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Home / Wheel Loaders / Caterpillar Wheel Loaders / Cat 906H

Caterpillar 906H Troubleshooting

The Cat 906H compact wheel loader is powered by 201 cu.in (3.3L) Caterpillar C3.4 vertical four-cylinder liquid-cooled diesel engine with a rated power of 70 hp (52 kW) at 2500 rpm. The Caterpillar 906H is equipped with a hydrostatic transmission, power steering system, hydraulic dry disc brakes, and 405/70R18 standard tires. The hydraulic system has a pump with fluid flow rate of 22 gpm (83 lpm). The hydraulic pressure is 3400 psi (235 bar). The wheel loader has a rated operating capacity of 3483 lbs (1580 kg) and tipping load of 6967 lbs (3160 kg). The maximum lift height is 127.1" (3230 mm) to hinge pin, and bucket breakout force is 9440 lbs (4290 kg).

Engine Troubleshooting

Engine starts up hard or won't start
There is air in the fuel system - Bleed the system.
Fuel filter plugging - Clean or replace the filter.
Clogged or defective injection nozzles - Change fuel injection nozzles.
Water in the fuel system - Change fuel and repair fuel system.
Valve clearance is wrong - Adjust to proper valve clearance.
Fuel injection pump is broken - Rebuild or install a new injection pump.

Diesel starts but stalls suddenly
Air cleaner is clogged - Service or replace air cleaner.
Fuel filter element is clogged - Clean the filter or install new filter element.
Fuel injection pump has loose connections - Tighten the connections.
Dirty or defective injectors - Test and replace fuel injectors if necessary.
Fuel injection pump is faulty - Repair or change injection pump.

Engine stalls while running
Coolant temperature is low - Warm up to required temperature.
Fuel filter element clogging - Clean or replace the filter.
Air in fuel tank - Bleed fuel tank.
Clogged or defective injection nozzles - Replace injection nozzles.
Improper setting of fuel injection pump timing - Set it up as required.

Engine stalls when idle
Improperly adjusted low idle speed - Correct low idle adjustment.
Fuel injection pump is faulty - Repair or install new pump.
Fuel injector fault - Test and replace fuel injectors if necessary.
Valve clearance is out of adjustment - Need to adjust valve clearance.

Diesel engine loses power
Clogged air cleaner - Service or replace air cleaner.
Faulty or dirty injection nozzles - Check and replace nozzles if required.
Incorrect fuel injection pressure - Test fuel injection pressure and adjust it correctly.
Improper valve clearance - Have it adjusted.
Incorrect low idle setting - Adjust the low idle speed.
Clogged fuel lines or hoses - Service fuel lines and hoses.
Leaking cylinder head gasket - Install a new gasket.
Piston rings are leaking or defective - Change piston rings.

Engine overheated
Lack of engine coolant - Add coolant fluid to cooling system and also check it for leaks.
Engine oil level low - Fill up the oil to required level.
Dirty radiator core or defective radiator cap - Clean radiator or change cap.
Damaged or worn fan belt - Belt change is required.
Diesel engine is overloaded - Reduce engine load.

Oil pressure is insufficient
Lack of oil - Fill the crankcase with oil.
Oil filter clogging - Replace or service engine oil filter.
Different type of engine oil - Use correct viscosity oil.
Crankshaft bearing has excessive oil clearance - Bearing needs to be changed.
Oil pump malfunction - Repair or replace.

Abnormal engine noise or knocking
Engine oil level low - Check oil level and add oil as required.
Engine not warmed up - Warm up the engine.
Fuel injection pump timing is not adjusted - Set up as recommended.
Wrong adjustment of low idle speed - Correct low idle settings.
Fuel injectors are dirty or defective - Clean or replace fuel injectors.
Connecting rod is not aligned or worn - Connecting rod needs to be replaced or aligned.
Pistons are broken or worn - Pistons replacement required.

Hydrostatic Transmission Troubleshooting

Hydrostatic transmission noise
Transmission oil is contaminated or oil level is insufficient - Fill to required level or change the transmission oil.
Defective or not adjusted speed control pedal linkage - Repair or adjust linkage.
Defective relief valve - Replace valve as required.
Transmission is under excessive load - Load needs to be reduced.
Worn or defective parts of the hydrostatic transmission - After disassembly and inspection, replace defective components.

Power is insufficient
Lack of transmission oil supply - Fill the transmission housing to proper oil level.
Defective relief valve - Install a new valve.
Bent or unadjusted speed control pedal linkage - Change or adjust linkage.

Transmission overheats
Transmission fluid level is low - Fill the transmission housing to proper fluid level.
Transmission oil filter element clogging - Service or change transmission oil filter.
Clogged or damaged cooling components - Check all cooling components and repair or change if required.
Transmission overload - Reduce transmission load.

External fluid leaks
Damaged seals or gaskets - Seals and gaskets need to be replaced.
Internal transmission housing pressure is too high - Change defective parts.
Clogged oil drain line - Clean or replace drain line.

Hydraulics Troubleshooting

Hydraulic system overheated
Hydraulic pressure is incorrect - Adjust pressure as required.
Main relief valve is damaged or adjusted improperly - Adjust the valve or replace if necessary.
Hydraulic fluid contamination - The fluid must be changed.
Not enough hydraulic oil in the system - Add oil to the hydraulic system.
Hydraulic pump is faulty - Repair or change pump if required.

Lift arm does not lower or raise
Lift controls are defective - Repair or replace.
Hydraulic pump malfunction - Repair or change pump if required.
Hydraulic control valve is faulty - Install a new valve or repair it.
Defective hydraulic cylinder - Repair or install a new lift cylinder.
Hydraulic fluid level low - Fill the system to proper hydraulic fluid level.

Bucket won't move
Bucket tilt controls are damaged - Inspect and repair if necessary.
Hydraulic pump not working - Install new pump or repair it.
Hydraulic control valve is defective - Change or repair hydraulic valve.
Hydraulic bucket cylinder is defective - Replace or repair cylinder.
Hydraulic fluid level low - Fill up the hydraulic fluid.

Bucket or lift arm functions slowly
Hydraulic pump is defective - Test pump flow rate and replace pump if required.
Hydraulic cylinder oil leakage - Cylinder seals need to be replaced.
Hydraulic oil is insufficient - Need to add oil.
Hydraulic control valve is not set properly or defective - Set properly or repair.
Hydraulic pressure is low - Adjust pressure correctly.

Bucket or boom jerks when working
Hydraulic system is leaking air - Bleed air from hydraulic system.
Hydraulic oil filter element is dirty - Service or replace the hydraulic filter.
Hydraulic fluid is dirty - Change hydraulic fluid.
Cylinder tube or rod scoring - Replace failed component.

Hydraulic pump makes excessive noise
Hydraulic leaks or low oil level - Top up hydraulic oil or remedy leakage in system.
Hydraulic filter clogging - Clean or replace the filter.
Plugged suction line - Service the suction line.
Air trapped in hydraulic pump - Bleed air from hydraulics.
Pump components are damaged - Install new hydraulic pump or rebuild it.

Electrical Troubleshooting

Battery won’t charge
Electrical cable connections are loose or corroded - Tighten or clean electrical wiring connections.
Battery terminal clamps are defective - Terminal clamps need to be replaced.
Bad cell in battery - Use a new battery.
Defective or loose belt - Belt needs to be adjusted or replaced.

Starter turns slowly
Low battery voltage - Battery is drained, recharge it.
Battery won’t hold charge - Service charging system or install new battery.
Disconnected wires or corroded battery terminals - Check cables and service or change terminals.

Starter motor is not working
Battery is discharged or defective - Recharge or change battery.
Wiring harness is disconnected or improperly connected - Check wiring harness and connect as required.
Low battery output voltage - Battery is drained, charge it.
Starter motor is defective - Change or repair starter.

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WHEEL LOADERS SPECIFICATIONS

Wheel Loaders, Skid Steers, and Compact Track Loaders