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Kubota G26 Troubleshooting

The Kubota G26 is a 4WD diesel lawn tractor with heavy duty front axle. This model was manufactured from 2009 to 2015. The Kubota G26 driveline consists of a 61.1 cu.in (1L) Kubota D1005 4-cycle vertical 3-cylinder naturally aspirated water-cooled diesel engine with a rated power of 24.5 hp (18.5 kW), and hydrostatic transmission with infinite forward and reverse gears.

Max. forward speed - 10.6 mph (17 kph), maximum reverse speed - 6.3 mph (10 kph). The Kubota G26 is equipped with a full hydrostatic power steering, wet-type PTO clutch, wet disc brakes, 16x7.50-8 front tires, and 24x12.00-12 rear tires.

The wheel base is 57.7" (1460 mm). The diesel lawn tractor is compatible with a 54" mid-mount 2-blade rear discharge Kubota RCK54 mower deck with cutting height of 1.0-4.0" (25-102 mm), lifting height of 5.93" (150 mm), and hydraulic lift system.

Diesel Engine Troubleshooting
Engine is not starting or hard starting
Clogged fuel filter element - Clean the filter element
The fuel shut-off valve is closed - Open fuel shut-off valve
Fuel-line is leaking air - Retighten clamps, replace defective pipes
Dirty or faulty injectors - Service or change fuel injectors
Fuel injection pump damage - Replace or rebuild injection pump
Engine has bad compression - Check cylinder block and change faulty parts
Engine stalls during operation
Coolant temperature is low - Warm up the engine
Air in fuel system - Air-bleed fuel system
Irregular fuel injection - Adjust fuel injection timing
Fuel filter is dirty - Service or replace the filter
Dirty or faulty injectors - Service or change fuel injectors
Diesel engine stops after starting
Fuel injection pump out of timing - Correct injection timing
Plugged fuel filter - Replace filter element
Dirty or defective injector nozzles - Replace fuel injector nozzles
Fuel injection pump is not working correctly - Rebuild or replace pump
Dirty air cleaner element - Change or service air cleaner element
Engine stalls at idle
Wrong adjustment of low idle speed - Correct low idle settings
Damaged fuel injection pump - Repair or install new pump
Fuel injector nozzles are faulty - Service or replace injector nozzles
Excessive valve clearance - Adjust to proper valve clearance
Engine overheats
Lack of engine coolant - Top up coolant. Check system for leaks
Cooling system components are damaged or system is dirty - Service the cooling system or change faulty parts
Lack of engine oil - Fill up the engine oil
Fan belt tension is unadjusted or belt is worn - Adjust belt tension properly or change it
Thermostat malfunction - Check thermostat, replace if necessary
Loss of engine power
Clogged or damaged injectors - Service or change fuel injectors
Fuel injection pressure is wrong - Test fuel injection pressure and adjust it correctly
Dirty air filter element - Service or replace the air filter
Dirty oil filter - Service or change engine oil filter element
Engine is under excessive load - Change to lower gear or reduce load
Valve clearance is not correct - Adjust valve clearance
Too low idle RPM - Adjust the low idle speed
Dirty fuel hoses or pipes - Clean fuel pipes and hoses
Low engine compression: Valves are damaged or leaking - Change the valves
Engine knocks or noises
Incorrect setting of fuel injection pump timing - Correct injection timing
Clogged or damaged injector nozzles - Replace fuel injector nozzles
Engine oil level is insufficient - Fill up the oil to required level
Low coolant temperature - Warm up the engine
Main bearings or crankshaft failure - Have bearings or crankshaft replaced
Piston rings are defective or broken - Replace the piston rings as required
Loose flywheel bolts - Check flywheel bolts and tighten properly
Engine using too much oil
Oil leakage: Worn seals or gaskets - Worn parts need to be replaced
Oil viscosity is wrong - Use oil of correct viscosity
Damaged or seized piston rings - Piston rings need to be replaced
Worn valve guides and valve stems - Valves must be replaced
Pistons or cylinder liners are damaged - Check pistons and liners, change as required

Hydrostatic Transmission Troubleshooting
HST transmission noise
Worn or unadjusted speed control linkage - Adjust or repair linkage
Excessive transmission load - Reduce the load is required
Low transmission oil level or contaminated oil - Change transmission oil or top up to proper level
Transmission components are damaged or worn - Replace or repair defective components
Shifting is hard
Shift linkage is loose or broken - Service or change the linkage
Stuck or defective hydrostatic pump - Repair or change pump
Damaged or unadjusted transmission shift control components - Replace or adjust as required
Power is too low
Lack of transmission oil supply - Need to add transmission oil
Drive sheave is damaged or worn - Change sheave
Shifter linkage is not adjusted or faulty - Adjust correctly or change linkage
Speed control linkage is defective or unadjusted - Adjust or change linkage
Transmission leaking
Transmission gaskets or seals are worn - Replace gaskets or seals
Final drive shaft leakage - Replace shaft seals
Transmission housing is cracked - Housing needs to be replaced

Mower Deck Troubleshooting
Excessive mower vibration
Mower deck drive sheave is clogged or worn - Service or change sheave
Defective or loose drive belt - Adjust belt tension or change the belt
Warped or not balanced mower blades - Replace or balance blades
Loose blade bolts tightening - Tighten it fast
Discharge chute keeps clogging
Ground speed is too fast - Use a slower speed
Grass is too high - Adjust mower to lower cutting height
Reduced engine speeds - Throttle is not fully open
Mower deck set to low cutting - Use correct cutting height
Incorrect mower drive belt installation - Check drive belt for correct installation
Lawn mower leaving uncut grass
Cutting deck clogging - Mower deck needs to be cleaned
Blades are not sharp - Sharpen the blades
Worn or damaged blades - Blades need to be replaced
Mowing speed is too high - Use a lower speed
Cutting level is too low - Need to set high cutting height
Grass bag is full - Empty the grass bag
Blades are scalping the grass
Bumpy or not smooth lawn - Roll or level the lawn
Mower cuts too low - Must be set to high cutting height
High ground speed - Operate at slower speed
Improper mower deck level - Adjust mower deck level properly
Blades are bent or worn - Change the blades
Tires are not correctly inflated - Correct tire pressure
Mower cuts uneven
Tires are not correctly inflated - Need to inflate tires
Mower deck is not leveled properly - Level the deck properly
Blades are not sharp - Sharpen the blades
Worn or bent blades - Blades must be changed
Mower deck is clogged - Clean mower deck as required
Deck housing is broken - Repair or change the deck
Loose or faulty mower spindle - Repair or replace the spindle

Electrical Troubleshooting
Battery won’t charge
Loose or corroded cable connections - Tighten or clean connections
Defective battery terminal clamps - Replace terminal clamps
Bad cell in battery - Battery change required
Starter turns slowly
Low battery capacity - Battery needs to be recharged
Battery is draining quickly - Service or replace the battery
Corroded battery terminals or disconnected wires - Check cables and clean or change terminals
Starter is not cranking
Battery is discharged or worn - Recharge or change battery
Wiring harness is disconnected or improperly connected - Check wiring harness and connect as required
Low battery voltage - Battery needs to be recharged
Spark plug gapped improperly or faulty - Replace or clean and gap
Starter motor or solenoid failing - Change solenoid or repair starter



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