JCB Engine Knock / Internal Mechanical Fault

Loud knocking or metallic banging noise from the engine under load.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Worn big‑end or main bearings, Loose flywheel bolts, Injector over‑fueling causing detonation, Excessive piston slap

Safety: Severe knocking can precede catastrophic failure. Stop the engine immediately.

Basic checks: Verify correct grade and level of engine oil. Listen to determine if the noise is from the top or bottom of the engine.
Flywheel inspection: Check flywheel housing for loose bolts or damage.
Injector isolation test: A technician can isolate cylinders by cracking injector lines to identify a faulty injector causing knock.
Do not continue running: Internal bearing or piston damage requires engine strip‑down by a specialist.

Professional Required 5/5

Engine Short Block

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