Engine Noise: Internal ?

Troubleshooting Engine Noises – Internal

These are typical noises heard from classic truck engines that are not running properly. It is best to listen to internal noises with a stethoscope or hard metal rod placed against the ear and touched to various points on the engine. Always locate the source area of a noise before breaking down an engine

Knocking
Low octane fuel
Ignition timing incorrect (early)
Carbon deposits
Air/fuel mixture too lean
Vacuum advance springs weak
Manifold heat control valve stuck closed
Wrong spark plug range
Head gasket protruding into chamber
Valves overheated
Coolant temperature too high (overheating)
Valve Noises
Mechanical clearance too great
Sticking valve
Lifter damaged
Rocker arm face pitted
Weak valve spring
Warped valve stem
Valve seat not concentric with guide
Excessive stem-to-guide clearance
Loose timing gear
Piston Noises
Excessive piston pin clearance
Piston rubbing against cylinder wall
Top end of connecting rod bossing
Collapsed skirt
Piston pin too tight
Tapered cylinder bores
Connecting rod misaligned
Piston hitting ridge at top of cylinder
Carbon accumulation at top of cylinder
Broken ring
Excessive ring side clearance
Ring lands not properly relieved
Rod Noises
Excessive bearing clearance
Low oil pressure
Contaminated oil

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