Sierra 18-0721 Dry Joint Open Riser Gasket Rep: Mercruiser 27-865447A02 NOS 0810

Sierra Replacement Dry Joint Open Exhaust Riser Gasket — Part Number 18-0721
Brand: Sierra | Condition: New Old Stock (NOS)

You are purchasing a Sierra aftermarket replacement Dry Joint Open Exhaust Riser Gasket, part number 18-0721, for MerCruiser GM V-6 and V-8 sterndrive engines (2002 and newer) equipped with the dry joint exhaust manifold and riser system. This open-style riser gasket (two water passages / standard cooling full-flow configuration) seals the interface between the exhaust riser and the exhaust manifold — preventing exhaust gas leakage and maintaining proper separation of exhaust gases and cooling water at this critical junction. A failed or compromised riser gasket allows water to enter the exhaust manifold or exhaust gases to leak, potentially leading to engine overheating or serious damage. Sierra parts are engineered to meet or exceed the original equipment part they replace. This is a new, never-installed part.

Condition Details: This is a New Old Stock (NOS) part. The gasket itself is in new, uninstalled condition. As is common with NOS inventory, the original packaging may show signs of age, including shelf wear, dust, or minor cosmetic blemishes on the bag or box. The part is new and fully functional.

Part Number / Supersede Information:

• Sierra Part Number: 18-0721
• Replaces MerCruiser OEM Part Numbers: 27-864547A02, 27-864547A1
• For use with: Sierra Exhaust Manifold 18-1843 and Sierra Exhaust Elbow/Riser 18-1845
• Related Sierra gaskets: Closed style 18-0720, Constricted style 18-0722
• We recommend verifying fitment through your local dealer or the official MerCruiser parts catalog prior to ordering.

Compatible Equipment: MerCruiser GM V-6 and V-8 sterndrive engines with dry joint exhaust manifold system (2002 and newer) including 4.3L, 5.0L, 5.7L, and 6.2L applications — including 5.0L MPI Alpha/Bravo (0M300000 and up), 5.7L CARB Alpha/Bravo (0M600000 and up), 350 MAG MPI Alpha/Bravo (0L010019 and up), and 350 MAG MPI Horizon Alpha/Bravo (0M300000 and up) — verify specific engine serial number and manifold type fitment prior to ordering.

Why Choose Quality Replacement Parts? Sierra parts are manufactured to meet or exceed OEM specifications, ensuring reliable performance and a proper fit — delivering the quality and dependability you need at a competitive price.

Returns: We proudly offer hassle-free returns. If you are not completely satisfied with your purchase for any reason, simply open a return request through eBay within 30 days of purchase and we will take care of you promptly.

Thank you for choosing QBS Parts Inc! We truly appreciate your business. If you have any issues whatsoever with your order, please give us the opportunity to resolve it before leaving feedback — we are committed to making every transaction a great experience. Please verify fitment using your equipment's model and serial number before purchasing. Feel free to message us with any questions — we're here to help!

QBS Parts, Inc. — Gardena, CA