Sierra Exhaust Elbow Gasket 18-0881-1 for MerCruiser 3.7L 170/180 HP Aluminum Exhaust Manifolds

The Sierra 18-0881-1 is an exhaust elbow gasket engineered as a direct-fit seal for MerCruiser 3.7L 224 cid 4-cylinder sterndrive engines equipped with aluminum exhaust manifolds. It seals the mating surface between the exhaust manifold and exhaust elbow, containing hot exhaust gas and cooling water so the joint stays leak-free under the heat cycling and vibration typical of marine engine operation. Because this gasket is specified for the aluminum manifold configuration rather than the cast iron version, it is engineered to match the mounting geometry and surface finish of aluminum manifold assemblies specifically -- installing the wrong gasket variant on the wrong manifold material can lead to a poor seal and coolant or exhaust leakage.

This gasket applies to MerCruiser 3.7L engines rated at 170 HP (1985-1986 model years, serial numbers 6916779 through B434940) and 180 HP (1987 model year, serial numbers B436391 through B775248), both using the 224 cid 4-cylinder block with aluminum exhaust manifolds. At 0.14 pounds, it is a lightweight, precision-cut flat gasket intended as a one-for-one replacement during exhaust manifold or exhaust elbow service, gasket refresh after removal, or routine maintenance where the manifold-to-elbow joint is disturbed.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-0881-1
• Product Name: Exhaust Elbow Gasket
• Weight: 0.14 pounds
• UPC: 808282365820
• Engine Application: MerCruiser 3.7L, 224 cid, 4-cylinder
• Exhaust Manifold Type: Aluminum exhaust manifold configuration
• Horsepower Ratings: 170 HP and 180 HP
• Model Years: 1985-1986 (170 HP), 1987 (180 HP)
• Serial Number Range: 6916779 - B434940 (170 HP); B436391 - B775248 (180 HP)

Fitment

• MerCruiser 3.7L, 224 cid, 4-cylinder, 170 HP, 1985-1986, serial numbers 6916779 - B434940, aluminum exhaust manifolds
• MerCruiser 3.7L, 224 cid, 4-cylinder, 180 HP, 1987, serial numbers B436391 - B775248, aluminum exhaust manifolds

Frequently Asked Questions

What engines does the Sierra 18-0881-1 exhaust elbow gasket fit? It fits MerCruiser 3.7L, 224 cid, 4-cylinder engines rated at 170 HP (1985-1986, serial numbers 6916779 - B434940) and 180 HP (1987, serial numbers B436391 - B775248), specifically the versions with aluminum exhaust manifolds.

Does this gasket work with cast iron exhaust manifolds? No, the 18-0881-1 gasket is specified for the aluminum exhaust manifold configuration on the MerCruiser 3.7L 224 cid engine; engines with cast iron exhaust manifolds require a different gasket part number.

How much does the 18-0881-1 exhaust elbow gasket weigh? 0.14 pounds is the weight of the Sierra 18-0881-1 exhaust elbow gasket.

Where on the engine does this gasket install? The 18-0881-1 seals the joint between the exhaust manifold and the exhaust elbow on applicable MerCruiser 3.7L aluminum-manifold engines, sealing both exhaust gas and cooling water at that connection.

Can I use this gasket for a routine exhaust elbow gasket replacement? Yes, the 18-0881-1 is intended as a direct replacement gasket for service work whenever the exhaust manifold-to-elbow joint on a covered MerCruiser 3.7L aluminum-manifold engine is disassembled.

Is the Sierra 18-0881-1 a genuine Sierra part or aftermarket equivalent? 18-0881-1 is the Sierra manufacturer part number for this exhaust elbow gasket, sold as Sierra's own catalog item rather than a third-party equivalent.

What model years does the 170 HP application cover? The 170 HP MerCruiser 3.7L application for the 18-0881-1 gasket covers 1985-1986 model years, engine serial numbers 6916779 through B434940.

What model years does the 180 HP application cover? 1987 is the model year for the 180 HP MerCruiser 3.7L application of the 18-0881-1 gasket, spanning serial numbers B436391 through B775248.

What is included when I order this part? Ordering the Sierra 18-0881-1 includes one exhaust elbow gasket sized for the MerCruiser 3.7L aluminum exhaust manifold applications listed for this part.

How do I know if my engine has aluminum or cast iron exhaust manifolds? Since the 18-0881-1 gasket is built specifically for the aluminum exhaust manifold version of the MerCruiser 3.7L 224 cid engine, confirming manifold material before ordering ensures the correct gasket is installed, as the cast iron version uses a different Sierra part number.