Sierra 18-2823-9 Lower Water Pump Gasket, Replaces 27-32769/27-19553, Fits 40-50-70 HP Mercury Marine/Mercruiser, Pack of 2

The Sierra 18-2823-9 is a lower water pump gasket sold in a package of two, designed to seal the lower section of the water pump housing on 40-50-70 HP Mercury Marine and Mercruiser stern drive engines. This gasket sits between the water pump base and the lower housing, forming the seal that keeps raw cooling water flowing through the correct passages and prevents leaks at the pump base during operation. Because water pump gaskets harden, compress, and lose their seal over time, replacing this gasket is a standard step whenever the water pump is serviced, rebuilt, or has its impeller replaced.

Each package includes two gaskets, so a single purchase covers a complete water pump service without needing a second order. The 18-2823-9 is built to the same fit and seal performance as the original equipment gasket it replaces, cross-referencing directly to OEM part numbers 27-32769 and 27-19553. Installing the correct lower water pump gasket helps maintain proper cooling system pressure and prevents water intrusion or leakage at the pump housing, which can otherwise lead to overheating or reduced water pump performance.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2823-9
• Product Type: Lower Water Pump Gasket
• Pack Quantity: 2 gaskets per package
• HP Rating: 40-50-70 HP
• Application: Mercury Marine and Mercruiser stern drive engines
• OEM Cross Reference: 27-32769, 27-19553
• Weight: 0.03 pounds
• UPC: 808282163303

Fitment

• 40-50-70 HP Mercury Marine and Mercruiser stern drive engines

Replaces (OEM)

• 27-32769
• 27-19553

Frequently Asked Questions

What does the Sierra 18-2823-9 gasket fit? The 18-2823-9 lower water pump gasket fits 40-50-70 HP Mercury Marine and Mercruiser stern drive engines.

How many gaskets come in a package of 18-2823-9? Each package of the 18-2823-9 contains 2 lower water pump gaskets, enough for one complete water pump service.

Is the 18-2823-9 gasket a direct OEM replacement? Yes, the 18-2823-9 is built to seal and fit the same as the original equipment gasket it replaces, matching OEM part numbers 27-32769 and 27-19553.

What OEM part numbers does the 18-2823-9 replace? The Sierra 18-2823-9 replaces OEM numbers 27-32769 and 27-19553.

Where on the water pump does this gasket install? This gasket seals the lower section of the water pump housing, sitting between the pump base and the lower housing on the engine's water pump assembly.

When should I replace the lower water pump gasket? Replace the 18-2823-9 lower water pump gasket any time the water pump is serviced, rebuilt, or the impeller is replaced, since the old gasket can harden and lose its seal over time.

What happens if I reuse the old gasket instead of installing a new 18-2823-9? A worn or hardened lower water pump gasket can leak at the pump base, allowing water intrusion or loss of cooling water pressure, so Sierra recommends installing a fresh 18-2823-9 during pump service rather than reusing the old gasket.

How much does the 18-2823-9 gasket weigh? The Sierra 18-2823-9 lower water pump gasket package weighs 0.03 pounds.

Does the 18-2823-9 come with the impeller? No, the 18-2823-9 is the lower water pump gasket only, sold as a pack of 2; the impeller and impeller gasket are separate parts.

Is the 18-2823-9 gasket engine-specific by horsepower? Yes, the 18-2823-9 is designed for the 40-50-70 HP range of Mercury Marine and Mercruiser stern drive engines.