Sierra 18-2915-9 Water Pump Gasket, Replaces 27-856091, Mercruiser Stern Drive and Mercury Marine, Pack of 2

The Sierra 18-2915-9 Water Pump Gasket is a direct-fit replacement gasket engineered for Mercruiser stern drive and Mercury marine water pump applications. Each package contains two gaskets, giving boat owners enough material on hand to complete a full water pump service or keep a spare ready for the next maintenance interval. The gasket seals the water pump housing to prevent coolant and raw water leaks, helping the cooling system maintain proper pressure and flow to protect the engine from overheating.

Sierra manufactures this gasket to meet or exceed the specifications of the original equipment part it replaces, making it a reliable choice for routine water pump rebuilds and repairs. It is designed as a direct cross-reference to several Mercruiser and Mercury Marine OEM part numbers, so it fits into the same service procedures without modification. Because it ships as a pack of two, it is priced and packaged for a complete water pump gasket replacement job.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2915-9
• Product Type: Water Pump Gasket
• Quantity: Pack of 2
• Weight: 0.03 pounds
• Category: Mercury Outboard Thermostats & Gaskets

Fitment

• Mercruiser stern drive applications
• Mercury marine applications

Replaces (OEM)

• 27-856091
• 27-858524
• 27-85609
• 27-32434
• 27-30604

Frequently Asked Questions

What does the Sierra 18-2915-9 Water Pump Gasket fit? The 18-2915-9 gasket is designed for use in Mercruiser stern drive and Mercury marine water pump applications.

How many gaskets come in a package? Each package of the 18-2915-9 includes two water pump gaskets, enough for a complete water pump gasket replacement.

Which OEM part numbers does the 18-2915-9 replace? It replaces OEM numbers 27-856091, 27-858524, 27-85609, 27-32434, and 27-30604.

Is the Sierra 18-2915-9 an OEM part or an aftermarket replacement? It is an aftermarket Sierra replacement gasket that Sierra manufactures to meet or exceed the specifications of the original equipment part it replaces.

How much does the 18-2915-9 gasket weigh? The 18-2915-9 Water Pump Gasket, per package of two, weighs 0.03 pounds.

Can this gasket be used for a Mercury outboard water pump? The 18-2915-9 falls under Sierra's Mercury Outboard Thermostats & Gaskets category and is designed for Mercruiser stern drive and Mercury marine water pump applications.

Does the 18-2915-9 replace 27-32434? Yes, 27-32434 is one of the OEM part numbers that the Sierra 18-2915-9 gasket replaces.

Is the 18-2915-9 gasket sold individually or as a pair? It is sold priced per package of two, not individually.

What is the correct part number to order for this gasket? The correct Sierra part number to order is 18-2915-9, the Water Pump Gasket packaged in a set of two.

When should the 18-2915-9 water pump gasket be replaced? This gasket should be replaced any time the water pump housing is removed for service, since reusing a worn gasket can lead to coolant or raw water leaks at the pump housing.