Sierra — Cogged Marine V-Belt 44 in. (111.8 cm) x 29/64 in. (11.5 mm) — 18-15440
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
Sierra Marine V-Belt 18-15440 — 44 in. (111.8 cm) x 29/64 in. (11.5 mm)
The Sierra 18-15440 is a cogged marine V-belt built for the accessory-drive system on selected older MerCruiser and OMC inboard and sterndrive engines. Its cogged construction improves flexibility and cooling airflow, while high-strength synthetic cords and a low-stretch design help the belt hold tension and deliver reliable power to the alternator and water pump.
Compatible Applications
- MerCruiser 233 / 233 MIE applications
- MerCruiser 898 / 200 / 5.0L applications
- MerCruiser 250, 255 and 260 / 5.7L applications
- Additional older MerCruiser V-belt configurations where this belt is specified for the alternator/water-pump drive
- OMC inboard and sterndrive applications cross-referencing OMC 311046
Serial Number Fitment Notice
Do not select this belt by engine displacement alone. Engines of the same horsepower or displacement can use different belt lengths depending on serial number, pulley diameter, power steering, raw-water versus fresh-water cooling, and accessory layout. If you are unsure which belt your engine needs, match the existing belt number or confirm your engine model and serial number before ordering.
When This Part Needs Replacement
- Cracking, glazing or hardened rubber
- Frayed or damaged belt edges
- Missing or damaged cog sections
- Excessive stretching or difficulty maintaining proper tension
- Belt squeal or slipping after correct tension adjustment
- Contamination from oil, coolant or other fluids
A worn accessory belt can reduce alternator, circulating-pump or other belt-driven accessory performance.
Installation Notes
Confirm that 18-15440 is specified for the exact pulley and accessory configuration before installation. Inspect pulley grooves for corrosion, damage or contamination and verify pulley alignment. Set belt tension according to the engine manufacturer's service procedure — excessive tension can overload accessory bearings, while insufficient tension can cause slipping and premature belt wear. When replacing multiple belts on the same drive system, check each one independently, since similar configurations can use different belts for the alternator/water pump, power steering and seawater pump.
Alternate/Superseded Part Numbers
- Mercury / MerCruiser 57-93658Q
- Mercury / MerCruiser 57-93658
- Mercury / MerCruiser 57-49213
- Mercury / MerCruiser 57-49213A1
- Mercury / MerCruiser 57-45856
- OMC 311046
- Mallory 9-55006
Mercury's current 57-93658Q 44-inch V-belt is listed as equivalent to Sierra 18-15440.
Technical FAQ
Will this fit any MerCruiser with a 5.0L or 5.7L engine? Not automatically — belt length depends on pulley size and accessory layout, which can differ even within the same engine family. Confirm against your existing belt or engine serial number.
Can I use this in place of the OMC 311046 belt? Yes, for OMC inboard and sterndrive applications where 311046 is specified, 18-15440 is a verified cross-reference.
Parts Desk Insights
Best use case: This belt is best suited to spring commissioning and routine accessory-drive service on the older MerCruiser and OMC engines listed above, where the alternator and water pump share a single drive belt.
Common mistake: The most frequent ordering mistake is choosing this belt by engine displacement or horsepower alone. Two engines in the same family can call for different belt lengths depending on pulley size and accessory setup, so matching displacement alone can leave you with a belt that looks right but won't tension correctly.
Sizing and fitment guidance: If you are replacing a belt that's still identifiable, match its part number directly. If the old belt number is worn away, confirm your engine model and serial number against the applications above before ordering, since pulley diameter and accessory configuration change which belt length is correct.
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.
To qualify for a return:
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:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.