{"product_id":"sierra-18-3904-marine-piston-ring-set-for-johnson-evinrude-omc-85-300-hp-outboards-replaces-omc-394930-3-5-in-bore-standard","title":"Sierra 18-3904 Standard Piston Rings, OMC 394930 Cross Reference, V-4\/V-6 60 Degree Eagle Series","description":"\u003cp\u003eThe Sierra 18-3904 is a standard-size piston ring set engineered for OMC V-4 and V-6 60 Degree Eagle Series outboard and Sea Drive engines. Each ring is precision machined to restore proper cylinder sealing, compression, and oil control on a rebuild or overhaul, helping the engine run efficiently and preventing blow-by that leads to power loss and excess oil consumption. As a standard (STD.) size ring set, part number 18-3904 is intended for cylinders that have not been bored oversize; if a block has been bored out, a corresponding oversize ring set is required instead. Sierra manufactures these rings to correspond with the original equipment specification, and every set is backed by Sierra's standard parts warranty. This part is sold as a compact, lightweight ring set suited to marine mechanics and engine builders performing a piston ring replacement or full piston kit rebuild on qualifying OMC 60 Degree Eagle Series powerheads and Sea Drive applications.\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 18-3904\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Name:\u003c\/strong\u003e Piston Rings\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRing Size:\u003c\/strong\u003e Standard (STD.)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFinish:\u003c\/strong\u003e Machined\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.08 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Dimensions:\u003c\/strong\u003e 0.39 x 0.39 x 0.39 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 030999316981\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e OMC 394930\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eOMC V-4 and V-6 60 Degree Eagle Series outboard engines\u003c\/li\u003e\n\u003cli\u003eOMC Sea Drive engines\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eOMC 394930\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-3904 piston ring set fit?\u003c\/strong\u003e The Sierra 18-3904 is designed for OMC V-4 and V-6 60 Degree Eagle Series outboard engines as well as OMC Sea Drive engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs 18-3904 a standard size or oversize ring set?\u003c\/strong\u003e Part number 18-3904 is a standard (STD.) size piston ring set, meaning it is intended for cylinders at original bore diameter that have not been machined oversize.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-3904 cross reference to an OMC part number?\u003c\/strong\u003e Yes, the Sierra 18-3904 ring set corresponds to OMC part number 394930.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-3904 piston ring set weigh?\u003c\/strong\u003e The 18-3904 piston ring set weighs 0.08 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat are the dimensions of the Sierra 18-3904 piston rings?\u003c\/strong\u003e Sierra 18-3904 measures 0.39 x 0.39 x 0.39 inches per the packaged listing.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat finish do the 18-3904 piston rings have?\u003c\/strong\u003e The rings in Sierra part 18-3904 have a machined finish.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhen would I need an oversize ring set instead of 18-3904?\u003c\/strong\u003e If the cylinder bore on the OMC 60 Degree Eagle Series or Sea Drive block has been machined oversize during a rebuild, an oversize ring set is needed rather than the standard-size 18-3904.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3904 genuine Sierra manufactured or a generic aftermarket part?\u003c\/strong\u003e 18-3904 is manufactured by Sierra, a recognized marine parts brand, and is covered by Sierra's parts warranty.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included when I order part 18-3904?\u003c\/strong\u003e Ordering 18-3904 gets you the complete standard-size piston ring set for one piston on the applicable OMC 60 Degree Eagle Series or Sea Drive engine.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan 18-3904 be used for a full engine rebuild?\u003c\/strong\u003e Yes, the 18-3904 standard ring set is commonly installed during a piston or engine rebuild on OMC V-4\/V-6 60 Degree Eagle Series and Sea Drive engines, alongside the corresponding piston.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988169830619,"sku":"SIE-18-3904","price":36.39,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/18-3904__85667.1558321433.500.750.jpg?v=1785188628","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-3904-marine-piston-ring-set-for-johnson-evinrude-omc-85-300-hp-outboards-replaces-omc-394930-3-5-in-bore-standard","provider":"Good Vibes Marina","version":"1.0","type":"link"}