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Kubota D850 Troubleshooting

Engine Model: Kubota D850
Engine Type: 4-cycle 3-cylinder liquid-cooled diesel engine
Total Displacement: 52.2 (0.85 L)
Rated Engine Power: 19.8 Hp (14.9 kW) at 3200 rpm
Aspiration Type: Naturally aspirated


Engine hard to start or won't start

Dirty fuel filter - Clean the filter element.
There is air in the fuel system - Bleed the system.
Defective or clogged injection nozzle - Check and replace nozzles if required.
Damaged fuel injection pump - Install a new pump or rebuild.

Diesel starts but stalls suddenly

Fuel filter plugging - Clean or replace the filter.
Faulty fuel injection pump - Change pump or rebuild it.
Dirty air filter - Clean or change.

Engine stops running suddenly

Incorrect adjustment of fuel injection pump timing - Set the fuel pump timing correctly.
Clogged fuel filter - Filter maintenance required.
Engine is not preheated - Normalize the temperature by warming up the engine.

Engine stalls when idle

Too low idle RPM - Correct low idle adjustment.
Incorrect valve clearance - Need to adjust valve clearance.
Damaged fuel injection pump - Repair or install a new fuel pump.

Engine lacks power

Faulty or dirty injection nozzles - Replace injection nozzles.
Dirty fuel hoses or lines - Clean fuel system lines and hoses.
Plugged air filter - Clean or replace element.
Cylinder head gasket is damaged - Replace cylinder head gasket.

Engine overheated

Dirty radiator core or faulty radiator cap - Install new cap or clean radiator.
Insufficient coolant - Fill the cooling system and check components for leaks or other faults.
Loose or defective fan belt - If necessary, replace the belt.
Engine oil insufficient - Check and refill engine oil.

Oil pressure is low

Low oil level - Add oil as required.
Oil pump is worn or damaged - Check and replace if necessary.
Oil filter clogging - Clean or replace engine oil filter element.

High oil consumption

Oil leaks: Damaged seals or gaskets - Change to repair leaks.
Improper oil viscosity - Use correct viscosity oil.
Worn or stuck piston rings - Change the piston rings as required.
Valve guides and stems are worn - Valves need to be changed.
Scuffed cylinder liners or pistons - Check pistons and liners, install new parts as required.

Engine noise or knocking

Coolant temperature is low - Warm up the engine.
Engine oil level is low - Add oil to the engine crankcase.
Incorrect adjustment of fuel injection pump timing - Set up as recommended.
Pistons are worn or broken - Replace the pistons.
Connecting rod is worn or misaligned - Replace or align connecting rod.

Starter turns slow

Low battery voltage - Recharge the battery.
Battery will not hold charge - Service or change the battery.
Battery cables are disconnected or terminals are faulty - Check cables and service or change terminals.

Starter is not cranking

Battery is drained or worn - Replace or charge as required.
Wiring is improperly connected or disconnected - Check wiring and connect properly.
Low battery capacity - Battery needs to be recharged.
Faulty starter motor - Repair or install a new starter.