{"product_id":"whale-ak8050-service-kit-henderson-mk5-bilge-pump","title":"Whale AK8050 Service Kit | Henderson MK5 Bilge Pump","description":"\u003cp class=\"nvn-hero\"\u003eThe Whale AK8050 is the factory service kit for the Henderson MK5 universal bilge pump, part number BP0510. It's everything you need to bring a tired hand pump back to full stroke: a new diaphragm, inlet and outlet valves, the top cover seal, both sets of circlips, and a full set of M5 screws and nuts. One rebuild and you're pumping like new.\u003c\/p\u003e\n\n\u003cdiv class=\"nvn-description\"\u003e\n\u003cp\u003eThe Whale AK8050 is the complete service kit for the Henderson MK5 universal bilge pump, the one Whale sells under part number BP0510. If your manual bilge pump has gone soft on the stroke, started leaking around the cover, or just isn't moving the water it used to, this is the fix. You rebuild the wet end instead of buying a whole new pump. For a pump that's often bolted into a locker or bonded to the hull, that's the difference between an afternoon job and a much bigger one.\u003c\/p\u003e\n\u003cp\u003eEverything that wears out is in the box. You get a fresh diaphragm, a new inlet valve and inlet valve plate, a new outlet valve, and the top cover seal that keeps the whole thing from weeping. Whale includes the small parts that always seem to walk off during a rebuild too: two large circlips, two small circlips, four long valve screws, and a full set of eight M5 by 25 screws with eight matching M5 nuts. So you're not hunting through a parts drawer halfway through the job.\u003c\/p\u003e\n\u003cp\u003eThe rebuild itself is straightforward if you take your time. Pull the top cover, lift out the old diaphragm, and swap the inlet and outlet valves. The diaphragm is the heart of the pump, and a cracked or stiff one is usually why the pump lost its prime. Get the new valves seated flat and aligned before you close it up. We've seen diaphragms tear again within a couple of seasons when the valves weren't lined up right, so it's worth slowing down here. A light smear of waterproof grease on the seals helps them seat and makes the next rebuild easier.\u003c\/p\u003e\n\u003cp\u003eTwo things trip people up. The circlips are the first. They want to pop off on the first stroke if they aren't fully seated, so use a proper pair of circlip pliers and steady, even pressure until each one clicks home. Keep the spare small circlips close, because they're easy to launch across the bilge. The second is the top cover seal. That's the most common leak point after a rebuild, and it's almost always because the cover nuts got torqued unevenly and warped the cover. Snug the eight M5 nuts in a cross pattern, a little at a time, the same way you'd torque a wheel.\u003c\/p\u003e\n\u003cp\u003eThe kit also gives you fresh mounting hardware, which matters more than it sounds. M5 screws strip easily when they're run straight into a fiberglass mount, so pre-tap the holes and add a dab of thread locker on reassembly. Do that once and the pump stays put through years of pounding.\u003c\/p\u003e\n\u003cp\u003eThis kit fits the Henderson MK5 on both powerboats and sailboats, and it's a smart part of an annual maintenance plan if your bilge sees mud, silt, or oily water. Those bilges gum up the valve plates faster, and a yearly clean-and-rebuild keeps the pump ready for the day you actually need it. If you're already in there, it's worth checking the outlet hose and check valve at the same time, especially on a sailboat that spends time heeled over, where backflow through a tired valve is a real problem.\u003c\/p\u003e\n\u003cp\u003eOne note on fitment: this is the service kit for the MK5 version of the BP0510 pump. If you're not sure which generation of Whale Henderson pump you've got, check the casting on the body before you order, or send us the numbers and we'll confirm it. Get the right kit and the rebuild is genuinely satisfying. Bad pump in, good pump out, and you didn't have to unbolt the whole thing.\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eKey Features\u003c\/h2\u003e\n\u003cul class=\"nvn-features\"\u003e\n  \u003cli\u003eComplete wet-end rebuild kit for the Whale Henderson MK5 (BP0510) universal bilge pump\u003c\/li\u003e\n  \u003cli\u003eNew diaphragm restores full stroke and pumping capacity\u003c\/li\u003e\n  \u003cli\u003eFresh inlet valve, inlet valve plate, and outlet valve for reliable priming and no backflow\u003c\/li\u003e\n  \u003cli\u003eNew top cover seal stops the most common post-rebuild leak\u003c\/li\u003e\n  \u003cli\u003eTwo large and two small circlips included, the parts most often lost during a rebuild\u003c\/li\u003e\n  \u003cli\u003eFour long valve screws hold the valve assembly square and aligned\u003c\/li\u003e\n  \u003cli\u003eEight M5 x 25 screws and eight M5 nuts give you fresh, corrosion-free mounting hardware\u003c\/li\u003e\n  \u003cli\u003eRebuilds the pump in place, no need to replace the whole unit\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cdiv class=\"nvn-trust\"\u003e\n  \u003ch2\u003eWhy Buy from NVN Marine\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eAuthorized Whale Marine reseller, full manufacturer warranty\u003c\/li\u003e\n    \u003cli\u003eNMEA member and ABYC certified, advice from real boat techs\u003c\/li\u003e\n    \u003cli\u003eSame-day shipping before 3 PM ET on in-stock items\u003c\/li\u003e\n    \u003cli\u003eNY headquarters and Fort Lauderdale flagship retail store\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003cdiv class=\"nvn-faq\"\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhich pump does the Whale AK8050 fit?\u003c\/summary\u003e\n    \u003cp\u003eIt's the service kit for the Whale Henderson MK5 universal bilge pump, part number BP0510. It rebuilds that pump's wet end back to full performance.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat's included in the kit?\u003c\/summary\u003e\n    \u003cp\u003eA diaphragm, an inlet valve, an inlet valve plate, an outlet valve, a top cover seal, four long valve screws, two large circlips, two small circlips, eight M5 by 25 screws, and eight M5 nuts.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eDo I need any special tools to do the rebuild?\u003c\/summary\u003e\n    \u003cp\u003eA proper pair of circlip pliers is the one tool that makes life easier. The circlips need steady, even pressure to seat fully, and circlip pliers give you that control. Everything else is basic hand tools.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eHow often should I rebuild the pump?\u003c\/summary\u003e\n    \u003cp\u003eIf your bilge stays clean, every few seasons or whenever the stroke goes soft is fine. If it sees mud, silt, or oily water, plan on a yearly clean-and-rebuild because that grime gums up the valve plates faster.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhy did my old diaphragm tear?\u003c\/summary\u003e\n    \u003cp\u003eAge is the usual cause, but a diaphragm can also tear early if the valves weren't aligned flat during the last rebuild. Take your time seating the new valves and the diaphragm lasts a lot longer.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eMy rebuilt pump is leaking. Where do I look first?\u003c\/summary\u003e\n    \u003cp\u003eThe top cover seal is the most common leak point after a rebuild, and it usually comes from torquing the cover nuts unevenly and warping the cover. Snug the eight M5 nuts in a cross pattern, a little at a time.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eDoes this kit work on both powerboats and sailboats?\u003c\/summary\u003e\n    \u003cp\u003eYes. The Henderson MK5 is used on both, and this kit fits either install. On a sailboat that spends time heeled over, it's especially worth checking the outlet valve and check valve for backflow while you're in there.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eHow do I keep the M5 mounting screws from stripping?\u003c\/summary\u003e\n    \u003cp\u003eThey strip easily when run straight into a fiberglass mount. Pre-tap the holes and add a dab of thread locker on reassembly, and the pump stays put through years of pounding.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eShould I replace anything else while I have the pump apart?\u003c\/summary\u003e\n    \u003cp\u003eIt's a good time to check the outlet hose and check valve. If either is tired, replacing them now prevents backflow and saves you opening the pump up again soon.\u003c\/p\u003e\n  \u003c\/details\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\u003ctable class=\"nvn-specs\"\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n\u003cth\u003eTitle\u003c\/th\u003e\n\u003ctd\u003eWhale AK8050 Service Kit for Henderson MK5 Bilge Pump\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eBrand\u003c\/th\u003e\n\u003ctd\u003eWhale Marine\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eManufacturer Part Number\u003c\/th\u003e\n\u003ctd\u003eAK8050\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eUPC\u003c\/th\u003e\n\u003ctd\u003e766478805058\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eKit Type\u003c\/th\u003e\n\u003ctd\u003eService \/ rebuild kit\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eFits Pump\u003c\/th\u003e\n\u003ctd\u003eHenderson MK5 Universal Bilge Pump (BP0510)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eDiaphragm\u003c\/th\u003e\n\u003ctd\u003e1\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eInlet Valve\u003c\/th\u003e\n\u003ctd\u003e1\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eInlet Valve Plate\u003c\/th\u003e\n\u003ctd\u003e1\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eOutlet Valve\u003c\/th\u003e\n\u003ctd\u003e1\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eTop Cover Seal\u003c\/th\u003e\n\u003ctd\u003e1\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eLong Valve Screws\u003c\/th\u003e\n\u003ctd\u003e4\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eLarge Circlips\u003c\/th\u003e\n\u003ctd\u003e2\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eSmall Circlips\u003c\/th\u003e\n\u003ctd\u003e2\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eM5 x 25 Screws\u003c\/th\u003e\n\u003ctd\u003e8\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eM5 Nuts\u003c\/th\u003e\n\u003ctd\u003e8\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e\n{\n    \"@context\": \"https:\/\/schema.org\",\n    \"@type\": \"FAQPage\",\n    \"mainEntity\": [\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Which pump does the Whale AK8050 fit?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"It's the service kit for the Whale Henderson MK5 universal bilge pump, part number BP0510. It rebuilds that pump's wet end back to full performance.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"What's included in the kit?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"A diaphragm, an inlet valve, an inlet valve plate, an outlet valve, a top cover seal, four long valve screws, two large circlips, two small circlips, eight M5 by 25 screws, and eight M5 nuts.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Do I need any special tools to do the rebuild?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"A proper pair of circlip pliers is the one tool that makes life easier. The circlips need steady, even pressure to seat fully, and circlip pliers give you that control. Everything else is basic hand tools.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"How often should I rebuild the pump?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"If your bilge stays clean, every few seasons or whenever the stroke goes soft is fine. If it sees mud, silt, or oily water, plan on a yearly clean-and-rebuild because that grime gums up the valve plates faster.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Why did my old diaphragm tear?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Age is the usual cause, but a diaphragm can also tear early if the valves weren't aligned flat during the last rebuild. Take your time seating the new valves and the diaphragm lasts a lot longer.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"My rebuilt pump is leaking. Where do I look first?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"The top cover seal is the most common leak point after a rebuild, and it usually comes from torquing the cover nuts unevenly and warping the cover. Snug the eight M5 nuts in a cross pattern, a little at a time.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Does this kit work on both powerboats and sailboats?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Yes. The Henderson MK5 is used on both, and this kit fits either install. On a sailboat that spends time heeled over, it's especially worth checking the outlet valve and check valve for backflow while you're in there.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"How do I keep the M5 mounting screws from stripping?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"They strip easily when run straight into a fiberglass mount. Pre-tap the holes and add a dab of thread locker on reassembly, and the pump stays put through years of pounding.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Should I replace anything else while I have the pump apart?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"It's a good time to check the outlet hose and check valve. If either is tired, replacing them now prevents backflow and saves you opening the pump up again soon.\"\n            }\n        }\n    ]\n}\n\u003c\/script\u003e\n","brand":"Whale Marine","offers":[{"title":"Default Title","offer_id":45067798347869,"sku":"2008975","price":59.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0299\/7266\/0317\/files\/ImageServerAPI_24e5a596-06c8-4864-bffa-17a1ca9cf510.jpg?v=1789669823","url":"https:\/\/nvnmarine.com\/products\/whale-ak8050-service-kit-henderson-mk5-bilge-pump","provider":"NVN Marine","version":"1.0","type":"link"}