{"product_id":"circulating-water-pump-for-mercruiser-4-3l-v6-replaces-46-879194401-sierra-18-3506-1","title":"Sierra Circulating Pump 18-3506-1, Replaces 46-879194401, for MerCruiser V6 4.3L MCM SN 1A063240 and Newer","description":"\u003cp\u003eThe Sierra 18-3506-1 circulating pump is a direct-fit replacement water circulating pump built for MerCruiser V6 MCM engines, serial number 1A063240 (2007) and newer, on 4.3L engines without a water bypass hole. It uses a bi-directional brass impeller paired with a stainless steel shaft and stainless steel backing plate, giving the pump strong resistance to corrosion in the marine cooling system. The pump housing is designed to work with both stamped steel and composite timing covers, so it fits the timing cover configurations used across this engine family.\u003c\/p\u003e\u003cp\u003eEvery pump is inspected for fit, form, and function to dimensional standards before it ships, and each unit is finished with a vacuum test to confirm the seal holds properly. Mounting gaskets are included with the pump, so no separate gasket purchase is needed to complete the installation. This makes the 18-3506-1 a straightforward like-for-like swap for the factory circulating pump on qualifying MerCruiser 4.3L engines.\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 18-3506-1\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Circulating Pump\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Metal\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eImpeller:\u003c\/strong\u003e Bi-directional brass impeller\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eShaft Material:\u003c\/strong\u003e Stainless steel\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBacking Plate Material:\u003c\/strong\u003e Stainless steel\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTiming Cover Compatibility:\u003c\/strong\u003e Stamped steel and composite\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIncluded Components:\u003c\/strong\u003e Circulating pump with mounting gaskets\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 10.69 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eVehicle Service Type:\u003c\/strong\u003e Boat\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eQuality Testing:\u003c\/strong\u003e Vacuum tested for seal integrity, inspected for fit, form, and function\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMerCruiser V6 MCM, serial number 1A063240 (2007) and newer\u003c\/li\u003e\n\u003cli\u003e4.3L engines without a water bypass hole\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e46-879194401\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-3506-1 circulating pump fit?\u003c\/strong\u003e It fits MerCruiser V6 MCM engines with serial number 1A063240 (2007) and newer, specifically 4.3L engines without a water bypass hole.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part number does the 18-3506-1 replace?\u003c\/strong\u003e This pump replaces MerCruiser OEM number 46-879194401.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill this pump work on a 4.3L engine that has a water bypass hole?\u003c\/strong\u003e No. The 18-3506-1 circulating pump is built specifically for 4.3L MCM engines without a water bypass hole.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the impeller made of?\u003c\/strong\u003e The circulating pump uses a bi-directional brass impeller, which allows it to operate correctly regardless of pump rotation direction.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eAre gaskets included with this pump?\u003c\/strong\u003e Yes, mounting gaskets are included with the 18-3506-1 circulating pump so it is ready to install.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the circulating pump weigh?\u003c\/strong\u003e The Sierra 18-3506-1 weighs 10.69 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes this pump fit both stamped steel and composite timing covers?\u003c\/strong\u003e Yes, the 18-3506-1 pump is designed to work with both stamped steel and composite timing covers.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-3506-1 a genuine Sierra part?\u003c\/strong\u003e Yes, it is a Sierra manufactured circulating pump backed by Sierra's limited warranty.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow is the quality of this pump verified before shipping?\u003c\/strong\u003e Each 18-3506-1 pump is inspected for proper fit, form, and function, then finished with a vacuum test to confirm a proper seal.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material is the pump shaft and backing plate made from?\u003c\/strong\u003e The shaft and backing plate on this circulating pump are stainless steel for corrosion protection.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the impeller direction-specific?\u003c\/strong\u003e No, the brass impeller in the 18-3506-1 is bi-directional, so it functions properly in either rotation direction.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat warranty comes with the 18-3506-1 circulating pump?\u003c\/strong\u003e The pump is covered by Sierra's limited warranty.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988149743835,"sku":"SIE-18-3506-1","price":221.94,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/18-3506-1__71800.1737866349.500.750.jpg?v=1785188254","url":"https:\/\/www.goodvibesmarina.com\/products\/circulating-water-pump-for-mercruiser-4-3l-v6-replaces-46-879194401-sierra-18-3506-1","provider":"Good Vibes Marina","version":"1.0","type":"link"}