John Deere 8420 Tractor Parts
8420 parts and accessories
The John Deere 8420 tractor, manufactured from 2002 to 2005, was a popular choice among farmers for its power and reliability. Powered by a robust John Deere PowerTech 8.1L diesel engine producing around 225 engine horsepower, the 8420 delivered impressive performance. With a PTO horsepower rating of approximately 185, it was well-suited for a variety of demanding agricultural tasks, making it a versatile workhorse on any farm.
The John Deere 8420 was part of the 20 Series tractors, introduced in 2002 as an upgrade from the previous John Deere 8010 Series. Production continued until 2005. The heart of the 8420 is a John Deere PowerTech 8.1L (496 cu in) six-cylinder turbocharged diesel engine. This engine delivers a rated 225 horsepower (gross) and around 185 PTO horsepower. The engine is known for its durability and efficient fuel consumption. Transmission options included the standard 16-speed PowerShift transmission, or the optional Infinitely Variable Transmission (IVT) for smooth, clutchless operation. The PTO features both 540 and 1000 RPM options, catering to various implement requirements. The closed-center hydraulic system offers a flow rate of approximately 41 GPM, providing ample power for hydraulic implements. The three-point hitch is a Category III/IIIN, capable of lifting around 10,500 lbs. The John Deere 8420 was commonly used for row crop operations, hay production, livestock management, and primary tillage. It distinguished itself from other models in the lineup with its increased horsepower and advanced features, bridging the gap between the smaller 8020 series and the larger, more powerful 9000 series tractors.
Specifications
| Engine | John Deere PowerTech 8.1L 225 HP Diesel |
|---|---|
| PTO HP | 185 HP @ 1000 RPM |
| Transmission | PowerShift, 16-speed |
| Hydraulics | 41 GPM, 3-4 remotes |
| 3-Point Hitch | Category III/IIIN, 10,500 lbs |
| Fuel Capacity | 150 gallons |
| Weight | 20,500 lbs |
| Years Produced | 2002-2005 |
Maintenance Tips
- Check engine oil and filter regularly, typically every 250-500 hours, using John Deere-approved oil and filters for optimal engine life.
- Inspect hydraulic fluid levels and filters every 500 hours, replacing filters as needed to prevent contamination and ensure proper hydraulic system performance.
- Maintain the fuel system by using clean fuel and changing fuel filters regularly (every 500 hours), draining any water from the fuel tank to prevent injector damage.
- Before seasonal storage, fill the fuel tank to prevent condensation, lubricate all grease fittings, and disconnect the battery to prevent discharge.
History & Background
The John Deere 8420 was introduced in 2002 as part of the redesigned 8020 series, replacing the 8410 model. It offered increased power and updated styling compared to its predecessor. The 8420 played a significant role in modern agriculture by providing farmers with a reliable and technologically advanced tractor for a wide range of tasks.
Frequently Asked Questions
What engine is in the John Deere 8420?
The John Deere 8420 is equipped with a John Deere PowerTech 8.1L (496 cu in) six-cylinder turbocharged diesel engine, producing 225 horsepower.
What is the PTO horsepower on a 8420?
The PTO horsepower on the John Deere 8420 is approximately 185 HP, typically at 1000 RPM, but it also has a 540 RPM option.
What oil filter fits the 8420?
The recommended oil filter for the John Deere 8420 is a John Deere filter part number RE504836. Common cross-references include Baldwin B7344 and Wix 57712.
What are common parts needed for the 8420?
Commonly needed parts for the John Deere 8420 include engine oil filters, fuel filters (John Deere RE522878), hydraulic filters (John Deere RE62419), fan belts, hydraulic cylinder seal kits, steering cylinder repair parts, and clutch components like discs and pressure plates.

OK504202 - MAJOR OH KIT
SKU: OK504202
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MX1062 - Oil Pump (Crank Driven) Repair Kit
SKU: MX1062
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IK504202 - IN FRAME OH KIT
SKU: IK504202
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DZ114591 - Oil Cooler Gasket
SKU: DZ114591
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AR98850 - O-Ring Kit
SKU: AR98850
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AR55394 - Oil Cooler
SKU: AR55394
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AR49025 - Front Crankshaft Seal
SKU: AR49025
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A4827R - Drain Plug (10 pk) Gasket
SKU: A4827R
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RE70957 - (Gear Reduction) Nippo. Starter
SKU: RE70957
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RE68495 - Auxiliary Power Outlet
SKU: RE68495
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RE68327 - 40 Amp Relay Module
SKU: RE68327
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RE67014 - Power Strip Harness Adapter
SKU: RE67014
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RE67013 - Auxiliary Power Cord
SKU: RE67013
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RE61717 - Ignition Switch
SKU: RE61717
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RE519144 - Engine Speed Sensor; Magnetic Pickup
SKU: RE519144
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RE51091 - Auxiliary Power Outlet
SKU: RE51091
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RE49778 - Lamp; 26.88 Watt Bulb
SKU: RE49778
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RE37651 - 3 Pin Auxiliary Power Cord
SKU: RE37651
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RE262484 - 9 Pin Block Module Diode
SKU: RE262484
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RE261354 - Contacting Potentiometer Sensor
SKU: RE261354
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RE218703 - Bosch Type 150 Amp 12 Volt Alternator; IR/IF
SKU: RE218703
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RE164448 - 12 Volt Starter Relay
SKU: RE164448
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R39554 - Horn (12 Volt) Ether Ignition Switch
SKU: R39554
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AT68973 - Relay Solenoid Switch
SKU: AT68973
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