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Home / Farm Tractors / Kubota Tractors / Kubota B6100

Kubota B6100 Troubleshooting

The Kubota B6100 sub compact tractor was manufactured from 1978 to 1997. This model was designed in 4 versions: B6100E (2WD Gear), B6100D (4WD Gear), B6100HST-E (2WD Hydrostatic), and B6100HST-D (4WD Hydrostatic). The Kubota B6100 tractor is powered by 41.2 cubic inches (675 cc) Kubota D650-A 4-cycle vertical three-cylinder liquid-cooled diesel engine.

The engine has a cylinder bore of 2.52" (64 mm), piston stroke of 2.76" (70 mm), rated power of 14.3 hp (10.6 kW), and 36.5 Nm (27.1 lb-ft) of max torque at 1800 rpm. The Kubota B6100 is fitted with two transmission options: mechanical transmission with 6 forward and 2 reverse gears, or 2-range hydrostatic transmission with infinite forward and reverse gears. The maximum travel speed (forward and reverse): 9.1 mph (14.5 km/h) / 6.2 mph (10.1 km/h).

The Kubota B6100 is equipped with a manual steering system, mechanical shoe (Gear) or internal expanding (HST) brakes, 4.00x9 (2WD) or 6.00x12 (4WD) front tires, and 7.00x16 (2WD) or 8.00x16 (4WD) rear tires. The gear models have a wheelbase of 48.9" (1240 mm) with 2WD or 49.1" (1245 mm) with 4WD. The HST models have a wheelbase of 54.7" (1380 mm) with 2WD or 55.1" (1390 mm) with 4WD.

Engine Troubleshooting
Engine won't start or hard to start
Fuel filter is dirty - Replace filter element
Closed fuel cock - Open fuel on-off cock to inject fuel
Fuel lines leaking air - Tighten clamps, change faulty pipes
Fuel injectors are clogged or faulty - Test fuel injectors and change if necessary
Fuel injection pump failure - Repair or change injection pump
Bad engine compression - Check and change damaged parts
Diesel shuts off during operation
Engine has not warmed up to the recommended temperature - Warm up the engine
Water, dirt, or air in fuel system - Drain, flush, fill, and bleed system
Irregular fuel injection - Adjust fuel injection timing
Plugged fuel filter - Change the filter element
Clogged or damaged injectors - Clean or replace fuel injectors
Engine stops after starting
Incorrectly set fuel injection pump timing - Check and correct adjustments
Fuel filter is dirty - Replace the filter element
Fuel injector nozzles are dirty or defective - Change or clean injector nozzles
Faulty fuel injection pump - Repair or install a new fuel pump
Dirty air cleaner element - Install new cleaner element or replace it
Engine stalls when idle
Low idle speed setting is incorrect - Correct low idle settings
Fuel injection pump is broken - Install a new fuel pump or repair
Fuel injector nozzles fault - Service or replace injector nozzles
Incorrect valve clearance - Adjust valve clearance
Engine overheating
Lack of coolant in cooling system - Add the coolant. Inspect the system for leaks
Cooling system components are failed or system is clogged - Flush cooling system or change faulty components
Lack of engine oil - Fill the crankcase with engine oil
Damaged fan belt or incorrect belt tension - Adjust belt tension properly or change it
Thermostat fault - Check and change if necessary
Diesel engine is losing power
Fuel injectors are defective or dirty - Change fuel injectors
Incorrect fuel injection pressure - Adjust pressure to proper level
Dirty air filter element - Replace or clean the air filter element
Dirty oil filter element - Service or change engine oil filter element
Engine is overloaded - Load reducing is recommended
Valve clearance is not correct - Adjust valve clearance according to specifications
Low idle speed adjustment is incorrect - Normalize low idle speed
Dirty fuel pipes or hoses - Service fuel pipes and hoses
Insufficient engine compression: Valves are broken or leaking - Valves need to be replaced
Engine noises or knocks
Timing of fuel injection pump is wrong - Fuel pump timing settings need to be corrected
Fuel injector nozzles are defective or dirty - Install new set of properly balanced nozzles
Engine oil level is insufficient - Fill up the engine oil
Low coolant temperature - Warm up engine as required
Main bearings or crankshaft are worn out - Replace crankshaft or bearings
Stuck or worn piston rings - Replace the piston rings as required
Flywheel mounting screws are loose - Tighten the screws
Excessive engine oil consumption
Oil leaking: Defective seals or gaskets - Change to repair leaks
Incorrect oil viscosity - Use oil of correct viscosity
Worn or stuck piston rings - Change the piston rings as required
Worn valve stems and valve guides - Replace defective valves
Pistons or cylinder liners are scored - Inspect pistons and liners, fit new components as necessary

Electrical System Troubleshooting
Battery cannot be charged
Battery is worn - Change the battery
Damaged battery wiring harness - Inspect wiring for damage, replace or repair
Battery terminals and cables are corroded or loose - Tighten or clean terminals and cables
Damaged belt or incorrectly adjusted belt tension - Change belt or adjust belt tension properly
Starter turns slowly
Low battery power - Charge the battery
Battery is draining quickly - Service charging system or replace battery
Bad battery cable harness - Inspect cables for malfunctions, repair or change
Loose or corroded cables and terminals - Service or tighten battery cables and terminals
Starter motor is not working
Low battery output - Low battery charging, charge as required
Discharged or worn battery - Charge or change the battery
Defective starter motor - Repair or install a new starter
Incorrectly connected or disconnected wires - Check battery wires and connect correctly

Transmission Troubleshooting
Hard shifts
Incorrectly adjusted or damaged clutch - Clutch needs to be replaced or adjusted
Damaged or loose gear shift linkage - Service or replace shift linkage
Shift forks are worn or damaged - Change the shift forks
Faulty parts in the gear shifting mechanism - Change faulty parts
Lack of transmission oil pressure
Fluid level is low - Check transmission fluid level and add it as required
Dirty transmission oil filter (if fitted) - Change or service the transmission oil filter
Faulty relief valve - Replace relief valve
Transmission makes excessive noise
Cracked or worn bearings - Bearings replacement required
Not enough fluid in transmission - Add transmission fluid as required
Dirty transmission oil - Transmission oil must be changed
Defective gears or incorrect backlash - Set backlash properly or change the gears
Shift forks are worn or damaged - Replace defective shift forks
Transmission oil leakage
Broken gaskets or seals - Install new components
Cracked transmission housing - Housing needs to be replaced

Hydrostatic Transmission Troubleshooting
HST transmission is excessively noisy
Dirty transmission oil or insufficient oil level - Change the oil or fill to required level
Speed control rod linkage is damaged or unadjusted - Repair or adjust link rod linkage
Relief valve is defective - Replace the valve
Transmission overload - The load should be reduced
Transmission components are worn or damaged - After disassembly and checking, replace worn components
Transmission oil overheated
Not enough oil in transmission - Check transmission oil level and add oil as required
Clogged transmission fluid filter element - Change or clean the transmission fluid filter
Cooling components are plugged or defective - Check all cooling components and change or repair if required
Excessive transmission load - Reduce transmission load
Low power
Not enough oil in transmission - Checking transmission oil level and add if necessary
Low charge pressure - Test charge pressure
Relief valve is worn or defective - Replace relief valve as required
Transmission oil leakage
Gaskets or seals are damaged - Replace worn seal or gaskets
Internal transmission case pressure is too high - Replace defective components
Clogged transmission fluid drain line - Service or replace drain line

Hydraulics Troubleshooting
Hydraulic system overheating
Hydraulic system pressure is not adjusted correctly - Correct adjustment is required
Faulty or incorrectly adjusted main relief valve - Adjust or replace the relief valve
Hydraulic oil contamination - Change the oil
Air trapped in the hydraulic system - Check the pump seals, suction line, and fittings
Hydraulic fluid pressure is insufficient
Lack of hydraulic fluid - Need to add fluid
Hydraulic fluid filter element clogging - Replace filter element or clean if required
Damaged hydraulic oil pump - Flow-rate hydraulic pump and replace pump if necessary
Defective or incorrect setting hydraulic control valve block - Adjust properly or replace
Broken hydraulic cylinder - Inspect the hydraulic cylinder components for damage or wear and change if required
Hydraulic pipes are leaking - Inspect hydraulic system for leaks and repair it
Three-point hitch lifting is too slow or cannot be lifted
Lack of hydraulic fluid - Add fluid to the hydraulic system
Hydraulic oil is too cold - Allow oil to warm
Hydraulic oil filter is dirty - Service or replace the hydraulic filter
Hydraulic pump not working - Check hydraulic pump flow and replace pump if necessary
Main relief valve malfunction or incorrect adjustment - Adjust relief valve or change if required
Hydraulic control valve is defective or set improper - Replace or adjust correctly
Broken hydraulic cylinder - Inspect cylinder parts for wear or damage and replace if required
Damaged or disconnected suction pipe - Connect or replace
Hitch does not lower or lowers very slowly
Hydraulic spool valve block is faulty or out of adjustment - Replace or adjust correctly
Defective hydraulic cylinder - Check cylinder components for wear or damage and change if necessary
Damaged lift arm shaft - Replace the shaft
The hitch is defective if there is internal mechanical damage - Change worn or damaged hitch components
Hitch raises or lowers not smoothly
Air trapped in the hydraulic system - Check the pump seals, suction pipe, and fittings
Contaminated hydraulic fluid - Change hydraulic fluid
Hydraulic pump failure - Flow-rate hydraulic pump and replace pump if necessary
Hydraulic spool valve block is defective or set improper - Change or adjust correctly
Faulty hydraulic cylinder - Inspect cylinder parts for wear or damage and replace if required

Steering System Troubleshooting
Hard Steering
Steering knuckle or steering column is stuck - Inspect steering column and knuckle, replace worn parts
Steering gearbox components are worn - Replace defective components of steering gearbox
Faulty drag link or tie rod - Replace or repair
Insufficient lubrication in steering box - Need to lubricate the gearbox
Not adjusted toe-in alignment - Check and adjust toe-in
Tires are not correctly inflated - Inflate tires as necessary
Excessive steering wheel free play
Steering column bearing or shaft is worn - Change faulty parts
Steering linkage assembly is worn or loose - Repair or replace steering linkage
Worn steering gearbox bearings - Replace the bearings
Front wheel hub bearings or steering knuckles are worn - Change hub bearings or knuckles
Damaged or worn steering tie-rod ends - Change faulty part
Tractor pulls to right or left
Worn or loose steering linkage assembly - Repair or replace steering linkage
Defective steering knuckle bushing - Replace knuckle bushing
Uneven tire pressure - Inflate the tires properly
Toe-in adjustment is incorrect - Adjust toe-in correctly

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