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Kubota M6800 Troubleshooting

The Kubota M6800 is a 2-wheel drive or 4-wheel drive utility tractor from M-Series. This model was manufactured between 1997 and 2005. The Kubota M6800 driveline includes a V3300 four-cylinder water-cooled diesel engine and 8x8 synchronized shuttle transmission, or power shuttle transmission with 8 forward and 8 reverse gears.

A 3.3L (202 cu.in) engine power is 70.9 hp (52.9 kW) at 2600 rev/min. The maximum forward/reverse speed - 20.7 mph (33.3 km/h). The open center hydraulic system includes a gear pump with a rated fluid flow of 11 gpm (41.6 lpm).

The main relief pressure is 195 bar (2830 psi). The standard lift capacity is 4200 lbs (1905 kg). The 2WD models are equipped with 7.50x16 front tyres and 16.9-30 rear tyres. The 9.50x24 front tyres and 16.9-30 rear tyres fit 4WD tractors. The wheelbase is 80.7 in (2040 mm) for models without cab and 83.7 in (2120 mm) for models with cab. The Kubota M6800 is compatible with LA1002 front end loader with a maximum lift height of 115.6 in (2930 mm), and LA1162 front end loader with a maximum lift height of 114 in (2890 mm).

Engine Troubleshooting
Engine doesn't start or hard to start
Fuel filter plugging - Replace the 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 defective or dirty - Service or change fuel injectors
Fuel injection pump malfunction - Repair or install new pump
Bad engine compression - Inspect cylinder block and replace worn components
Engine stalls during operation
Engine not warmed up - Warm up to required temperature
Air in fuel lines - Bleed fuel lines
Uneven fuel injections - Repair or adjustment
Plugged fuel filter - Clean the filter element
Faulty or dirty injectors - Change fuel injectors
Engine starts and then stalls
Fuel injection pump out of timing - Adjust injection timing
Fuel filter is dirty - Change the filter element
Fuel injector nozzles are dirty or defective - Inspect injector nozzles and change if required
Fuel injection pump is broken - Rebuild or change fuel pump
Clogged air cleaner - Replace cleaner or install new cleaner element
Engine stalls when idling
Too low idle RPM - Normalize low idle speed
Damaged fuel injection pump - Rebuild or replace pump
Clogged or defective injector nozzles - Check and change nozzles as required
Valve clearance is not correct - Adjustment procedure required
Engine is overheated
Engine has a lack of coolant - Top up coolant. Check and repair damage to the cooling system if required
Cooling system is clogged or cooling parts are defective - Replace faulty parts or service cooling system
Not enough engine oil - Need to add engine oil
Fan belt is worn or belt tension is improper - Adjust belt tension properly or change it
Thermostat fault - Check and replace if required
Engine power is insufficient
Dirty or faulty injectors - Clean or replace fuel injectors
Insufficient fuel injection pressure - Adjust pressure to proper level
Air filter is dirty - Replace or clean the air filter element
Oil filter clogging - Clean or change engine oil filter
Engine is running overloaded - Load reducing required
Incorrect valve clearance - Check and adjust
Incorrectly adjusted low idle speed - Correct the settings
Fuel hoses or pipes clogging - Service fuel pipes and hoses
Engine compression too low: Valves are broken or leaking - Replace the valves
Engine knocking sound or abnormal noise
Incorrectly set fuel injection pump timing - Check and correct settings
Fuel injector nozzles are faulty - Change injector nozzles
Engine oil insufficient - Check oil level and add oil as required
Engine is not preheated - Warm up the engine
Main bearings or crankshaft wear - Crankshaft or bearings need to be replaced
Piston rings failure - Have piston rings replaced
Flywheel mounting screws are loose - Tighten the screws
Engine consuming too much oil
External oil leaks: Worn seals or gaskets - New components need to be installed
Oil viscosity is incorrect - Use oil of correct viscosity
Piston rings are stuck or worn - Have piston rings replaced
Worn valve stems and valve guides - Install new valves
Scored cylinder liners or pistons - Check pistons and liners, change as required

Electrical System Troubleshooting
Battery won’t charge
Battery bad cell - Replace the battery
Battery wiring harness damage - Inspect battery wiring for damage, replace or repair
Corroded or loose cables and terminals - Tighten or service terminals and cables
Defective belt or improperly adjusted belt tension - Adjust belt tension correctly or replace belt
Starter cranks slowly
Low battery output voltage - Battery is drained, charge it
Battery won’t hold charge - Battery needs service or replacement
Damaged battery electrical wire harness - Inspect electrical wires for damage, change or repair
Loose or corroded cables and terminals - Service or tighten battery terminals and cables
Starter doesn't crank
Battery power is low - Charge the battery
Discharged or worn battery - Need to charge or replace the battery
Starter motor failure - Starter needs to be replaced
Improperly connected or disconnected wiring harness - Inspect wiring harness and connect properly

Transmission Troubleshooting
Hard shifting
Failure or improper clutch adjustment - Adjust clutch or change if necessary
Stuck or damaged gear shift linkage - Repair or change shift linkage
Damaged or worn shift forks - Shift forks need to be replaced
Faulty gear shifting mechanism - Faulty parts must be changed
Transmission oil pressure is insufficient
Oil level is low - Correct the transmission oil level
Clogged transmission fluid filter element (if fitted) - Clean or replace the transmission fluid filter
Relief valve failure - Install a new relief valve
Excessive transmission noise
Bearings are worn or cracked - Install new bearings
Fluid level is low - Fill system with correct transmission fluid level
Dirty transmission oil - Change transmission oil
Damaged gears or improper backlash - Set backlash correctly or change the gears
Worn or damaged shift forks - Replace defective shift forks
External fluid leaks
Gaskets or seals are defective Replace worn seal or gaskets
Transmission housing is cracked - Replace housing or transmission assembly

Hydraulics Troubleshooting
Hydraulic system is too hot
Hydraulic system pressure is unadjusted - Adjust the pressure as required
Defective or misadjusted main relief valve - Replace or set up the relief valve
Contaminated hydraulic fluid - Change hydraulic fluid
Air leaks in hydraulic system - Inspect the suction pipe, fittings, and pump seals
Low hydraulic fluid pressure
Lack of hydraulic oil - Fill up the hydraulic oil
Hydraulic fluid filter clogging - Clean or change hydraulic filter
Hydraulic pump is defective - Flow-rate pump and change pump if necessary
Hydraulic control valve block is faulty or out of adjustment - Replace or set correctly
Hydraulic cylinder failure - Check the hydraulic cylinder parts for damage or wear and replace if necessary
Leakage in hydraulic pipes - Find leaks in hydraulic system and repair it
3-point hitch does not raise or raises very slowly
Lack of hydraulic oil - Add oil to the hydraulic system
Cold oil in hydraulic system - Wait for oil to warm up
Hydraulic oil filter clogging - Install a new hydraulic filter element
Hydraulic pump is faulty - Test the pump performance and change pump if required
Unadjusted or defective main relief valve - Adjust or replace the relief valve
Defective or not adjusted hydraulic control valve - Adjust properly or change
Hydraulic cylinder is not working - Check cylinder components for wear or damage and change if necessary
Damaged or loose hydraulic suction line - Tighten or change it
Hitch won't lower or lowers slowly
Defective or not adjusted hydraulic control valve - Replace or set properly
Faulty hydraulic cylinder - Inspect the hydraulic cylinder components for damage or wear and change if required
Damaged lift arm shaft - Replace the shaft
The hitch has mechanical faults - Replace worn or defective hitch components
Three-point hitch raises or lowers not smoothly
Air trapped in the hydraulic system - Inspect the suction pipe, fittings, and pump seals
Hydraulic fluid is dirty - Hydraulic fluid change required
Damaged hydraulic oil pump - Test pump performance and replace pump if necessary
Defective or not adjusted hydraulic spool valve - Set properly or replace
Hydraulic cylinder is defective - Check cylinder components for damage or wear and change if necessary

Steering System Troubleshooting
Steering wheel is hard to turn
Steering column is broken or incorrectly fitted - Steering column needs to be refit correctly or replaced
Air leaks in steering system - Air-bleed steering system
Improper toe-in adjustment - Adjust toe-in correctly
Tires are incorrectly inflated - Inflate as required
Steering pump not working - Check the steering pump and replace if necessary
Worn or damaged hydrostatic steering unit - Inspect and replace as required
Relief valve is stuck or defective - Inspect relief valve and replace if necessary
Lack of steering fluid - Need to add steering oil
Steering system oil leak - Tighten connections of hydraulic hoses and pipes in steering system
Excessive steering wheel free play
Steering column coupling or shaft is worn - Replace faulty component
Worn or defective hydrostatic steering unit - Inspect and change as required
Hydraulic steering pump is defective - Check the steering pump and replace if necessary
Steering tie-rod ends or linkage are worn - Change failed component
Tractor pulls to left or right
Low tire pressure - Inflate the tires
Not adjusted toe-in - Adjust toe-in properly
Steering tie-rod ends or linkage are worn - Change failed part
Worn or defective hydrostatic steering unit - Replace or repair steering unit as required
Steering cylinder is damaged - Repair or replace steering cylinder
Incorrectly adjusted or worn front hub bearings - Change or adjust bearings correctly



Farm Tractors Technical Specifications
JD 1026R JD 3650 JD 6400 JD 7810
FORD 1320 FORD 2810 FORD 3930 FORD 5600
MF 250 MF 690 MF 3060 MF 6180
NH TC48DA NH M100 NH T7550 NH 8560
CASE IH 495 CASE IH 1255XL CASE IH 2140 CASE IH 2294