Sierra V-Belt 18-15370 - 37 Inch Belt for MerCruiser 120 HP 2.5L 153 CID Stern Drive

The Sierra 18-15370 is a premium aftermarket V-belt engineered to OEM quality standards for correct fit, form, and function on applicable MerCruiser stern drive engines. This belt measures 37 inches in effective length with a 29/64 inch (11.5mm) top width, sized to drive accessories such as the sea water pump pulley on covered applications.

Construction combines a synthetic fiber fabric cover, special polyester cord, and a polychloroprene rubber body. The high-strength synthetic cords resist shock loading and hold low-stretch properties for uniform performance over the belt's service life, while the rubber compound section provides smooth, even transfer of load forces to the cords. The belt also offers oil resistance and temperature stability, both standard features across the Sierra belt line. It is finished in white and weighs 0.22 pounds.

The 18-15370 is intended for MerCruiser 120 HP 2.5L 153 CID, 4-cylinder engines built 1982-89 (engine serial number range 6229718 - C853255), for use with a cast aluminum sea water pump pulley. It cross-references directly to commonly searched Mercury Marine and Mallory belt numbers, making it a straightforward replacement when the original belt has cracked, glazed, or stretched.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-15370
• Product Type: V-Belt
• Effective Length: 37 inches
• Top Width: 29/64 inch (11.5 mm)
• Material: Rubber (polychloroprene rubber body with synthetic fiber fabric cover and polyester cord)
• Color: White
• Weight: 0.22 pounds
• Engine Serial Number Range: 6229718 - C853255
• Compatible Pulley: Cast aluminum sea water pump pulley
• OEM Cross Reference: 57-65607T, 9-55005, 57-65607, 57-65607Q

Fitment

• MerCruiser 120 HP, 2.5L, 153 CID, 4 cylinder, 1982-89 (engine serial number range 6229718 - C853255)

Replaces (OEM)

• 57-65607T
• 9-55005
• 57-65607
• 57-65607Q

Frequently Asked Questions

What is the effective length and width of the Sierra 18-15370 V-belt? The Sierra 18-15370 has a 37 inch effective length and a 29/64 inch (11.5mm) top width.

Which engines does the Sierra 18-15370 V-belt fit? This belt fits MerCruiser 120 HP 2.5L 153 CID, 4-cylinder engines built 1982-89, within engine serial number range 6229718 - C853255.

Is the Sierra 18-15370 the same as the Mercury Marine 57-65607 belt? Yes, the Sierra 18-15370 cross-references to Mercury Marine 57-65607T, 57-65607, and 57-65607Q, as well as Mallory 9-55005, so it functions as a direct equivalent.

What material is the 18-15370 V-belt made of? It is built with a polychloroprene rubber body, a synthetic fiber fabric cover, and special polyester cord for durability and oil resistance.

What color is the Sierra 18-15370 V-belt? The 18-15370 belt is white.

How much does the Sierra 18-15370 V-belt weigh? It weighs 0.22 pounds.

Does the 18-15370 belt require a specific pulley? The 18-15370 is designed for use with a cast aluminum sea water pump pulley on its covered MerCruiser application.

Is the 18-15370 belt resistant to heat and oil exposure? Yes, oil resistance and temperature stability are standard features of this Sierra belt, helping it hold up in the engine bay environment.

What is included when ordering the Sierra 18-15370? Ordering the 18-15370 gets you one Sierra V-belt sized for the specified MerCruiser 120 HP 2.5L application.

How does the 18-15370 differ from the Sierra 18-15400 belt? The 18-15400 and 18-15370 are separate Sierra V-belt part numbers listed for overlapping MerCruiser 120 HP 2.5L applications; confirm engine serial number range 6229718 - C853255 and pulley type before ordering to get the correct one.

Why do the belt's low-stretch properties matter? The 18-15370's high-strength synthetic cords keep stretch low, which assures uniform performance and reduces slippage over the belt's service life.