John Deere 8420 Specs, Weight, Engine, Parts, Attachments, Data, HP, Price and Problems

John Deere 8420 tractor was designed in 1984 and it was released to the public that same year. It is available in both 6×6 and 8×8 configurations. The engine used in this tractor is a diesel engine which provides a high level of power and efficiency. The 8420 also comes with several features that make it a very popular choice among farmers and ranchers. These features include its large tires, its easy-to-use controls, and its durable construction.

John Deere 8420 Specifications:

Weight (shipping)21,650 lbs or 9820 kg
Weight (operating)23,780 lbs or 10786 kg
ILS Weight (shipping)23,050 lbs or 10455 kg
Height (cab)122.2 in. (310 cm)
Front axle4WD Independent Link Suspension (ILS)
Engine typeFour-stroke, liquid-cooled, inline
Engine modelJohn Deere
Drawbar capacity3,900 lbs (1769 kg) (Cat 3 extended)
Displacement8.1 L, 8,128 cm2, (496.0 cu·in)
Bore and stroke116.0 mm X 129.0 mm or 4.57 in X 5.08 in
AG front tires16.9R30
AG rear tires18.4R46
BrakesHydraulic wet disc
Chassis4×4 MFWD 4WD
Front tread size60 to 80 in.
Gears16 forward and 4 reverse
Ground clearance
Height122.2 in. [310 cm]
Length211.9 in. [538 cm]
SpeedForward: 39.9 kmh (24.8 mph) Reverse: 10.9 kmh (6.8 mph)
Steering typeHydrostatic power
Transmission modelJohn Deere PowerShift
Transmission oil capacity140.1 L (37.0 US. gal, 30.8 Imp. gal.)
Transmission typeFull power shift with hydraulic wet disc clutch
Wheelbase118.9 in. [302 cm]
Starter volts12
Rated RPM2200
Rated Power (ECE R24)270 hp / 201.3 kW
Operating RPM1500-2200
Oil change250 h
Oil capacity28.5 qts (27.0 L)
Idle RPM900-2300
Fuel systemelectronic high-pressure common rail (HPCR)
EmissionsTier II
Coolant capacity35.9 qts / 34.0 L
Bore/Stroke4.56×5.06 in. (116 x 129 mm)
Air cleanerdry with secondary element
Compression ratio16.5:1
Engine size496 ci or 8.1 L
Engine torque
Engine torque RPM
Fuel injection systemelectronic high-pressure common rail (HPCR)
Fuel tank capacity160 gal or 605.6 L
Fuel typediesel
Horsepower314 hp or 234.1 kW
Maximum Power (EC 97/68)314 hp / 234.1 kW
Maximum Power (ECE R24)300 hp / 223.7 kW
Number of cylinders6 cylinders
Power RPM2200 (rpm)
Rated Power (EC 97/98)284 hp / 211.8 kW
Valves4 to 5
Total flow42.5 gpm (160.9 lpm)
SCV flow30.0 gpm (113.6 lpm)
Pressure2900 psi (199.9 bar)
Oil tank capacity28.5 qts or 27.0 L
Number of batteries2
Hydraulic typeClosed center pressure-flow compensated (PFC)
Engine starter volts12V
Electric ground forcenegative
Electric charging systemalternator
Electric charging Amps150 amps
Bore stroke4.56×5.06 in. or (116 x 129 mm)
Battery voltage12 V
Battery cold cranking Amps925


John Deere 8420 is a great tractor for the money. It has a lot of features that make it ideal for the average farmer or landowner. Between its powerful engine and comfortable ride, this machine is sure to get the job done. If you’re in the market for a reliable tractor, this is one that we would recommend.

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