Sierra Manifold Gasket 18-0183-1, Replaces 27-73866, for Exhaust Manifolds 18-1958-1 & 18-1962-1

The Sierra 18-0183-1 is a manifold gasket engineered to seal the connection between the exhaust manifold and the engine block on applicable inboard and sterndrive setups. It is designed for use with Sierra exhaust manifolds 18-1958-1 and 18-1962-1, and it is also included as a component in the Sierra 18-8509 mounting kit for buyers who need the full mounting hardware set rather than the gasket alone. A proper manifold gasket is a critical wear item: it maintains the seal against combustion gases, exhaust backpressure, and cooling water routed through the manifold passages, and a worn or failed gasket is a common cause of exhaust leaks, water intrusion, or gasket-related corrosion around the manifold mounting surface. Replacing this gasket whenever the manifold is removed, serviced, or reinstalled helps ensure a proper seal and prevents having to redo the job due to a compromised old gasket. This part cross-references directly to OEM number 27-73866, so it is a straightforward drop-in replacement for that OEM gasket. At 0.2 pounds, it ships and installs easily alongside routine manifold maintenance or a full manifold replacement.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-0183-1
• Product Type: Manifold Gasket
• Weight: 0.2 pounds
• Used With: Manifolds 18-1958-1, 18-1962-1
• Also Included In: 18-8509 mounting kit
• OEM Cross-Reference: 27-73866

Fitment

• Use with exhaust manifold 18-1958-1
• Use with exhaust manifold 18-1962-1

Replaces (OEM)

• 27-73866

Frequently Asked Questions

What does the Sierra 18-0183-1 gasket fit? The 18-0183-1 manifold gasket is designed for use with exhaust manifolds 18-1958-1 and 18-1962-1.

Is 18-0183-1 the same as OEM part 27-73866? Yes, the Sierra 18-0183-1 gasket cross-references directly to OEM number 27-73866, making it a direct replacement for that part.

How much does this gasket weigh? The 18-0183-1 manifold gasket weighs 0.2 pounds.

Does this gasket come with the mounting kit? It is included as a component of the 18-8509 mounting kit, and it is also sold separately as the standalone 18-0183-1 gasket for buyers who only need the gasket.

Will I need more than one gasket for a manifold job? That depends on your manifold configuration; check whether your installation uses one or two manifolds, since each 18-1958-1 or 18-1962-1 manifold requires its own 18-0183-1 gasket.

Can I reuse my old manifold gasket instead of replacing it? Manifold gaskets like the 18-0183-1 are designed as one-time-use sealing components, and reusing a compressed or damaged gasket increases the risk of exhaust or water leaks at the manifold joint.

What is included in the 18-8509 mounting kit? The 18-8509 mounting kit includes the 18-0183-1 manifold gasket along with mounting bolts for installing the manifold.

Is the 18-0183-1 gasket for the manifold-to-block connection? Yes, this gasket seals the exhaust manifold at its mounting point for manifolds 18-1958-1 and 18-1962-1.

What OEM number should I search for if I only have the old part in hand? Look for OEM number 27-73866; the Sierra 18-0183-1 gasket is the direct replacement for that number.

Do I need special tools to install this gasket? Installation follows standard manifold gasket procedure: remove the old gasket, clean the mating surfaces, and torque the manifold bolts to the engine manufacturer's specification with the new 18-0183-1 gasket in place.