Sierra 18-1957-2 Exhaust Manifold for Mercruiser Stern Drive Engines (Replaces 89011A8)

The Sierra 18-1957-2 is an exhaust manifold built for Mercruiser stern drive engines, designed to move spent exhaust gases away from the engine and into the exhaust elbow and riser system while keeping the engine bay running cool and dry. It is manufactured to meet or exceed original equipment quality, giving boat owners a direct, no-compromise replacement for a worn, cracked, or corroded factory manifold. The 18-1957-2 is finished in white and will fit either the port or starboard side of the engine, so it works whichever side needs replacing.

This manifold pairs with Sierra's related riser and spacer components, including the 18-1908K manifold spacer kit, which is specifically listed as compatible with the 18-1957-2 and includes spacers, a restrictor, gaskets, and mounting hardware for a complete riser installation. Buyers replacing a manifold on a Mercruiser stern drive engine can order the 18-1957-2 directly using its own part number or any of its Mercruiser OEM cross-reference numbers.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-1957-2
• Product Type: Exhaust Manifold
• UPC: 808282371357
• Weight: 47.55 pounds
• Dimensions: 20.25 x 9.75 x 7 inches
• Color: White
• Mounting Side: Fits either port or starboard
• Included Components: Manifold
• Compatible Accessory: 18-1908K Manifold Spacer Kit

Fitment

• Mercruiser stern drive engines
• Fits either port or starboard side

Replaces (OEM)

• Mercruiser 89011A8
• Mercruiser 807078A6
• Mercruiser 807078T10
• Mercruiser 807078T09
• Mercruiser 807078A4
• Mercruiser 807078A2

Frequently Asked Questions

What does the Sierra 18-1957-2 manifold fit? The 18-1957-2 is built for Mercruiser stern drive engines and can be installed on either the port or starboard side.

Is this manifold for port or starboard? The Sierra 18-1957-2 fits either port or starboard, so the same part number works on both sides of the engine.

What Mercruiser OEM numbers does the 18-1957-2 replace? It replaces Mercruiser 89011A8, 807078A6, 807078T10, 807078T09, 807078A4, and 807078A2.

How much does the Sierra 18-1957-2 exhaust manifold weigh? It weighs 47.55 pounds.

What are the dimensions of the 18-1957-2 manifold? The packaged dimensions of the Sierra 18-1957-2 manifold are 20.25 x 9.75 x 7 inches.

What color is the 18-1957-2 manifold? The Sierra 18-1957-2 exhaust manifold is finished in white.

Is the Sierra 18-1957-2 an OEM part or an aftermarket replacement? It is a Sierra-manufactured aftermarket manifold made to meet or exceed original equipment quality, sold under Sierra's own part number 18-1957-2.

Does the 18-1957-2 come with mounting hardware or gaskets? The manifold itself includes only the manifold; mounting hardware and gaskets for the riser connection are supplied separately in the 18-1908K manifold spacer kit.

What is included in the box with this manifold? The Sierra 18-1957-2 ships as a single manifold unit.

Can the 18-1908K spacer kit be used with the 18-1957-2 manifold? Yes, the 18-1908K manifold spacer kit is specifically listed as compatible with the 18-1957-2 and includes spacers, a restrictor, gaskets, and mounting hardware.

How is the Sierra 18-1957-2 different from a used or reconditioned manifold? The 18-1957-2 is a new manifold manufactured to meet or exceed original equipment quality, rather than a rebuilt or salvaged unit.