Serpentine Belt 865615Q06 18-15102 for MerCruiser 350 377 5.0L MPI Alpha Bravo
Serpentine Belt 865615Q06 18-15102 for MerCruiser 350 377 5.0L MPI Alpha Bravo
Product Overview
Serpentine belt for Mercury MerCruiser V8 stern drive engines, the single belt that turns the alternator and the circulating pump on the 350, 377 and 5.0L MPI motors. It replaces 865615Q06, 865615006, 8638766 and 8610491, crosses to Sierra 18-15102, and it ships in a 20 x 25 x 5 cm box.
Fitment is by serial number, not by year. The 350 MPI Alpha, the 350 MAG MPI and Horizon in Alpha and Bravo trim, the 377 MAG MPI Bravo and the 5.0L MPI all use this belt in their later serial ranges, and the table below gives the break points so you can check yours before ordering.
These belts sit at the front of the engine where the raw water pump throws spray and the alternator loads them every time you come off the throttle. A glazed belt starts squealing on a cold start, then the ribs go glossy and it lets go with no spare on board, which leaves you with no charging and a motor that overheats inside a few minutes.
Specifications
| Specification | Detail |
|---|---|
| Condition | New / New with tags |
| Type | Serpentine belt, alternator and circulating pump drive |
| Fits | MerCruiser 350 MPI, 350 MAG MPI, 377 MAG MPI, 5.0L MPI |
| Drives | Alternator, circulating pump |
| Replaces | 865615Q06, 865615006, 8638766, 8610491 |
| Contents | 1 serpentine belt |
| Net Weight | 300 g including packaging |
| Pack Size | 200 mm x 250 mm x 50 mm |
| Warranty | 3 year |
OEM Cross Reference
| Component | OEM Part Numbers |
|---|---|
| Serpentine belt | 865615Q06 |
| Serpentine belt, alternate | 865615006 |
| Serpentine belt, earlier | 8638766, 8610491 |
| Sierra cross reference | 18-15102 |
Compatible Engines
| Engine | Horsepower | Drive | Serial Range |
|---|---|---|---|
| 350 MPI | 300 HP | Alpha | 1G400000 and up |
| 350 MAG MPI | 300 HP | Alpha / Bravo | 1A623185 and up |
| 350 MAG MPI | 300 HP | Alpha / Bravo | 1A611928 thru 1A623184 |
| 350 MAG MPI EC | 300 HP | Alpha / Bravo | 1A300000 thru 1A611927 |
| 350 MAG MPI Horizon EC | 300 HP | Alpha / Bravo | 1A300000 and up |
| 377 MAG MPI | 320 HP | Bravo | 1A623185 and up |
| 377 MAG MPI EC | 320 HP | Bravo | 1A343300 thru 1A611927 |
| 5.0L MPI | 260 HP | Alpha / Bravo | 1A623185 and up |
| 5.0L MPI EC | 260 HP | Alpha / Bravo | 1A300000 thru 1A611927 |
What's Included
| Component | Detail | Qty |
|---|---|---|
| Serpentine belt | 865615Q06 pattern, ribbed | 1 |
| Idler pulley | Not included, check it while the belt is off | 0 |
| Tensioner | Not included, replace it if it is weak | 0 |
| Alternator and pump | Not included | 0 |
Signs The Belt Is Due
| What You See | What It Means | What To Do |
|---|---|---|
| Squeal on a cold start | Belt glazed or tensioner weak | New belt, check the tensioner |
| Ribs cracked or missing | Rubber aged out | Change it before it lets go |
| Black dust in the front of the engine | Belt slipping on the pulleys | New belt and check alignment |
| Battery light flickers at idle | Alternator slipping | New belt and check the tension |
| Overheat at low speed only | Circulating pump not driven | New belt, inspect the pump pulley |
| Edge of the belt frayed | Pulley out of line or a bad bearing | Find the bad pulley, then fit the belt |
Fitting Notes
| Step | Action |
|---|---|
| 1 | Write down the engine serial number, the fitment is by serial range |
| 2 | Disconnect the battery and take a photo of the belt routing |
| 3 | Release the tensioner and slip the old belt off the pulleys |
| 4 | Spin every pulley and the idler by hand, listen for a dry bearing |
| 5 | Check the ribs of the new belt against the old one before fitting |
| 6 | Route the new belt from the photo and take up the tension |
| 7 | Turn the engine over by hand and confirm the belt sits centred |
| 8 | Run the engine and check the belt tracks true on every pulley |
Condition & Warranty
| Item | Detail |
|---|---|
| Condition | New / New with tags |
| Warranty | 3 year |
| Packaging | Sealed retail packaging |
Before You Buy
- Fits MerCruiser 350 MPI, 350 MAG MPI, 350 MAG MPI Horizon, 377 MAG MPI and 5.0L MPI
- Replaces 865615Q06, 865615006, 8638766 and 8610491
- Crosses to Sierra 18-15102
- Check the engine serial number against the range table, not just the model year
- Tensioner and idler pulley are not included
- Drives the alternator and the circulating pump on Alpha and Bravo drives
- 30-Day Easy Returns
- Ships from our warehouse with tracking
Verfügbarkeit für Abholungen konnte nicht geladen werden
Boat Owners' Review
Before You Buy
Frequently Asked Questions
What is your refund policy?
We offer a 14-day hassle-free return on all products. Items must be unused and in original packaging. Every XRmarine part is also covered by our 1-year warranty against manufacturing defects. If something is not right, email us at info@xrmarineparts.com — replacement or full refund, your choice.
See our full Refund Policy for complete details.
How does shipping work?
Free international shipping on every order — no minimums. We operate a global warehouse network with a main distribution centre in Asia (10-20 business days). We also hold stock in regional warehouses across the United States, Germany, the United Kingdom, Australia, and Poland (opening soon) — most orders arrive in 1-3 business days within those countries and in 2-8 business days to nearby regions. Tracking included.
See our full Shipping Policy.
How do you keep prices fair?
We cut out the middlemen. XRmarine sources directly from quality manufacturers and sells at honest prices. Same OEM-quality parts, no dealership markup. Every order comes with free shipping, real expert support, and a 1-year warranty.
Learn more on our About Us page.
What payment methods do you accept?
We currently accept PayPal — a fast, secure way to pay online. Credit card payments (Visa, Mastercard, American Express) and Shopify Payments are being set up and will be available soon. We appreciate your patience.