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Kubota G23 Troubleshooting

The Kubota G23 is a 4-wheel drive diesel lawn tractor. This model was manufactured between 2009 and 2015. The components of Kubota G23 driveline system: Kubota D902 4-cycle vertical 3-cylinder naturally aspirated water-cooled diesel engine and hydrostatic transmission with infinite forward and reverse gears.

A 54.8 cubic inches (0.9L) engine has a cylinder bore of 2.83" (72 mm), piston stroke of 2.90" (73.6 mm), and rated power of 23.5 hp (17.5 kW). Max forward speed - 9.7 mph (15.5 km/h), max reverse speed - 5 mph (8 km/h).

The Kubota G23 is equipped with a hydrostatic power steering, wet disc brakes, 16x7.50-8 front tires, and 24x12.00-12 rear tires. The wheel base is 54.9" (1390 mm). The tractor is compatible with a 48" mid-mount 2-blade rear discharge Kubota RCK48 mower deck with cutting height of 1.0-4.0" (25-102 mm), dial cutting height adjustment, and hydraulic lift system.

Diesel Engine Troubleshooting
Engine hard starting or not starting
Fuel filter is dirty - Replace the filter element
No fuel supply from the tank - Open the fuel supply valve
Air in fuel pipes - Bleed fuel pipes
Clogged or damaged injectors - Clean or replace fuel injectors
Fuel injection pump failure - Change pump or rebuild it
Bad cylinder compression - Check and replace worn parts
Diesel shuts off during operation
Engine is not preheated - Warm up the engine as required
Fuel-line is leaking air - Retighten clamps, replace defective pipes
Improper fuel injection - Fuel injection settings required
Plugged fuel filter - Change the filter element
Clogged fuel injectors - Check fuel injectors and replace if required
Engine starts and immediately stalls
Timing of fuel injection pump is not adjusted - Repair or replace fuel injection pump
Plugged fuel filter - Replace the filter element
Dirty or defective injector nozzles - Service or replace nozzles if required
Fuel injection pump is not operating properly - Rebuild or replace pump
Dirty air cleaner - Replace or clean the air cleaner element
Engine stops while idling
Incorrect low idle setting - Adjust the low idle speed
Fuel injection pump is not working correctly - Repair or install a new fuel pump
Faulty fuel injector nozzles - Replace fuel injector nozzles
Excessive valve clearance - Adjust valve clearance according to specifications
Engine is overheated
Insufficient coolant fluid - Fill the radiator to the required level. Check for coolant leaks
Cooling system components are damaged or system is dirty - Change faulty components or flush cooling system
Not enough engine oil - Fill up the engine oil
Worn fan belt or incorrect belt tension - Adjust as required or replace belt
Thermostat fault - Test thermostat opening temperature, replace as required
Loss of engine power
Clogged fuel injectors - Check fuel injectors and replace if required
Improper fuel injection pressure - Adjust to proper pressure
Air filter is clogged - Service or change air filter
Oil filter is clogged - Replace or clean engine oil filter element
Engine is overloaded - Load reducing is recommended
The valve clearance is incorrect - Correct valve clearance
Too low idle RPM - Normalize low idle speed
Dirt in the hoses or pipes - Service fuel pipes and hoses
Engine low compression: Valves are broken or leaking - Have valves replaced
Engine knocking sound or abnormal noise
Incorrectly set fuel injection pump timing - Check and correct settings
Damaged or clogged injector nozzles - Service or replace nozzles if required
Engine oil level low - Fill up the oil to required level
Engine is cold - Warm up the engine
Main bearings or crankshaft are worn out - Change or repair worn components
Piston rings are damaged or broken - Piston rings need to be replaced
Loose flywheel bolts - Inspect flywheel bolts and tighten properly
High engine oil consumption
Oil leaks: Worn seals or gaskets - New components need to be installed
Crankcase oil too light - Fill up with the proper oil viscosity
Worn or broken piston rings - Piston rings need to be replaced
Damaged valve guides or valve stems - Need to replace the valves
Pistons or cylinder liners are scuffed - Inspect liners and pistons, fit new parts as necessary

Hydrostatic Transmission Troubleshooting
HST transmission is making noise
Defective or not adjusted speed control pedal linkage - Repair or adjust linkage
Transmission overloaded - Reduce transmission load
Contaminated transmission fluid or low fluid level - Pour fresh fluid or add transmission fluid to proper level
Damaged or worn components of transmission - Check internal transmission parts and replace if required
Difficult to shift
Worn or rusty shift linkage - Install new linkage
Worn or seized hydrostatic pump - Repair or replace pump
Transmission shift control components are defective or misadjusted - Change or adjust correctly
Power is too low
Transmission oil insufficient - Need to add transmission oil
Worn or damaged drive sheave - Change sheave
Shifting linkage is broken or misadjusted - Change or adjust linkage
Defective or not adjusted speed control pedal linkage - Replace or adjust linkage
Transmission leaks
Worn transmission seals or gaskets - Replace gaskets or seals
Final drive shaft leaks - Change shaft seals
Cracked transmission case - Replace defective case or transmission assembly

Mower Deck Troubleshooting
Excessive mower vibration
Dirty or worn mower drive sheave - Change or clean sheave
Loose or damaged drive belt - Adjust belt tension or change the belt
Cutting blades are bent or unbalanced - Replace or balance blades
Blade mounting bolts are loose - Bolts should be tightened
Discharge chute is constantly plugged
Ground speed is too fast - Use a lower speed
Grass is too long - Need to set low cutting height
Engine rpm is too low - Adjust choke to full opening
Cutting level is too low - Adjust mower to higher cutting height
Mower drive belt installation is improper - Check drive belt for correct installation
Patches of grass uncut
Cutting deck clogging - Clean out the mower deck
Blades are too dull - Blades need to be sharpened
Worn or defective blades - Blades need to be replaced
Fast mowing speed - Use a lower speed
Cutting level is too low - Use a higher cutting height
Filled bagger - Clean bagger
Blades scalp the grass
Lawn is uneven or bumpy - Level the lawn
Cutting level is too low - Raise the cutting height
Mowing speed is too high - Select a slower speed
Mower deck is not leveled properly - Deck should be adjusted correctly
Damaged or bent blades - Replace the blades
Tires are not correctly inflated - Inflate tires correctly
Mower deck to cut unevenly
Tires are not correctly inflated - Correct tire pressure
Incorrectly leveled mower deck - Level the deck properly
Excessive blade dullness - Need to sharpen the blades
Worn or bent blades - Change the blades
Clogged mower deck - Mower deck needs to be cleaned
Broken mower deck shell - Rebuild or replace mower deck
Loose or faulty mower spindle - Install new spindle or repair it

Electrical Troubleshooting
Battery will not charge
Corroded or loose cable connections - Clean or tighten wiring connections
Battery terminal connectors are faulty - Install new terminal connectors
Battery faulty cell - Battery change required
Starter turns slowly
Battery capacity is low - Charge the battery
Battery discharges quickly - Battery needs service or replacement
Battery cables are disconnected or terminals are faulty - Check wire connections and change or service terminals
Starter is not cranking
Battery is drained or worn - Charge or change the battery
Wiring is improperly connected or disconnected - Check wiring and connect properly
Low battery voltage - Charge the battery
Faulty or incorrectly gapped spark plug - Clean, gap or change spark plug
Damaged starter motor or solenoid - Repair starter or replace solenoid



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