Belt Tensioner Pulley – Fits MerCruiser 4.3-8.1L (Replaces 8M6500024, 865598)
Belt Tensioner Pulley – Fits MerCruiser 4.3-8.1L (Replaces 8M6500024, 865598) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Belt Tensioner Pulley – Fits MerCruiser 4.3-8.1L (Replaces 8M650002...
Product Details
This Belt Tensioner Pulley is designed for a range of MerCruiser inboard and stern drive engines, including 4.3L, 5.0L, 5.7L, 5.8L, 6.2L, and 8.1L V6/V8 models from 1996–2025. It is also compatible with General Motors 262 CID V6 (4.3L) and GM V8 small block 5.0L & 5.7L engine blocks.
It is a direct replacement for Mercury part numbers 8M6500024, 818382, and 865598, and interchanges with Sierra 710-8M6500024, Heurofosh 865598, and YiheoZux 8M6500024.
- Engineered for direct-fit installation.
- Constructed from a durable thermal resin housing.
- Features a smooth, flat pulley surface with a molded-in bearing.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury | 8M6500024 |
| Mercury | 818382 |
| Mercury | 865598 |
| Sierra | 710-8M6500024 |
| Heurofosh | 865598 |
| YiheoZux | 8M6500024 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For MerCruiser engines from 1996 to 2025, this pulley fits various V6 and V8 models. Note the special condition for the 454 7.4L model.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| MerCruiser | 4.3L | V6 | 4-Stroke | 1996–2025 | 8M6500024 | |
| MerCruiser | 5.0L | V8 | 4-Stroke | 1996–2025 | 8M6500024 | |
| MerCruiser | 5.7L | V8 | 4-Stroke | 1996–2025 | 8M6500024 | |
| MerCruiser | 5.8L | V8 | 4-Stroke | 1996–2025 | 8M6500024 | |
| MerCruiser | 6.2L | V8 | 4-Stroke | 1996–2025 | 8M6500024 | |
| MerCruiser | 8.1L | V8 | 4-Stroke | 1996–2025 | 8M6500024 | |
| MerCruiser | 454 | 7.4L V8 | 4-Stroke | 1996–2025 | 8M6500024 | For engines with V-Belt driven raw water pump with fuel pump |
Fits specific GM V6 and V8 engine blocks. Please verify your application.
| Brand | Model | Rated HP | Stroke | OEM Part No. | Notes |
|---|---|---|---|---|---|
| GM | 262 CID | V6, 4.3L | 4-Stroke | 865598 | Engine block parts |
| GM | Small Block | V8, 5.0 & 5.7L | 4-Stroke | 865598 | Engine block parts |
Technical Specs
- Product Type
- Serpentine Belt Tensioner Pulley
- Installation
- Direct replacement
- Housing Material
- Thermal resin
- Housing Color
- Black
- Dimensions
- Diameter: 3⅛" (79.4 mm), Bearing diameter: ⅝" (15.9 mm)
- Fitting Type
- Direct mount
- Other Attributes
- Smooth, flat pulley surface (no grooves), bearing is molded into the pulley
What’s in the Box
- 1 x Belt Tensioner Pulley (Replaces 8M6500024/865598/818382)
Installation Notes
- Disconnect the battery's negative terminal for safety.
- Locate the serpentine belt tensioner assembly on the engine.
- Use a tensioner tool or breaker bar to release the tension on the belt and slip it off the pulley.
- Unbolt and remove the old tensioner pulley.
- Install the new pulley, ensuring it is securely fastened to the specified torque.
- Route the serpentine belt back onto the pulley according to the engine's diagram.
- Reconnect the battery and start the engine to check for proper operation and listen for any unusual noises.
Troubleshooting & FAQ
How do I know if this pulley fits my engine?
Check the 'Engine & Model Compatibility' tables. This pulley fits a wide range of MerCruiser V6/V8 models (4.3L-8.1L) from 1996–2025 and certain GM engine blocks. Always verify your part number against the 'Part Number Matrix' to ensure an exact match.
What are the signs of a failing tensioner pulley?
Common signs include a squealing, chirping, or grinding noise from the engine bay, visible wobble or physical damage on the pulley, or a noticeably loose or frayed serpentine belt.
Is a special tool needed for installation?
A standard socket set and a serpentine belt tensioner tool (or a long-handled ratchet/breaker bar) are typically required to safely release the tension on the belt for removal and installation.
How does this aftermarket pulley differ from the OEM part?
This part is made from high-quality thermal resin, similar to the original, and is designed to meet or exceed OEM specifications for fit, form, and function. The primary difference is brand and price point, offering a cost-effective solution without sacrificing performance.
What is the recommended replacement interval?
While there is no strict interval, it is best practice to inspect the tensioner pulley during routine belt replacement (typically every 60,000 to 100,000 miles). Replace it if you notice any noise, wobble, or physical damage.
Can I replace just the bearing instead of the whole pulley?
No. The bearing is molded directly into the pulley housing as an integrated unit and is not designed to be serviced or replaced separately. The entire pulley assembly must be replaced.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, it is batch-inspected for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
This product is covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
Payment & Security
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