/strong\u003e The 18-7157 is specified for MerCruiser Model I units within serial number range 1534570 thru 1684187; units outside that range are not confirmed to use this part.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-7157?\u003c\/strong\u003e The UPC for the Sierra 18-7157 O-Ring is 808282259686.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhen would I need to replace this O-ring?\u003c\/strong\u003e This O-ring should be replaced during stern drive service or rebuild on a MerCruiser Model I, or if the existing seal has hardened, cracked, or begun leaking.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-7157 include any other seals or gaskets?\u003c\/strong\u003e No, the 18-7157 order includes only the O-ring itself with no additional seals or gaskets.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-7157 O-Ring model-specific or a universal size?\u003c\/strong\u003e The 18-7157 is specified by Sierra for the MerCruiser Model I stern drive rather than as a universal O-ring size.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988364505307,"sku":"SIE-18-7157","price":3.87,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/18-7157__80261.1722351487.500.750.jpg?v=1785188482","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-7157-o-ring-for-mercury-outboards-replaces-oem-25-25439","provider":"Good Vibes Marina","version":"1.0","type":"link"}