{"product_id":"sierra-18-0563-water-tube-rubber-seal-for-mercury-mariner-outboards-replaces-oem-26-36556","title":"Sierra 18-0563 Water Tube Rubber Seal - OEM 26-36556 for Mercury\/Mariner Outboard Motors","description":"\u003cp\u003eThe Sierra 18-0563 is a rubber water tube seal engineered for Mercury and Mariner outboard motor cooling systems. This small but essential seal fits over the water tube where it passes between the powerhead and the lower unit, maintaining a watertight connection so raw water can travel through the cooling passages without leaking or allowing air intrusion. A worn, cracked, or hardened water tube seal is a common cause of overheating and cooling system leaks on outboard motors, and replacing it is a routine part of a lower unit reinstall or water pump service.\u003c\/p\u003e\u003cp\u003eMade from rubber for a durable, flexible seal against the water tube, the 18-0563 is manufactured to match OEM dimensions and cross-references directly to Mercury Marine part 26-36556, so it installs as a direct replacement without modification. Its compact size (0.39 x 0.39 x 0.39 inches) and light weight make it an inexpensive, easy-to-stock spare for anyone performing water pump impeller replacement or lower unit maintenance on compatible Mercury\/Mariner outboards.\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 18-0563\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Category:\u003c\/strong\u003e Mercury Outboard Cooling System\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Rubber\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\u003eWeight:\u003c\/strong\u003e 0.01 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 030999874627\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross-Reference:\u003c\/strong\u003e Mercury Marine 26-36556\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cp\u003eFits Mercury\/Mariner outboard motors that use Mercury Marine water tube seal 26-36556.\u003c\/p\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e26-36556\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-0563 water tube seal fit?\u003c\/strong\u003e The Sierra 18-0563 is designed for Mercury and Mariner outboard motors that use Mercury Marine water tube seal 26-36556.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-0563 the same as Mercury part 26-36556?\u003c\/strong\u003e Yes, the Sierra 18-0563 cross-references directly to Mercury Marine part number 26-36556 and installs as a direct replacement.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material is the 18-0563 seal made from?\u003c\/strong\u003e It is made from rubber, which provides the flexibility needed to seal tightly around the water tube.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow big is the Sierra 18-0563 water tube seal?\u003c\/strong\u003e The seal measures 0.39 x 0.39 x 0.39 inches and weighs 0.01 pounds, making it a small, lightweight component.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhen should this water tube seal be replaced?\u003c\/strong\u003e The 18-0563 should be replaced when it is cracked, hardened, or leaking, and it is commonly replaced during a lower unit reinstall or water pump impeller service on Mercury\/Mariner outboards.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan a bad water tube seal cause overheating?\u003c\/strong\u003e Yes, a worn or damaged water tube seal like the 18-0563 replacement can allow air intrusion or coolant leakage that leads to overheating in the outboard cooling system.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-0563 an OEM or aftermarket part?\u003c\/strong\u003e The 18-0563 is an aftermarket seal manufactured by Sierra to the same specifications as Mercury Marine OEM part 26-36556.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-0563 come with installation hardware?\u003c\/strong\u003e No, the 18-0563 is the rubber water tube seal only; no additional hardware is included.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I know if I need the 18-0563 versus a different seal?\u003c\/strong\u003e Confirm your outboard uses Mercury Marine water tube seal 26-36556; the Sierra 18-0563 is the direct match for that part number.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-0563 seal reusable after removal?\u003c\/strong\u003e Water tube seals like the 18-0563 are generally replaced rather than reused once removed, since they can lose their sealing shape during disassembly.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988078768347,"sku":"SIE-18-0563","price":0.88,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-0563_lg__39830.1558120582.500.750.jpg?v=1785189034","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-0563-water-tube-rubber-seal-for-mercury-mariner-outboards-replaces-oem-26-36556","provider":"Good Vibes Marina","version":"1.0","type":"link"}