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Kubota B7100 Troubleshooting

The Kubota B7100 compact utility tractor was manufactured from 1976 to 1985. The tractor was designed in 2 versions: B7100E (2WD) and B7100D (4WD). The Kubota B7100 tractor is equipped with a 46.5 cu.in (0.8L) Kubota D750 4-cycle vertical 3-cylinder water-cooled diesel engine.

The engine has a cylinder bore of 2.68" (68 mm), piston stroke of 2.76" (70 mm), maximum power of 16 hp (11.9 kW), and 50.1 Nm (37.2 lb-ft) of peak torque at 1800 rpm. The mechanical transmission consists of a dry clutch and unsynchronized gearbox with 6 forward and 2 reverse gears.

The maximum travel speed (forward and reverse): 8.3 mph (13.4 km/h) / 4.2 mph (6.7 km/h). The open center hydraulic system includes a gear pump with fluid flow rate of 3 gpm (11.4 lpm). The hydraulic system pressure is 117 bar (1700 psi). The Kubota B7100 is equipped with a ball screw type manual steering, independent brakes with dry drum, 4.00x9 (2WD) or 6.00x12 (4WD) front tires, and 7.00x16 (2WD) or 8.00x16 (4WD) rear tires. The wheelbase is 48.8" (1240 mm) for 2-wheel drive models and 49.2" (1250 mm) for 4-wheel drive models.

Engine Troubleshooting
Engine doesn't start or hard to start
Fuel filter is clogged - Service or replace the filter
No fuel supply from the tank - Open the fuel supply valve
Air in fuel system - Air-bleed fuel system
Clogged fuel injectors - Clean or replace fuel injectors
Fuel injection pump is not operating properly - Install a new pump or rebuild
Bad engine compression - Inspect cylinder block and change damaged parts
Engine stops unexpectedly while running
Low coolant temperature - Engine is not warmed up to the required temperature
Water, dirt, or air in fuel system - Drain, flush, fill, and bleed system
Irregular fuel injection - Adjust fuel injection timing
Clogged fuel filter element - Replace filter element
Faulty or dirty injectors - Inspect fuel injectors and replace if necessary
Diesel engine stops after starting
Timing of fuel injection pump is not adjusted - Correct injection timing
Fuel filter is clogged - Change filter element
Faulty fuel injector nozzles - Check and change nozzles as required
Defective fuel injection pump - Replace injection pump or repair it
Air cleaner is clogged - Install new cleaner element or replace it
Engine stops while idle
Low idle speed setting is incorrect - Normalize low idle speed
Defective fuel injection pump - Install a new pump or rebuild
Fuel injector nozzles are defective or dirty - Replace fuel injector nozzles
The valve clearance is incorrect - Have it adjusted
Engine overheats
Lack of engine coolant - Fill cooling system to proper level. Check for coolant leaks
Cooling system parts are defective or system is dirty - Change faulty components or service cooling system
Engine oil insufficient - Check and refill engine oil
Fan belt is broken or belt tension is unadjusted - Adjust properly or replace the belt
Thermostat is defective - Test thermostat opening temperature, replace as required
Engine power is insufficient
Fuel injectors are damaged or dirty - Test fuel injectors and change if necessary
Incorrect fuel injection pressure - Test fuel injection pressure and adjust it correctly
Dirty air filter - Service or change air filter
Dirty oil filter - Change or service engine oil filter
Engine overloaded - Load reducing required
Excessive valve clearance - Adjust valve clearance
Incorrectly set low idle speed - Adjust as required
Fuel hoses or pipes are clogged - Fuel pipes and hoses need to be cleaned
Loss of compression: Valves are damaged or leaking - Valve replacement required
Engine knocking or noise
Timing of fuel injection pump is wrong - Check and correct adjustments
Clogged or damaged injector nozzles - Inspect injector nozzles and change if required
Engine oil insufficient - Fill up the oil to required level
Engine is not warmed up to the required temperature - Warm up the engine as required
Crankshaft or main bearings wear - Change or repair worn components
Piston rings failure - Have piston rings replaced
Loose flywheel bolts - Check flywheel bolts and tighten properly
Engine oil consumption is too high
External oil leaks: Gaskets or seals are excessively worn - Replace worn parts to avoid leaks
Improper oil viscosity - Fill up with the correct oil viscosity
Worn or broken piston rings - Change piston rings
Valve guides and stems are worn - Install new valves
Scuffed cylinder liners or pistons - Check pistons and liners, install new parts as required

Electrical System Troubleshooting
Battery will not charge
Worn-out battery - Replace the battery
Bad battery cable harness - Inspect cables for malfunctions, repair or change
Battery cables and terminals are loose or corroded - Service or tighten battery terminals and cables
Belt slipping or wrong belt tension adjustment - Install new belt or adjust belt tension as required
Starter motor cranks slow
Battery power is low - Battery is drained, charge it
Battery is not holding charge - Service battery or replace it
Battery wiring harness damage - Inspect battery wiring for damage, replace or repair
Corroded or loose battery terminals and cables - Tighten or service cables and terminals
Starter is not cranking
Low battery capacity - Low battery charging, charge as required
Drained or worn battery - Battery needs to be recharged or replaced
Faulty starter motor - Change or repair starter
Battery cables are disconnected or incorrectly connected - Check cables and reconnect it correctly

Transmission Troubleshooting
Gear hard to shift
Clutch is not adjusted or faulty - Adjust correctly or replace
Gear shift linkage is loose or broken - Service or replace shift linkage
Bent or worn shift forks - Replace defective shift forks
Defective gearshift mechanism - Replace defective components
Low transmission oil pressure
Insufficient fluid supply - Fill system with correct transmission fluid level
Clogged transmission fluid filter element (if fitted) - Change or service the transmission fluid filter
Relief valve is faulty - Replace the valve
Transmission noises
Bearings are worn or cracked - Faulty bearings should be changed
Insufficient oil supply - Checking transmission oil level and add if necessary
Dirty transmission oil - Transmission oil must be changed
Improper backlash or damaged gears - Set backlash properly or change the gears
Bent or worn shift forks - Shift forks need to be replaced
Transmission fluid leakage
Gaskets or seals are damaged - Change defective seal or gaskets
Transmission case is cracked - Replace case or transmission assembly

Hydraulics Troubleshooting
Hydraulic system is overheated
Hydraulic system pressure is unadjusted - Adjust the pressure as required
Main relief valve failure or incorrect setting - Adjust relief valve or change if required
Hydraulic fluid is dirty - Hydraulic fluid change required
Aeration in hydraulic system - Check the pump seals, suction pipe, and fittings
Hydraulic oil pressure too low
Lack of hydraulic oil - Add oil to the hydraulic system
Hydraulic fluid filter is clogged - Service the hydraulic filter or change if required
Hydraulic pump malfunction - Check pump flow and change pump if necessary
Hydraulic control valve is defective or set improper - Change or adjust properly
Hydraulic cylinder is defective - Check cylinder components for damage or wear and change if necessary
Leakage in hydraulic lines - Find leaks in the system and fix it
Hitch cannot be lifted or lifting is too slow
Lack of hydraulic fluid - Check and refill the hydraulic fluid
Cold hydraulic fluid - Warm up the fluid
Hydraulic oil filter clogging - Clean the hydraulic filter element or replace if necessary
Defective hydraulic pump - Test the pump performance and change pump if required
Main relief valve is defective or unadjusted - Adjust relief valve or change if required
Hydraulic control valve block is defective or set improper - Adjust properly or replace
Hydraulic cylinder malfunction - Check the hydraulic cylinder parts for damage or wear and replace if necessary
Broken or loose suction line - Retighten or change
3-point hitch drops slowly or won't drop
Hydraulic spool valve block is not set properly or defective - Replace or set properly
Hydraulic cylinder is defective - Inspect the hydraulic cylinder parts for damage or wear and replace if required
Worn hitch cross shaft - Install a new shaft
The hitch has internal mechanical malfunctions - Replace damaged or worn hitch parts
3-point hitch lift or lower is jerky
Aeration in hydraulic system - Inspect the pump seals, suction line, and fittings
Hydraulic fluid is dirty - Hydraulic fluid change required
Hydraulic pump malfunction - Test the pump performance and change pump if required
Faulty or incorrect setting hydraulic spool valve - Adjust properly or change
Defective hydraulic cylinder - Check the hydraulic cylinder parts for damage or wear and replace if necessary

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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MF 250 MF 690 MF 3060 MF 6180
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