Alternator for John Deere 4040-4850 & 8440-8640 Tractors - 12V 75 Amp
Alternator for John Deere 4040-4850 & 8440-8640 Tractors - 12V 75 Amp
SKU:400-52149
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Alternator for John Deere Tractors, Harvesters & Loaders
12-Volt, 75 Amp IR/EF - Replaces John Deere AR87204 / TY6621
This alternator is a direct replacement for the original high-output unit fitted to John Deere 4000 and 8000 Series farm tractors, 5720-5830 harvesters, 444D/544D/644D loaders and the 7445 cotton picker. It supersedes John Deere part numbers AR87204 and TY6621, and is manufactured to OEM specifications for fit, form and function, so it installs in place of the original part without modification.
The unit is rated 12-volt, 75-amp with clockwise rotation, an internal regulator (IR) and external fan (EF), in the Denso design used as original equipment. It uses a 2-groove (V2) pulley with a 17mm ID, designed to run on a 1/2 inch belt. The external fan design assists cooling under the sustained higher-amperage loads a working tractor's electrical system can draw. Please note this unit does not support an indicator light circuit.
Key Features
- 12-volt, 75-amp high output
- Clockwise (CW) rotation, Denso design
- Internal regulator (IR), external fan (EF)
- 2-groove V2 pulley, 17mm ID
- 1/2 inch belt width
- Does not support an indicator light circuit
Technical Specs
| Specification | Detail |
|---|---|
| Voltage | 12V |
| Amperage | 75A |
| Rotation | CW (clockwise) |
| Manufacturer | Denso |
| Pulley Type | V2 (2-groove), 17mm ID |
| Belt Width | 1/2 inch |
| Fan Type | EF (external) |
| Regulator Type | IR (internal) |
Vehicle Fitment Guide
Years shown are the overall coverage span for this part. Please confirm against the OEM part number on your original unit before ordering.
| Make & Model | Years |
|---|---|
| John Deere 4040 Tractor (JD 6-404 diesel) | 1981-1982 |
| John Deere 4050 Tractor (JD 6-359 / 6-466 diesel) | 1983-1988 |
| John Deere 4240, 4440, 4640 Tractors (JD 6-466 diesel) | 1981-1982 |
| John Deere 4250, 4650, 4850 Tractors (JD 6-466 diesel) | 1983-1988 |
| John Deere 4350 Tractor (JD 6-466 diesel) | All model years |
| John Deere 4450 Tractor (JD 6-466 diesel) | 1983-1990 |
| John Deere 4840 Tractor (JD 6-466 diesel) | 1979-1982 |
| John Deere 8440 Tractor (6-466 diesel) | 1979-1982 |
| John Deere 8630 Tractor (6-619 diesel) | 1978-1980 |
| John Deere 8640 Tractor (6-619 diesel) | 1979-1982 |
| John Deere 5720, 5820 Harvesters (466 / 619 diesel) | 1982-1986 |
| John Deere 5730, 5830 Harvesters (466 / 619 diesel) | 1986-1992 |
| John Deere 444D, 544D, 644D Loaders | 1987-1988 |
| John Deere 7445 Cotton Picker (359 diesel) | 1987-1994 |
OEM Part Number Cross Reference
Aftermarket replacement. OEM part numbers are listed for reference only.
| Part Number | Manufacturer / Brand |
|---|---|
| AR87204, AR87205, AR93447, AR93448, AT103789, AT103798, SE501363, TY6621, TY26050 | John Deere |
| 021000-7410, 021000-7420, 021000-8741, 100211-0070, 100211-0080, 100211-0280, 100211-0290, 100211-0790 | Denso |
| AND0002, ND021000-7410, ND021000-8741, ND100211-0081, ND100211-0280 | Arrowhead |
| 13143, 14523 | Lester |
| 13143N, 1-2236-10ND | WAI |
| LRA01229 | Lucas Electrical |
| 110445 | Cargo |
| 50903 | Remy Light Duty |
| 400-52149 | J&N Electrical Products |
Frequently Asked Questions
Will this fit my John Deere tractor without modification?
Yes, this unit is manufactured to OEM specifications and bolts directly into the standard mounting points on the models listed above.
What's included?
The alternator unit only.
How can I tell my alternator has failed?
Signs include a charge warning light, a battery that will not hold charge, dimming lights, or unusual noise from the unit.
How do I confirm this is the correct alternator?
Check the number on your original unit against the table above - John Deere AR87204 or TY6621, or Denso 021000-7410, are the most common.
Why does this unit use an external fan instead of an internal one?
The external fan (EF) configuration matches the original equipment design used on this higher-output alternator, providing cooling suited to the sustained 75-amp load.
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