Sierra 18-0389 Heat Exchanger End Gasket, Replaces 27-75450, 224 CID, 2-3/4 Inch Diameter

The Sierra 18-0389 Heat Exchanger End Gasket seals the end cover of the heat exchanger on 224 CID marine engines, forming the barrier between the raw water and coolant sides of the cooling system. It is built as a direct cross-reference replacement for OEM number 27-75450, giving boat owners and marine technicians a reliable option for cooling system service and rebuilds without waiting on OEM parts. The gasket measures 2-3/4 inches in diameter, sized to match the heat exchanger end cover it is designed for.

This gasket is a wear item that should be replaced any time the heat exchanger end cap is removed for inspection, descaling, or cleaning, since a used gasket will not reliably reseal and can allow coolant or raw water leakage. Installing a fresh gasket at each service interval helps maintain proper sealing pressure across the heat exchanger end cover and supports consistent engine cooling performance. As part of the Mercruiser cooling system parts group, it is intended for use during routine heat exchanger maintenance and cooling system rebuilds.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-0389
• Product Type: Heat Exchanger End Gasket
• Diameter: 2-3/4 inches
• Engine Displacement: 224 CID
• OEM Cross Reference: 27-75450
• Shape: Round
• Color: Multicoloured
• UPC: 030999873705
• Package Quantity: 1
• Weight: 0.08 pounds

Fitment

Designed for 224 CID marine engines using a heat exchanger cooling system.

Replaces (OEM)

• 27-75450

Frequently Asked Questions

What does the Sierra 18-0389 Heat Exchanger End Gasket fit? The Sierra 18-0389 is designed for 224 CID marine engines that use a heat exchanger cooling system, sealing the heat exchanger end cover.

What OEM part number does the 18-0389 gasket replace? It replaces OEM number 27-75450, making it a direct cross-reference for that original part.

What is the diameter of this gasket? The Sierra 18-0389 Heat Exchanger End Gasket measures 2-3/4 inches in diameter.

How many gaskets come in one package? Each package of the 18-0389 contains a package quantity of 1 gasket.

How much does the 18-0389 gasket weigh? It weighs 0.08 pounds.

When should this heat exchanger end gasket be replaced? Replace the 18-0389 gasket any time the heat exchanger end cover is removed for cleaning, descaling, or inspection, since a reused gasket will not reseal reliably.

Is the Sierra 18-0389 an OEM part or an aftermarket replacement? The 18-0389 is a Sierra aftermarket gasket manufactured as a cross-reference replacement for OEM part 27-75450, not an OEM-branded part.

What happens if this gasket is not replaced during heat exchanger service? Reinstalling an old, compressed gasket on the heat exchanger end cover of a 224 CID engine can lead to coolant or raw water leaks at the end cover seam.

What shape and color is the 18-0389 gasket? The Sierra 18-0389 is a round gasket with a multicoloured appearance.

Is the Sierra 18-0389 gasket suitable for a cooling system rebuild? Yes, it is intended for use in heat exchanger maintenance and cooling system rebuilds on 224 CID marine engines.