Sierra Serpentine Belt 18-15121 for MerCruiser MX 6.2L MPI MIE, Horizon, Ski Engines

The Sierra 18-15121 serpentine belt is a direct-fit drive belt engineered for MerCruiser MX 6.2L MPI engines, including MIE, Horizon MIE, and Ski configurations within the applicable serial number ranges. It is built to OEM quality standards for correct fit, form, and function, so it drives the alternator, water pump, and other belt-driven accessories exactly as the original equipment belt did.

Construction uses high quality polychloroprene rubber combined with polyester fiber tensile members, giving the belt oil resistance and temperature stability for continuous duty in a marine engine compartment. The serpentine mount design routes a single belt around multiple pulleys, and the belt is finished in white.

This belt is intended for MerCruiser MX 6.2L MPI Horizon MIE and MX 6.2L MPI MIE engines with serial number OM310100 and up on engines with standard cooling, and for MerCruiser MX 6.2L MPI Ski engines with serial number OM317000 and up. Confirm your engine's serial number and cooling configuration before ordering, since MerCruiser used different belt part numbers across serial breaks and cooling types.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-15121
• Material: Polyester, Rubber
• Belt Style: Serpentine Mount
• Color: White
• Weight: 0.52 pounds
• UPC: 808282200442
• Country of Origin: United States
• OEM Cross Reference: 57-865615005
• Fitment: MerCruiser MX 6.2L MPI (MIE, Horizon MIE, Ski)

Fitment

• MerCruiser MX 6.2L MPI Horizon MIE, 2001-05, serial OM310100 and up, engines with standard cooling
• MerCruiser MX 6.2L MPI MIE, 2001-05, serial OM310100 and up, engines with standard cooling
• MerCruiser MX 6.2L MPI Ski, 2002-05, serial OM317000 and up

Replaces (OEM)

• 57-865615005

Frequently Asked Questions

What engines does the Sierra 18-15121 serpentine belt fit? This belt fits MerCruiser MX 6.2L MPI Horizon MIE and MX 6.2L MPI MIE engines from 2001-05 with serial number OM310100 and up on engines with standard cooling, and MerCruiser MX 6.2L MPI Ski engines from 2002-05 with serial number OM317000 and up.

Does the serial number of my engine matter when ordering this belt? Yes, serial number matters because MerCruiser MX 6.2L MPI engines switched belt part numbers at certain serial breaks. The 18-15121 belt covers OM310100 and up (MIE and Horizon MIE, standard cooling) and OM317000 and up (Ski), so confirm your engine's serial number before ordering.

What OEM part number does 18-15121 replace? Sierra 18-15121 replaces OEM number 57-865615005, so it is a direct cross-reference for engines that originally used that MerCruiser belt.

What is the 18-15121 belt made of? The belt is constructed with polychloroprene rubber and polyester fiber tensile members, giving it oil resistance and temperature stability for marine engine use.

How much does the Sierra 18-15121 serpentine belt weigh? The 18-15121 serpentine belt weighs 0.52 pounds.

Is this belt a genuine Sierra part or a generic aftermarket belt? Sierra 18-15121 is a Sierra-branded aftermarket belt built to OEM quality standards for correct fit, form, and function, rather than a generic universal belt.

Will this belt work on an engine with closed cooling? The 18-15121 belt is specified for MerCruiser MX 6.2L MPI MIE and Horizon MIE engines with standard cooling; MerCruiser used a different Sierra belt part number for the closed cooling versions of these engines.

What is the difference between 18-15121 and 18-15122? 18-15121 covers MerCruiser MX 6.2L MPI engines with serial OM310100 and up on standard cooling (MIE, Horizon MIE) plus Ski engines with serial OM317000 and up, while 18-15122 is the corresponding Sierra belt for the same engine families on closed cooling with serial OM317000 and up.

What is included when I order this belt? Each order includes one Sierra 18-15121 serpentine belt; no additional pulleys, tensioners, or hardware are included.

Is the 18-15121 a serpentine or V-belt design? It is a serpentine mount belt, meaning a single ribbed belt routes around multiple pulleys rather than using separate individual V-belts.

What color is the Sierra 18-15121 belt? The 18-15121 serpentine belt is white.

Where is the Sierra 18-15121 belt manufactured? The 18-15121 serpentine belt's country of origin is the United States.