Alternator Belt – Fits Yanmar 1GM10 (Replaces 128170-77350)
Alternator Belt – Fits Yanmar 1GM10 (Replaces 128170-77350) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Alternator Belt – Fits Yanmar 1GM10 (Replaces 128170-77350)
Product Details
This aftermarket Alternator Belt – Fits Yanmar 1GM10 Marine Diesel Engine (Replaces 128170-77350) is designed for single-cylinder Yanmar 1GM10 marine diesel engines (9 HP, 4-stroke) manufactured between 1983 and 2009. It serves as the essential accessory belt driving the alternator and water pump.
It directly replaces Yanmar part numbers 128170-77350 and 128170-77350E, as well as several aftermarket equivalents including Gates 6560MC, AVX11.5x790, AVX11x790, Mitsubishi REMF 1305, and Nissan 11720-83075-1.
- Constructed from durable rubber with fiber reinforcement for longevity.
- Installs as a continuous loop V-belt for the engine's accessory drive.
- Package includes one alternator and water pump belt.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket brands.
| Brand | Part Number |
|---|---|
| Yanmar | 128170-77350 |
| Yanmar | 128170-77350E |
| Gates | 6560MC |
| Generic | AVX11.5x790 |
| Generic | AVX11x790 |
| Mitsubishi | REMF 1305 |
| Nissan | 11720-83075-1 |
Engine & Model Compatibility
Confirm your engine model and year in the tables below. Be aware that two different belt sizes were used on these engines; measuring your existing belt is the best way to ensure a match.
This belt fits the following Yanmar marine engines:
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yanmar | 1GM | 7.5 | 4-Stroke | 1980–1983 | 128170-77350 | Early model |
| Yanmar | 1GM10 | 9 | 4-Stroke | 1983–2009 | 128170-77350 | For engines with serial numbers up to E03690 |
| Yanmar | 1GM10C | 9 | 4-Stroke | 128170-77350 | Saildrive version | |
| Yanmar | 1GM10VE | 9 | 4-Stroke | 128170-77350 |
An alternate, longer belt is available for later model 1GM10 engines, often those fitted with a larger alternator pulley.
| Brand | Model | Rated HP | Stroke | OEM Part No. | Notes |
|---|---|---|---|---|---|
| Yanmar | 1GM10 | 9 | 4-Stroke | 105582-77790 | 788-790mm length - Alternate belt for later models |
Technical Specs
- Product Type
- V-Belt / Alternator Belt / Water Pump Belt
- Installation
- Engine accessory belt for alternator and water pump
- Connection
- Continuous loop belt
- Housing Material
- Rubber with fiber reinforcement
- Housing Color
- Black
- Dimensions
- 737mm (29") length for early models, 790mm length for later models
- Weight
- 0.62 kg (1.37 lb)
- Fitting Type
- V-Belt
- Warranty
- 1 year (aftermarket)
- Other Technical Attributes
- Belt deflection should be approximately 1 cm (½") under moderate thumb pressure
What’s in the Box
- 1 x Alternator Belt (replaces 128170-77350)
Installation Notes
- Disconnect the battery or main power switch for safety.
- Loosen the alternator's pivot and tensioning bolts.
- Push the alternator towards the engine to create slack and remove the old belt.
- Inspect pulleys for wear or damage before installing the new belt.
- Place the new belt over the pulleys, ensuring it is correctly seated in the V-grooves.
- Pry the alternator away from the engine to tension the belt. Proper tension is typically a 1 cm (½") deflection under moderate thumb pressure at the longest span.
- Tighten the tensioning and pivot bolts securely.
- Reconnect power and start the engine to check for proper operation.
Troubleshooting & FAQ
How do I know which belt size I need for my Yanmar 1GM10?
The Yanmar 1GM10 used two different belt sizes during its production run. Early models typically use a 737mm belt (our part 128170-77350), while later models or those with a larger alternator pulley use a longer 788-790mm belt. The most reliable method is to measure your old belt or check its part number before ordering.
What are the signs of a failing alternator belt?
Common symptoms include a loud squealing sound from the engine, visible cracks or fraying on the belt, a battery that won’t stay charged, or an overheating engine if the belt also drives the water pump.
How often should I replace the alternator belt?
Most marine engine manufacturers recommend inspecting the belt annually and replacing it every 2-4 years or every 500-1000 hours, depending on operating conditions. Consult your engine's service manual for specific intervals.
Can I install this belt myself?
Yes, replacing an alternator belt is a common maintenance task for boat owners with basic mechanical skills. The process involves loosening the alternator, swapping the belt, and re-tensioning it. However, if you are unsure, professional installation is recommended.
Will this belt fit a Yanmar 1GML or 1GM10C?
This belt is listed as compatible with the 1GM10C (Saildrive version). However, data for the 1GML is incomplete. We strongly recommend verifying the part number or dimensions from your existing belt before ordering for these models.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
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.
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