Sierra V-Belt 18-15550, 55 Inch, Fits 7.4L 454 MAG ALPHA 1986-1988 and 454 MAG 1988-92 Engines

The Sierra 18-15550 is a 55 inch V-belt built for marine engine service, designed to deliver OEM-quality fit, form, and function on applicable 7.4L 454 MAG engines. It is constructed with a synthetic fiber fabric cover, a special polyester cord, and a polychloroprene rubber body, giving the belt oil resistance and temperature stability for use in the demanding environment of a boat engine compartment. The polyester cord provides tensile strength to resist stretching under load, while the polychloroprene rubber compound resists cracking and glazing from heat cycling and exposure to engine fluids.

This belt is engineered as a drop-in replacement sized specifically for the 55 inch belt position on covered MerCruiser 454 MAG applications, so installers do not need to guess at length or cross-section. It fits the 7.4L 454 MAG ALPHA engine (454 cid, 8 cylinder, serial number range A631894 - B785148) and the 7.4L 454 MAG engine (454 cid, 8 cylinder, serial number range B721206 - D805068). Each belt ships as a single unit and is finished in white.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-15550
• Product Type: V-Belt
• Belt Length: 55 inches (1397 mm)
• Engine Displacement: 454 cid (7.4L)
• Engine Cylinders: 8
• Applicable Serial Number Range: A631894 - B785148 (454 MAG ALPHA); B721206 - D805068 (454 MAG)
• Weight: 0.31 pounds
• Color: White
• Material: Synthetic fiber fabric cover, polyester cord, polychloroprene rubber body
• Number of Items: 1
• UPC: 030999566744

Fitment

• 7.4L 454 MAG ALPHA, 1986-1988, 454 cid, 8 cylinder, serial number range A631894 - B785148
• 7.4L 454 MAG, 1988-92, 454 cid, 8 cylinder, serial number range B721206 - D805068

Frequently Asked Questions

What engines does the Sierra 18-15550 V-belt fit? The Sierra 18-15550 fits the 7.4L 454 MAG ALPHA engine (1986-1988, 454 cid, 8 cylinder, serial number range A631894 - B785148) and the 7.4L 454 MAG engine (1988-92, 454 cid, 8 cylinder, serial number range B721206 - D805068).

How long is the 18-15550 belt? This belt measures 55 inches (1397 mm) in length, sized for the 55 inch belt position on its covered MerCruiser 454 MAG applications.

What is the 18-15550 belt made of? It is built with a synthetic fiber fabric cover over a special polyester cord and a polychloroprene rubber body, giving the belt oil resistance and temperature stability.

Is the Sierra 18-15550 an OEM-quality belt? Yes, the 18-15550 is manufactured to be correct in fit, form, and function for its listed 454 MAG applications, matching OEM belt performance.

How do I know if my engine's serial number matches this belt? Check your engine's serial number against the ranges A631894 - B785148 for the 7.4L 454 MAG ALPHA or B721206 - D805068 for the 7.4L 454 MAG; the 18-15550 is built for engines within these ranges.

What color is the 18-15550 V-belt? The belt is white in color.

How many belts come in a package? Each package of the Sierra 18-15550 contains a single V-belt.

How much does the 18-15550 V-belt weigh? It weighs 0.31 pounds.

Does the 18-15550 resist heat and oil exposure? Yes, the polychloroprene rubber body and polyester cord construction give this belt oil resistance and temperature stability suited to a marine engine compartment.

Will the 18-15550 fit any 454 MAG engine, or just certain serial numbers? It is built for 7.4L 454 MAG and 454 MAG ALPHA engines within the specific serial number ranges A631894 - B785148 and B721206 - D805068; engines outside those ranges may require a different belt length.

What is the UPC for the Sierra 18-15550 belt? The UPC for the Sierra 18-15550 V-belt is 030999566744.