27-99777-2 Rear Riser Open Exhaust Elbow Gasket Set for MerCruiser

SERDAMARINE / MARINE EXHAUST PARTS

Rear Riser Open Exhaust Elbow Gasket Set (2 Pieces)

This two-piece rear-riser open exhaust elbow gasket set seals the joint between the exhaust manifold and the exhaust elbow or adaptor on listed MerCruiser 4-cylinder, 6-cylinder, and V8 engines, referencing OEM number 27-99777-2. It is configured specifically for open-passage rear-riser joints and is distinct from the closed-cooling blocking-gasket configuration referenced under 27-92720 or GLM 32630.

Configuration & Specifications

Engine Applications

This gasket set fits listed MerCruiser applications equipped with a rear-riser exhaust manifold-to-elbow or adaptor joint using the open-gasket pattern. Verify that your assembly requires the open passage rather than a blocking gasket; on 2.5L and 3.0L engines from 1983–1994, check the installed exhaust-joint configuration directly before ordering.

• MerCruiser 4-Cylinder and 6-Cylinder (except 120 hp) — Years: 1968–1982. Rear riser exhaust manifold to elbow or adaptor joint with open gasket pattern. Fits when specified
• MerCruiser All V8 — Years: 1978–1982. Rear riser exhaust manifold to elbow or adaptor joint with open gasket pattern. Fits when specified
• MerCruiser Model 140 — Inline 4, GM 181 CID, 4-Cylinder. Years: 1968–1982. Rear riser exhaust manifold to elbow or adaptor joint with open gasket pattern. Fits when specified
• MerCruiser Model 120 / 140 — Inline 4, 153 / 181 CID, 4-Cylinder. Years: 1982–1995. Rear riser exhaust manifold to elbow or adaptor joint with open gasket pattern. Fits when specified
• MerCruiser Model 3.0L / 3.0LX — Inline 4, GM 181 CID, 4-Cylinder. Years: 1990 and up. Rear riser exhaust manifold to elbow or adaptor joint with open gasket pattern. Fits when specified
• MerCruiser 2.5L — Years: 1983–1994. Rear riser exhaust manifold to elbow or adaptor joint; confirm installed open-gasket exhaust-joint configuration. Fits when specified
• MerCruiser 3.0L — Years: 1983–1994. Rear riser exhaust manifold to elbow or adaptor joint; confirm installed open-gasket exhaust-joint configuration. Fits when specified

Additional model-specific applications

• MerCruiser 4-cylinder applications, 1968–1982; except 120 HP; rear-riser open gasket at the exhaust manifold-to-elbow or adaptor joint.
• MerCruiser 6-cylinder applications, 1968–1982; except 120 HP; rear-riser open gasket at the exhaust manifold-to-elbow or adaptor joint.
• MerCruiser all V8 applications, 1978–1982; rear-riser open gasket; specific V8 models are not individually identified.
• MerCruiser MODEL 3.0LX, from 1990 onward; inline 4, GM 181 CID; confirm rear-riser open-gasket exhaust configuration.
• MerCruiser 2.5L application, 1983–1994; exhaust manifold gasket set application; confirm rear-riser open-gasket joint. Cylinder configuration and model code not specified.
• MerCruiser 3.0L application, 1983–1994; exhaust manifold gasket set application; confirm rear-riser open-gasket joint. Cylinder configuration not specified in this sales-note statement.
• MerCruiser 4-cylinder applications, 120 HP, 1968; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 4-cylinder applications, 120 HP, 1969; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 4-cylinder applications, 120 HP, 1970; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 4-cylinder applications, 120 HP, 1971; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 4-cylinder applications, 120 HP, 1972; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 4-cylinder applications, 120 HP, 1973; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 4-cylinder applications, 120 HP, 1974; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 4-cylinder applications, 120 HP, 1975; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 4-cylinder applications, 120 HP, 1976; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 4-cylinder applications, 120 HP, 1977; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 4-cylinder applications, 120 HP, 1978; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 4-cylinder applications, 120 HP, 1979; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 4-cylinder applications, 120 HP, 1980; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 4-cylinder applications, 120 HP, 1981; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 4-cylinder applications, 120 HP, 1982; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 6-cylinder applications, 120 HP, 1968; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 6-cylinder applications, 120 HP, 1969; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 6-cylinder applications, 120 HP, 1970; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 6-cylinder applications, 120 HP, 1971; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 6-cylinder applications, 120 HP, 1972; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 6-cylinder applications, 1973; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 6-cylinder applications, 1974; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 6-cylinder applications, 1975; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 6-cylinder applications, 1976; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 6-cylinder applications, 1977; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 6-cylinder applications, 1978; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 6-cylinder applications, 1979; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 6-cylinder applications, 1980; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 6-cylinder applications, 1981; Excluded: 1968–1982 4/6-cylinder applications.
• MerCruiser 6-cylinder applications, 1982; Excluded: 1968–1982 4/6-cylinder applications.

Reference Numbers

The numbers below are provided for part identification and cross-reference only; they do not alone guarantee interchangeability across different joint configurations or indicate manufacturer identity.

Supplied Parts

• 2 × Rear-riser open exhaust elbow gaskets

Service & Installation Notes

General service guidance only. Use the service manual for your exact engine and exhaust configuration.

1. Ensure the engine is shut off, completely cool, and secured against accidental starting before servicing any exhaust components.
2. Support the exhaust elbow or adaptor during disassembly and carefully clean both mating surfaces on the manifold and elbow/adaptor without gouging the sealing planes.
3. Compare the new open gasket directly against the removed gasket and the casting passages to verify that an open-passage pattern is required rather than a blocking gasket.
4. Position the gasket and tighten the mounting fasteners according to the sequence and specifications in your engine service manual. If any abnormal leakage or temperature issue occurs during operation, shut down the engine immediately and inspect the joint.

The Serdamarine Approach

Exhaust parts need a configuration match. Serdamarine focuses on marine exhaust manifolds and their related service parts. Application details, connection requirements and public reference numbers are presented together to support part selection.

Questions Before Replacement