Sierra Marine V-Belt 18-15470 | 47 in. / 119.4 cm × 29/64 in. / 11.5 mm
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Sierra Marine V-Belt 18-15470
- Part Number: 18-15470 (Sierra)
- Brand: Sierra
- Product Type: Cogged Marine V-Belt
- Effective Length: 47 in. / 119.4 cm
- Top Width: 29/64 in. / 11.5 mm
- UPC: 030999566591
The Sierra 18-15470 is a cogged marine V-belt for selected MerCruiser and OMC inboard and sterndrive accessory-drive systems. High-strength synthetic cords resist stretching and shock-load failure. The precision-moulded cog profile improves flexibility and allows greater airflow around the belt. Rubber sidewalls provide positive, non-slip pulley contact.
Compatible Applications
Verified MerCruiser GM 454 CID / 7.4 L V8 applications:
- MerCruiser 330 — 1982–1987
- MerCruiser 340 / 7.4L MIE — 1981–1992
- MerCruiser 7.4L Bravo — 1988–1991
- MerCruiser 7.4L MIE with Hurth Transmission — 1989–1992
- MerCruiser 454 MAG Alpha — 1986–1988
- MerCruiser 454 MAG Bravo — 1988–1992
- OMC inboard/sterndrive applications specifying OEM belt 0509309
Always confirm engine model, serial number, existing OEM belt number, and accessory-drive configuration before ordering. Engines with the same displacement can use different belt lengths depending on pulley arrangement, alternator, and production year. Matching the OEM part number and belt width is more reliable than selecting by displacement alone.
Cross-Reference Part Numbers
- Sierra: 18-15470
- Supplier/Catalogue Reference: 47-15470
- Mercury / MerCruiser: 57-78200
- Mercury / MerCruiser: 57-78200A1
- Mercury Quicksilver: 57-78200Q1
- OMC: 0509309
- Redline: RL15470
Mercury documents 57-78200A1 as superseded by 57-78200Q1.
When to Replace This Belt
- Cracks visible between the cogs
- Frayed or worn edges
- Glazed, hardened, or oil-contaminated surface
- Increased belt dust around pulleys
- Slipping, squealing, or loss of tension
- Belt has stretched beyond adjustment range
Installation Notes
- Inspect pulley grooves for wear, corrosion, and alignment before installing
- Confirm correct belt routing for your engine configuration
- Do not force the belt over pulley flanges with sharp tools — this can damage internal cords
- Set belt tension to the engine manufacturer's specification
- Rotate the assembly by hand to confirm full pulley seating
- Recheck tension after initial operation
Parts Desk Insights
Best use case: This belt is the go-to for pre-season service and routine maintenance on MerCruiser and OMC inboard and sterndrive boats. If your engine specifies OEM references 57-78200, 57-78200A1, 57-78200Q1, or OMC 0509309, this is the direct replacement. It's also a practical onboard spare for extended cruising — a belt failure on these big-block engines can simultaneously disable raw water cooling and battery charging.
Common issue: Belt length alone is not enough to confirm fitment. Customers frequently order by engine displacement without checking the pulley arrangement or OEM number, which leads to slipping, overheating, or premature accessory-drive wear. Always match the original OEM belt number and verify the belt width and pulley configuration before ordering.
For a complete cooling system service, pair this belt with a raw water pump impeller. See the PCM Impeller Kit RP061017 and PCM / Crusader RP061022 Raw Water Pump Impeller for compatible options.
Need a different belt size? Browse other sizes in the Sierra V-Belt series: Sierra V-Belt 47-15400, Sierra V-Belt 47-15410, Sierra V-Belt 47-15440, Sierra V-Belt 47-15450, Sierra V-Belt 47-15455, Sierra V-Belt 47-15460, and Sierra V-Belt 47-15550.
Shop all Engine Parts & Maintenance or browse Propulsion & Powertrain for related components.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
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Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
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