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Home / Wheel Loaders / JCB Wheel Loaders / JCB 426 HT

JCB 426 HT Troubleshooting

The JCB 426 HT wheel loader is powered by 359 cu.in (5.9L) Cummins BTAA5.9C six-cylinder turbocharged liquid-cooled diesel engine with a rated power of 142 hp (106 kW) at 2200 rpm. The JCB 426 HT is equipped with a four-speed powershift transmission, power steering system, hydraulic wet disc brakes, and 20.5R25 standard tires. The hydraulic system has a pump with fluid flow rate of 34.8 gpm (132 lpm). The hydraulic pressure is 3625 psi (250 bar). The wheel loader has a rated operating capacity of 9240 lbs (4190 kg) and tipping load of 18480 lbs (8380 kg). The maximum lift height is 153.7" (3905 mm) to hinge pin, and breakout force is 22240 lbs (10110 kg).

Engine Troubleshooting

Engine starts hard or doesn't start
Air in fuel tank - Bleed fuel tank.
Fuel filter element is dirty - Clean or replace the filter.
Damaged or dirty injection nozzles - Change fuel injection nozzles.
Dirt or water in fuel system - Drain water or flush dirt from the system.
Valve clearance is wrong - Need to adjust valve clearance.
Fuel injection pump damage - Change pump or rebuild it.

Engine starts and then shuts off
Dirty air filter - Service or replace the air filter.
Clogged fuel filter - Clean the filter or install new filter element.
Fuel injection pump is leaking - Repair any leaks.
Dirty or defective injectors - Inspect fuel injectors and change as required.
Fuel injection pump malfunction - Rebuild or change fuel pump.

Engine shuts off while running
Engine is cold - Normalize the temperature by warming up the engine.
Fuel filter is plugged - Service or replace the filter.
Air in fuel tank - Bleed fuel tank.
Fuel injection nozzles are damaged - Clean or change injection nozzles.
Fuel injection pump timing is wrong - Adjust fuel injection pump as required.

Engine stops at low idle speed
Low idle speed set incorrectly - Correct low idle adjustment.
Fuel injection pump damage - Repair or change injection pump.
Fuel injectors are faulty or clogged - Clean or replace fuel injectors.
The valve clearance is incorrect - Adjust to proper valve clearance.

Diesel power loss
Air cleaner is clogged - Install new air cleaner element.
Fuel injection nozzles fault - Test injection nozzles and change if necessary.
Fuel injection pressure is incorrect - Test fuel injection pressure and adjust it correctly.
Incorrect valve clearance - Check and adjust.
Low idle speed setting is incorrect - Correct the settings.
Fuel hoses or lines are dirty - Clean fuel lines and hoses.
Cylinder head gasket is blown - Install a new gasket.
Leaking or defective piston rings - Piston rings replacement required.

Engine overheated
Lack of coolant in cooling system - Refill to the correct level and inspect system for leaks.
Not enough engine oil - Checking oil level and add if necessary.
Faulty radiator cap or dirty radiator fins - Change cap or clean radiator.
Fan belt is broken or worn - Change the fan belt.
Engine is under excessive load - Load reducing required.

Insufficient oil pressure
Low crankcase oil level - Fill crankcase to proper oil level.
Oil filter clogging - Change or clean engine oil filter element.
Incorrect oil viscosity - Use correct viscosity oil.
Incorrect crankshaft bearing oil clearance - Change bearings.
Oil pump is worn or damaged - Remove and inspect oil pump.

Abnormal engine knocking or noise
Engine oil insufficient - Need to add engine oil.
Engine is not warmed up to required temperature - Warm up to required temperature.
Timing of fuel injection pump is incorrect - Adjust fuel injection pump as required.
Incorrectly adjusted low idle speed - Adjust low idle speed.
Damaged or clogged injectors - Clean or replace fuel injectors.
Connecting rod is worn or misaligned - Alignment procedure or replacement is required.
Broken or worn pistons - Pistons replacement required.

Transmission Troubleshooting

Low transmission oil pressure
Transmission oil insufficient - Check transmission oil level and add oil as required.
Transmission oil filter is clogged (if fitted) - Service or replace the transmission oil filter.
Stuck relief valve - Install a new valve.

Transmission is making noise
Low oil level - Need to add transmission oil.
Transmission oil contamination - Fill up with fresh transmission oil.
Incorrect backlash or gears are worn - Adjust backlash properly or replace the gears.
Worn or damaged bearings - Replace the bearings.
Worn or bent shift forks - Replace the shift forks.
Shaft splines are worn or damaged - Replace defective shaft.

Gears are hard to shift
Gear shift linkage is corroded or worn - Lubricate or replace shift linkage.
Damaged or worn gear shift forks - Replace the shift forks.
Defective parts in the gearshift mechanism - Replace defective parts.
Worn or unadjusted clutch - Clutch replacement or adjustment required.

Transmission oil leaks
Too much fluid in transmission - Excess fluid must be drained.
Damaged seals or gaskets - Install new gaskets or seal.

Hydraulics Troubleshooting

Hydraulic system is overheated
Hydraulic pressure is incorrect - Set pressure correctly.
Misadjusted or defective main relief valve - Adjust or replace the relief valve.
Hydraulic oil is dirty - Fill up with fresh hydraulic oil.
Lack of hydraulic fluid - Need to add fluid.
Hydraulic pump is worn - Change or repair hydraulic pump if required.

Boom fails to lift or drop
Lift controls are faulty - Change or repair.
Damaged hydraulic oil pump - Repair or change pump if required.
Faulty hydraulic control valve - Repair or replace hydraulic valve.
Hydraulic cylinder is broken - Repair or change hydraulic cylinder.
Insufficient hydraulic fluid - Add fluid as required.

Bucket tilt does not work
Bucket tilt controls are defective - Repair or change.
Hydraulic pump malfunction - Repair or change pump if required.
Defective hydraulic control valve - Repair or change hydraulic valve.
Damaged bucket cylinder - Replace or repair cylinder.
Low hydraulic fluid level - Add fluid as required.

Slow bucket or lift arm action
Hydraulic pump is faulty - Check the pump performance and replace it if required.
Leaking hydraulic cylinder - Correct leakage by changing the seals.
Hydraulic fluid is insufficient - Fill the system to proper hydraulic fluid level.
Hydraulic control valve is not set properly or defective - Adjust correctly or repair.
Hydraulic pressure has dropped - Correct adjustment is required.

Jerky operation of the bucket or boom
There is air in the hydraulic system - Bleed hydraulic system.
Hydraulic oil filter element is dirty - Service or change the hydraulic filter.
Hydraulic oil contamination - The oil must be changed.
Cylinder rod or tube is scratched - Change failed component.

Excessive hydraulic pump noise
Leaking hydraulic system or insufficient oil level - Remedy hydraulic leakage or refill oil as necessary.
Dirty hydraulic filter - Clean or replace the filter.
Dirty suction line - Suction line needs to be cleaned.
Air enters the pump - Bleed air from hydraulics.
Damaged pump parts - Rebuild or install new pump.

Electrical Troubleshooting

Battery cannot be charged
Electrical wire connections are loose or corroded - Service or tighten connections.
Defective battery terminal clamps - Terminal clamps need to be replaced.
Bad cell in battery - Change the battery.
Defective or loose belt - Change belt or adjust belt tension.

Starter motor turns slow
Battery power is low - Recharge the battery.
Battery is draining quickly - Battery needs to be serviced or replaced.
Battery cables are disconnected or terminals are faulty - Check battery wires and service or replace terminals.

Starter does not work
Battery is drained or defective - Recharge or change battery.
Wiring is incorrectly connected or disconnected - Inspect wiring and connect correctly.
Low battery capacity - Battery is drained, recharge it.
Faulty starter motor - Repair or change starter.

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WHEEL LOADERS SPECIFICATIONS

Wheel Loaders, Skid Steers, and Compact Track Loaders