Sierra 18-4367 Exhaust Manifold Gasket Set, Replaces 27-99777A1, for GM 153 & 181 CID I/O Engines

The Sierra 18-4367 Exhaust Manifold Gasket Set is a replacement gasket kit for Mercruiser I/O engines equipped with siamese port cylinder heads. It is engineered to seal the exhaust manifold to the cylinder head, preventing exhaust and water leaks at the joint that can lead to overheating, corrosion, or engine damage if left unaddressed. This gasket set is built to meet or exceed the specifications of the original equipment part it replaces, standing up to the heat cycling, saltwater exposure, and vibration typical of the marine exhaust environment.

This set is designed specifically for GM 153 and 181 cubic inch displacement (2.5L and 3.0L) engines rated at 120 and 140 horsepower, with serial numbers 6229718 and up, on applications using siamese port cylinder heads. Installing the correct gasket set for this cylinder head configuration and serial number range is important, since earlier serial numbers or non-siamese port heads use a different gasket design. The Sierra 18-4367 directly replaces OEM part number 27-99777A1, so it installs as a drop-in replacement during exhaust manifold service or when addressing a leaking manifold gasket.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-4367
• Color: White
• Weight: 0.27 pounds
• UPC: 030999563309
• Engine Type: I/O (Mercruiser)
• Cylinder Head Type: Siamese Port
• Fitment: GM 153 & 181 (2.5L & 3.0L) CID engines, 120 & 140 HP, S/N 6229718 & Up

Fitment

• GM 153 & 181 (2.5L & 3.0L) CID engines
• 120 & 140 HP
• S/N 6229718 & Up
• With siamese port cylinder heads

Replaces (OEM)

• 27-99777A1

Frequently Asked Questions

What engines does the Sierra 18-4367 exhaust manifold gasket set fit? This gasket set fits GM 153 and 181 cubic inch displacement (2.5L and 3.0L) engines rated at 120 and 140 horsepower, specifically units with serial number 6229718 and up that use siamese port cylinder heads.

What OEM part number does the 18-4367 replace? It replaces OEM part number 27-99777A1, so it can be installed as a direct substitute during exhaust manifold gasket service.

Does this gasket set work with any cylinder head design? No, the 18-4367 is designed specifically for engines with siamese port cylinder heads; it is not intended for other cylinder head configurations.

Is a serial number range relevant when ordering this gasket set? Yes, the Sierra 18-4367 is intended for engines with serial number 6229718 and up; engines outside that range may require a different gasket set.

How much does the 18-4367 gasket set weigh? The Sierra 18-4367 Exhaust Manifold Gasket Set weighs 0.27 pounds.

What color is the Sierra 18-4367 gasket set? The gasket set is white.

Is the Sierra 18-4367 an OEM part or an aftermarket replacement? It is an aftermarket replacement manufactured by Sierra, engineered to meet or exceed the specifications of the original OEM part 27-99777A1 it replaces.

What horsepower ratings apply to engines using this gasket set? The 18-4367 is designed for engines rated at 120 and 140 horsepower within the GM 153 and 181 CID engine family.

Does the Sierra 18-4367 come with a warranty? Yes, the Sierra 18-4367 Exhaust Manifold Gasket Set is covered under Sierra's standard customer satisfaction warranty.

What is included in the Sierra 18-4367 kit? The kit includes the Sierra 18-4367 Exhaust Manifold Gasket Set components needed to seal the exhaust manifold to the cylinder head on applicable GM 153 & 181 CID engines.