Engine

Engine hard to start, will not start.

Hydro linkage improperly adjusted.

Adjust hydro linkage.

Fuel tank empty.

Add fuel and bleed fuel system.

Water, dirt, or air in fuel system.

Drain, flush, fill, and bleed fuel system.

Safety switch not activated.

Move hydro lever to neutral. Inspect switch.

Low compression.

See your John Deere dealer.

Low battery output.

Check battery voltage. Clean battery. Charge if necessary.

Excessive resistance in starting circuit.

Clean and tighten all connections on battery and starter.

Crankcase oil of too heavy viscosity.

Drain and fill crankcase with John Deere TORQ-GARD SUPREME ® oil of proper viscosity and quality.

Improper type or old fuel.

Consult fuel chart and use proper type of fuel for operating conditions.

Sticking valves.

See your John Deere dealer.

Throttle linkage loose or not adjusted properly.

Check throttle linkage and adjust if necessary.

Fuel pump primer lever position.

Place lever in down position.

Solenoid disconnected.

Check wiring.

Dirty or faulty injectors.

See your John Deere dealer.

Faulty injection pump solenoid.

Replace solenoid.

Plugged fuel filter.

Replace filter element and bleed system.

TORQ-GARD SUPREME is a trademark of Deere & Company.

NXH8,M68440,L1 -19-15JUL98-1/7

Plugged fuel prefilter.

Replace prefilter element and bleed system.

Engine knocks.

Low coolant temperature.

Incorrect or defective thermostat.

Loose or failed main bearing or connecting rod bearing, worn pistons and cylinders.

See your John Deere dealer.

Insufficient oil.

Add oil of proper viscosity and quality.

Clogged air intake.

Clean air intake.

Injection pump out of time.

See your John Deere dealer.

Injection nozzle valve sticking.

See your John Deere dealer.

Air in fuel system.

Clean and bleed fuel system.

Engine runs irregularly or stalls frequently.

Low coolant temperature.

Run engine until sufficiently warm; also check thermostat.

Clogged fuel filter.

Replace filter element and bleed system.

Clogged prefilter

Replace prefilter and bleed system.

Prefilter installed backwards.

Install prefilter in correct position and bleed system.

Bent push rods or sticky valves.

See your John Deere dealer.

Water, dirt or air in fuel system.

Drain, flush, fill and bleed system. Tighten fuel connections.

Injection pump out of time.

See your John Deere dealer.

Injection pump speed advance.

See your John Deere dealer.

Dirty or faulty injectors.

See your John Deere dealer.

Solenoid wire loose.

Check wiring.

Low fuel level.

Add fuel and check system.

NXH8,M68440,L1 -19-15JUL98-2/7

Lack of power.

Engine overload.

Reduce load.

Intake air restrictions.

Clean air cleaner.

Improper thermostat.

Change to proper thermostat.

Improper valve clearance.

See your John Deere dealer.

Contamination in fuel tank.

Clean out fuel tank and replace fuel prefilter and filter.

High altitude operation.

Engine loses horsepower with increase in altitude. Use proper type of fuel for high altitude.

Unsatisfactory fuel.

Use fresh fuel of proper type.

Overheated engine.

Allow engine to cool.

Throttle position or speed adjustments.

Use proper throttle position and speed adjustment.

Clogged fuel filter.

Replace filter element and bleed system.

Clogged prefilter.

Replace prefilter and bleed system.

Prefilter installed backwards.

Install prefilter in correct position and bleed system.

Dirty or faulty injectors.

See your John Deere dealer.

Injection pump out of time.

See your John Deere dealer.

Automatic advance not working.

See your John Deere dealer.

Turbocharger not functioning.

See your John Deere dealer.

NXH8,M68440,L1 -19-15JUL98-3/7

Engine overheats.

Engine overloaded.

Reduce load.

Low coolant level.

Fill radiator with coolant to the proper level. Check hoses and radiator for leaks or loose connections.

Leaking head gasket.

See your John Deere dealer.

Engine timed too late.

See your John Deere dealer.

Engine side screens constantly plugged.

Install air intake stack and front screen attachment.

Dirty cooling system radiator core, air conditioning condenser or screens.

Remove all foreign matter from exterior or radiator core, air conditioning condenser and screens. Steam clean if necessary.

Defective thermostat, pressure cap, switch or gauge.

Remove and check.

Loose or defective fan belt.

Replace belt.

Wrong oil viscosity.

Change to proper oil viscosity.

Cooling system limed up.

Drain and flush cooling system.

Engine temperature below normal.

Defective thermostat, gauge or sender unit.

Remove and check.

Low oil pressure.

Low oil level.

Check crankcase oil level on dipstick and add oil if necessary.

Improper type of oil.

Drain and fill crankcase with John Deere TORQ-GARD SUPREME ® oil of proper viscosity and quality.

TORQ-GARD SUPREME is a trademark of Deere & Company.

NXH8,M68440,L1 -19-15JUL98-4/7

Engine uses too much oil.

Oil leaks or engine overheating.

Check for leaks in lines and around gaskets and drain plugs.

Too low viscosity crankcase oil.

Drain and fill crankcase with oil of proper viscosity and quality.

Excessive engine speed.

Check speed adjustment.

High oil pressure.

See your John Deere dealer.

Scored pistons, stuck rings or worn valve guides.

See your John Deere dealer.

Internal parts worn.

See your John Deere dealer.

Restricted air intake system.

Check air cleaner and swab out air intake.

Failed oil pump.

Replace oil pump.

Engine uses too much fuel.

Improper type of fuel.

Use proper type fuel for operating conditions.

Engine out of time.

See your John Deere dealer.

Clogged or dirty air cleaner.

Clean air cleaner.

Automatic advance not working.

See your John Deere dealer.

Dirty or faulty injectors.

See your John Deere dealer.

Engine overloaded.

Reduce load.

NXH8,M68440,L1 -19-15JUL98-5/7

Engine emits black or gray exhaust smoke.

Improper fuel type.

Use proper type of fuel for operating conditions.

Engine out of time.

Make sure injection pump is timed properly. (See your John Deere dealer).

Clogged or dirty air cleaner.

Check air cleaner for restrictions. Be sure filter element is clean.

Engine overloaded.

Reduce load.

Defective muffler.

Check the muffler for possible damage which might create back pressure. Clean muffler.

Dirty or faulty injectors.

See your John Deere dealer.

Automatic advance not working.

See your John Deere dealer.

Air in fuel system.

Bleed fuel system. Check all connections and fuel tank level.

Engine emits white exhaust smoke.

Cold engine.

Warm engine to normal operating temperatures.

Engine out of time.

Make sure injection pump is timed properly. (See your John Deere dealer).

Improper type of fuel.

Low octane fuel will cause misfiring. Use only fuel which has recommended cetane or octane number.

Thermostat defective or too cold.

Remove and check thermostat.

Battery will not charge.

Defective battery.

Check voltage and/or specific gravity and electrolyte level.

Loose alternator belt.

Replace belt.

Loose or corroded connections.

Clean and tighten battery connections.

Alternator not functioning properly.

See your John Deere dealer.

NXH8,M68440,L1 -19-15JUL98-6/7

Starter cranks slowly or will not crank.

Low battery output.

Use voltmeter to check state of charge.

Safety switch not activated.

Move hydro-drive lever to neutral.

Loose or corroded harness or battery connections.

Clean and tighten loose connections.

Starter solenoid defective.

Repair or replace, if necessary.

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