Sierra Exhaust Elbow Gasket 18-2849 for Mercruiser Exhaust Manifolds - Available Single or Pack of 2

The Sierra 18-2849 Exhaust Elbow Gasket is an open-style gasket that seals the connection between the exhaust manifold and the exhaust manifold elbow on applicable Mercruiser stern drive installations. It is designed to fit the 18-1957-2 exhaust manifold (used on GM Big Block V8 454 cu. In. Applications, Models 330, 340 & 7.4L) and mates with the 18-1970-2 (3 inch hose), 18-1976-2 (4 inch hose, 7 degree down angle), and 18-1974-1 (3 inch hose, 15 degree down angle) manifold elbows. The gasket is constructed from a stainless steel infused graphite material engineered for superior compressibility, giving it a reliable seal against exhaust gas and cooling water leakage at the manifold-to-elbow joint. Its round, open-flow design matches the factory port profile so exhaust and water flow are not restricted.

This gasket is a routine maintenance and repair item, typically replaced any time the exhaust elbow is removed for service, inspection, or corrosion, or as part of a preventive maintenance schedule to avoid gasket failure and coolant intrusion. It is available as a single gasket or in a package of 2, so owners replacing elbows on both sides of the engine, or keeping a spare on hand, can order the quantity that matches the job.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2849
• Product Type: Exhaust Elbow Gasket
• Design: Open
• OEM Cross Reference: 27-818832
• Fits Manifold: 18-1957-2 (GM Big Block V8 454 cu. In., Models 330, 340 & 7.4L)
• Fits Elbows: 18-1970-2 (3 inch hose), 18-1976-2 (4 inch hose, 7 degree down angle), 18-1974-1 (3 inch hose, 15 degree down angle)
• Material: Stainless steel infused graphite
• Color: Black
• Shape: Round
• Packaging Options: Single or pack of 2

Sizes & Options

This gasket is sold two ways: as a single gasket, or as a package of 2. Choose the single option if you are replacing one elbow gasket, or the pack of 2 if you are servicing elbows on both sides of the engine or want a spare on hand. Both options are the identical open-style gasket fitting the 18-1957-2 manifold and its matching 18-1970-2, 18-1976-2, and 18-1974-1 elbows; only the quantity in the package differs.

Frequently Asked Questions

What does the Sierra 18-2849 exhaust elbow gasket fit? The 18-2849 gasket fits the 18-1957-2 exhaust manifold and seals it to the 18-1970-2, 18-1976-2, or 18-1974-1 manifold elbows.

Is this gasket sold as a single piece or in a pack? The Sierra 18-2849 gasket is available either as a single gasket or as a package of 2, so you can order the exact quantity needed for a one-side or two-side elbow replacement.

What is the OEM cross reference number for this gasket? The 18-2849 gasket cross references to Mercruiser/Mercury number 27-818832.

What material is the exhaust elbow gasket made from? It is made from a stainless steel infused graphite material, chosen for its compressibility and ability to hold a reliable seal at the exhaust elbow joint.

Is this an open or blocked style gasket? This is the open-style elbow gasket (18-2849), which matches manifolds using the open exhaust port configuration, as opposed to a blocked-style gasket.

Which manifold elbows use this gasket? The 18-2849 gasket is used with the 18-1970-2 elbow (3 inch hose), the 18-1976-2 elbow (4 inch hose, 7 degree down angle), and the 18-1974-1 elbow (3 inch hose, 15 degree down angle).

How do I know if I need the single gasket or the pack of 2? If you are only replacing one exhaust elbow, order the single 18-2849 gasket; if you are servicing elbows on both sides of the engine or want a spare in reserve, order the pack of 2.

What color is the gasket and what shape is it? The Sierra exhaust elbow gasket is black and round in shape, matching the factory open exhaust port profile.

Does this gasket work with the 18-1957-2 manifold? Yes, the 18-2849 gasket is designed to fit the 18-1957-2 exhaust manifold, which is used on GM Big Block V8 454 cu. In. Applications, Models 330, 340 and 7.4L.

Do I need any other gaskets or hardware with this part? The 18-2849 elbow gasket seals the manifold-to-elbow joint only; the corresponding manifold gasket and mounting hardware for the 18-1957-2 manifold are separate parts.

Is the 18-2849 gasket genuine Sierra or aftermarket? It is a Sierra-branded exhaust elbow gasket, sold under Sierra part number 18-2849, and is backed by Sierra.