jcb G20 Operator's Manual page 130

Fuel is contaminated or incorrect grade diesel fuel
used.
Inlet and exhaust valve clearances set incorrectly.
Turbocharger noise.
Inlet and exhaust valve springs broken.
Worn crank/connecting rod bearings (knocking under
load).
Excessive camshaft bearing wear.
Worn or damaged pistons and/or piston rings.
One or more fuel injector worn or malfunctioning.
Gear train noise.
Loss of Pilot injection on one or more cylinders.
Cause
Fuel is aerated.
Fuel is contaminated or incorrect grade diesel fuel
used.
Electrical sensor fault.
Inlet and exhaust valve springs broken.
One or more fuel injector worn or malfunctioning.
Coolant operating temperature incorrect.
Cause
No fuel in supply tank.
Oil level incorrect.
Engine overload.
Throttle position sensor (TPS) system defective.
Fuel is contaminated or incorrect grade diesel fuel
used.
Turbocharger boost control pipe leaking or damaged,
or wastegate diaphragm ruptured
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Stop the engine.
Replace the fuel filters. Operate the engine with a
temporary supply of the correct grade of clean fuel.
Note: Dirty fuel will cause damage to the fuel injec-
tion pump and injectors.
Set the valve clearances to the recommended clear-
ances. Make sure the push rods are not bent or the
rocker levers are not severely worn.
Check turbocharger impeller and turbine wheel for
housing contact.
Check and fit new valve springs.
Check/replace rod and main bearings.
Check bearings (engine overhaul required).
Check piston assemblies (engine overhaul required)
Check the electrical connections at the injectors.
Visually inspect and measure gear backlash. Re-
place gears as required.
Use service master to disable pilot injections to iden-
tify audibly if they are still present.
Table 29. Engine - Compression Knocks
Remedy
Check the low pressure fuel system for loose con-
nections and possible air ingress points. Rectify and
bleed the fuel system.
STOP THE ENGINE.
Replace the fuel filters. Operate the engine with a
temporary supply of the correct grade of clean fuel.
WARNING: Dirty fuel will cause damage to the fuel
injection pump and injectors.
Check the electrical connections at the sensors.
Check and fit new valve springs.
Check the electrical connections at the injectors.
Refer to Table 44. and Refer to Table 45.
Table 30. Engine - Reduced Power Output
Remedy
Check the level in the fuel tank, use sight gauge or
dipstick. Replenish as required.
Check oil level.
Check for added loading from malfunctioning acces-
sories or driven units (alternator).
Check the throttle assembly
Stop the engine.
Replace the fuel filters. Operate the engine with a
temporary supply of the correct grade of clean fuel.
Monitor the engine performance.
WARNING: Dirty fuel will cause damage to the fuel
injection pump and injectors.
Check boost control pressure. Inspect and tighten fit-
tings, repair pipes, replace wastegate assembly.
9831/0650-3
Maintenance
Fault-Finding
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