Engine Compression & Cooling System Tools

What noise difference helps an automotive Mechanic's Stethoscope distinguish a bottom-end connecting rod knock from a top-end valvetrain lifter tick?

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 Correct IncorrectRod knock is a heavy, deep metallic thud that sounds at crankshaft speed (1x engine RPM) loudest on the oil pan; lifter ticks are sharp, light clicks at camshaft speed (1/2x engine RPM) on the valve cover.

What noise difference helps an automotive Mechanic's Stethoscope distinguish a bottom-end connecting rod knock from a top-end valvetrain lifter tick?

• Rod knocks only happen in reverse gear
• Rod knocks are deep hollow thuds at engine RPM loudest on the block/pan; lifter ticks are sharp high-pitched clicks at half engine speed
• Lifter ticks smell like burning rubber
• There is no sound difference