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John Deere 2120 Troubleshooting

The John Deere 2120 tractor was manufactured between 1969 and 1972. The JD 2120 powerline components: John Deere four stroke 4-cylinder direct injection liquid-cooled diesel engine and 8x4 unsynchronized gear transmission, or two-speed power shift transmission with 16 forward and 8 reverse gears.

A 219 cubic inches (3.6 L) engine has a cylinder bore of 4.02" (102 mm), piston stroke of 4.33" (110 mm), rated power of 68 hp (50.7 kW), and maximum torque of 69.6 Nm (51.3 lb-ft) at 1500 rev/min. Max. forward speed - 18.6 mph (29.9 kph), max. reverse speed - 8.1 mph (13 kph).

The closed center hydraulic system used a piston pump with a flow rate of 12.4 gal/min (46.9 liters per minute). The hydraulic pressure is 155 bar (2250 psi). The John Deere 2120 is equipped with a power assist steering, differential hydraulic wet disc brakes, 7.50x16 front tires and 15.5x38 rear tires. The wheelbase is 86 inches (2180 mm).

Engine Troubleshooting
Engine won't start or hard to start
Clogged fuel filter element - Clean the filter or install new filter element
Fuel shut-off valve closed - Open the fuel shut-off valve
Water, dirt, or air in fuel system - Drain, flush, fill, and bleed system
Fuel injectors are damaged or dirty - Change fuel injectors
Fuel injection pump is defective - Repair or change injection pump
Engine has bad compression - Check cylinder block and replace defective parts
Engine stops during operation
Engine has not warmed up to the recommended temperature - Warm up engine as required
Air in fuel lines - Bleed fuel lines
Fuel injection failed - Use correct settings
Fuel filter clogging - Service the filter
Dirty or faulty injectors - Service or change fuel injectors
Engine starts but immediately shuts off
Unadjusted fuel injection pump timing - Check the fuel injection pump timing setting
Clogged fuel filter element - Change filter element
Dirty or defective injector nozzles - Change injector nozzles
Fuel injection pump is broken - Change or repair the pump
Air cleaner clogging - Replace or service air cleaner element
Engine stops when idling
Incorrect low idle speed adjustment - Correct low idle settings
Defective fuel injection pump - Install a new fuel pump or repair
Dirty or defective injector nozzles - Install new set of properly balanced nozzles
Valve clearance is not correct - Adjust valve clearance
Engine overheated
Lack of coolant in cooling system - Fill the radiator to the required level. If there are leaks in the system, replace worn components
Cooling system parts are damaged or system is dirty - Change faulty components or flush the cooling system
Insufficient engine oil - Check and refill engine oil
Damaged fan belt or incorrect belt tension - Adjust belt tension properly or replace it
Thermostat failure - Install new thermostat
Poor engine power
Fuel injectors are clogged or faulty - Service or change fuel injectors
Improper fuel injection pressure - Adjust pressure to proper level
Air filter is clogged - Air filter maintenance required
Oil filter is clogged - Change or clean engine oil filter element
Engine is running overloaded - Load reducing required
Valve clearance is out of adjustment - Need to adjust valve clearance
Incorrectly adjusted low idle speed - Correct low idle settings
Fuel hoses or pipes are clogged - Fuel hoses and pipes must be clean
Engine low compression: Leaking or faulty valves - Have valves replaced
Engine knocking sound or abnormal noise
Incorrectly set fuel injection pump timing - Adjust the fuel injection pump timing correctly
Fuel injector nozzles are dirty or defective - Service or replace injector nozzles
Engine oil insufficient - Add oil to the engine crankcase
Low coolant temperature - Warm up to required temperature
Main bearings or crankshaft wear - Crankshaft or bearings need to be replaced
Piston rings are defective or broken - Piston rings replacement required
Loose flywheel screws - Check the flywheel screws and tighten as required
Engine consuming too much oil
Oil leaking: Worn seals or gaskets - Defective components must be replaced
Oil viscosity is wrong - Use correct viscosity oil
Piston rings are stuck or broken - Have piston rings replaced
Worn valve stems and valve guides - Need to replace the valves
Pistons or cylinder liners are scuffed - Check pistons and liners, change as required

Electrical System Troubleshooting
Battery will not charge
Battery is defective - Battery replacement required
Damaged battery wiring harness - Inspect wiring for damage, replace or repair
Loose or corroded battery terminals and cables - Tighten or clean terminals and cables
Belt damage or incorrect belt tension adjustment - Replace belt or adjust belt tension correctly
Starter motor cranks slow
Battery voltage is low - Battery needs to be recharged
Battery discharges quickly - Service charging system or replace battery
Bad battery electrical wire harness - Check wires for malfunctions, repair or replace
Loose or corroded battery terminals and cables - Clean or tighten terminals and cables
Starter motor won't turn
Battery voltage is low - Low battery charging, charge as required
Discharged or faulty battery - Charge or change the battery
Starter motor failure - Repair or replace starter
Disconnected or incorrectly connected cables - Need to reconnect cables correctly

Transmission Troubleshooting
Hard shifts
Failure or improper clutch adjustment - Adjust or change the clutch
Damaged or loose gear shift linkage - Replace or repair the shift linkage
Damaged or worn shift forks - Shift forks need to be replaced
Faulty parts in the gear shifting mechanism - Change faulty parts
Transmission fluid pressure is insufficient
Fluid level is low - Check and refill the transmission fluid
Transmission oil filter element is dirty (if fitted) - Replace or clean transmission oil filter
Relief valve sticking - Replace relief valve
Transmission is making noise
Broken or worn bearings - Replace faulty bearings
Not enough fluid in transmission - Fill the transmission housing with fluid
Contaminated transmission oil - Change transmission oil
Damaged gears or improper backlash - Set backlash correctly or change the gears
Bent or worn shift forks - Shift forks need to be replaced
Transmission fluid leakage
Gaskets or seals are damaged - Install new components
Cracked transmission case - Install a new transmission case

Hydraulics Troubleshooting
Excessive hydraulic system heat
System pressure has not been adjusted correctly - Pressure needs to be adjust correctly
Main relief valve incorrect adjustment or failure - Replace or set up the relief valve
Hydraulic oil is contaminated - Fill up with fresh hydraulic oil
Air enters in hydraulic system - Check the pump seals, suction pipe, and fittings
Hydraulic fluid pressure is insufficient
Lack of hydraulic oil - Fill up the hydraulic oil
Dirty hydraulic oil filter - Replace hydraulic filter element or service if necessary
Hydraulic pump not working - Check pump performance and change it if necessary
Hydraulic control valve is faulty or out of adjustment - Adjust properly or replace
Hydraulic cylinder is broken - Inspect cylinder components for damage or wear and change if required
Hydraulic lines are leaking - Inspect hydraulic system for leaks and repair it
Hitch cannot be lifted or lifting is too slow
Not enough hydraulic oil in the system - Check oil level and add hydraulic oil as required
Cold fluid in hydraulic system - Wait for fluid to warm up
Hydraulic fluid filter element clogging - Change the hydraulic filter element or service if required
Damaged hydraulic oil pump - Flow-rate pump and change pump if necessary
Main relief valve malfunction or incorrect adjustment - Adjust or change relief valve
Damaged or incorrect adjusted hydraulic control valve - Adjust properly or change
Hydraulic cylinder is broken - Check cylinder components for wear or damage and change if necessary
Broken or loose suction line - Retighten or change
3-point hitch fails to drop or drops slowly
Faulty or incorrect setting hydraulic spool valve - Adjust correctly or change
Hydraulic cylinder is not working - Inspect cylinder components for wear or damage and change if required
Hitch cross shaft is worn - Install a new shaft
Mechanical parts of the hitch are damaged - Change defective or worn hitch parts
Hitch jerks when drop or lift
Air in hydraulic system - Inspect the pump seals, suction pipe, and fittings
Dirty hydraulic oil - The oil must be changed
Damaged hydraulic oil pump - Test pump flow rate and replace pump if required
Hydraulic control valve block is not set properly or defective - Adjust correctly or change
Hydraulic cylinder malfunction - Check the hydraulic cylinder parts for damage or wear and replace if necessary

Steering System Troubleshooting
Steering wheel is difficult to turn
Steering column is defective or improperly assembled - Change steering column or assemble properly
Aeration in steering system - Bleed air
Toe-in adjustment is incorrect - Check and adjust toe-in
Front tires are worn out - Install new tires
Steering pump is faulty - Repair or replace steering pump
Damaged or worn power steering valve - Inspect and change as required
Faulty steering box parts - Replace defective components of power steering box
Low steering oil level - Fill up the steering oil
Oil leaks in the steering system - Retighten steering hose and pipe connections
Excessive steering wheel play
Worn steering column shaft or coupling - Replace faulty component
Defective or worn power steering valve - Replace or repair steering valve as required
Faulty steering box components - Replace defective components of power steering box
Steering pump malfunction - Steering pump needs to be replaced or repaired
Steering linkage or tie-rod ends are defective - Change damaged component
Tractor pulls to right or left
Tires are not properly inflated - Inflate tires as required
Toe-in adjustment is incorrect - Adjust toe-in wheels properly
Faulty or worn steering tie-rod ends or linkage - Change failed part
Worn steering box parts - Replace defective parts of power steering box
Damaged or worn power steering valve - Repair or replace the steering valve
Incorrectly adjusted or worn front hub bearings - Adjust correctly or replace bearings




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