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Yanmar 129908-77200 is the 12 V, 80 A alternator with a single groove pulley, two mounting ears and an adjusting arm. It is used on Yanmar 4TNV98 engines. This aftermarket version has the same mounting and electrical connector as the original, so it plugs in and bolts on where the old one came off.
Sold as one unit. Check the number on your old part, or in the parts manual for your machine, before ordering.
| Part Type | Alternator |
| Replaces | Yanmar 129908-77200 |
| Voltage | 12 V |
| Output | 80 A |
| Engine | Yanmar 4TNV98 |
| Fits | Yanmar 4TNV98 engines, including Yanmar TT series tractors |
| Condition | New, aftermarket |
| Stat. HS-Code | 851150 |
| Country of Manufacture | China |
Yanmar machines
Check the part number on your old unit before ordering.
| Yanmar Part No.(SPM Part No.) | Fits |
|---|---|
| 129908-77200(SPM-HEP-4667) | Yanmar 4TNV98 engines, including Yanmar TT series tractors |
| 12990877200(SPM-HEP-4667) | Yanmar 4TNV98 engines, including Yanmar TT series tractors |
Battery not charging
A charge warning light or flat batteries every morning point to the alternator once the belt and wiring check out.
Noise
A worn bearing whines or grinds.
Low voltage at idle
Weak output shows as dim lights and slow electrics at idle.
Fit with a new belt
Change the belt and check the tensioner when fitting the alternator.
We check what other aftermarket sellers charge for this same part. Their prices on the date we checked:
| Seller | Price | Checked |
|---|---|---|
| eBay, aftermarket seller | USD 189.59 | 31 Oct 2026 |
| Start Motor & Alternators (UK) | USD 198.17 | 31 Oct 2026 |
| Yem Parts | USD 246.42 | 31 Oct 2026 |
| Fab Heavy Parts | USD 252.01 | 31 Oct 2026 |
| SINOCMP | USD 259.00 | 31 Oct 2026 |
| Spare Part Mart | USD 148.45 | Today |
Our price of USD 148.45 is 22% to 43% less than these sellers.
Found this part cheaper somewhere else? Send us the listing and we will beat it by 5% under our Price Beat Guarantee. Every order is also covered by our 30 day money back guarantee.
Yes, it is a direct replacement for the Yanmar 129908-77200 with the same fitting.
Typically 5,000 to 10,000 hours, depending on how often the machine is started and how well the batteries are kept.
A charge warning, low battery voltage with the engine running, flickering lights or bearing noise.
Disconnect the battery earth before removing the old unit. The main cable is live at full battery current.
Check the old unit before you send it away. Pulleys and fans are often fitted to suit the machine and have to be moved across.
No. It is an aftermarket alternator made to replace the Yanmar 129908-77200. It is not made by the original manufacturer; the number only shows what it replaces.
Live rates for the quantity selected, delivered to your door. Confirmed at checkout.
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Join Marty Mates and we put 200 points on your account, worth $10 off an order over $75 USD. Then a point for every dollar you spend after that.
No password: you enter your email, we send a code, and that is you in.
