NGK CR6HS SPARK PLUG

Function and technical context

The NGK CR6HS spark plug acts as the final element of the ignition system, generating the high-voltage electrical discharge that ignites the air-fuel mixture in the combustion chamber of the outboard motor. It works in sync with electronic or magnet ignition, subject to extremely rapid ignition cycles and the corrosive and humid conditions characteristic of the marine environment. The integrity of the central electrode and the ceramic insulator is decisive for each combustion cycle to be complete: a spark plug in perfect condition ensures constant power, effective throttle response and adjusted fuel consumption. Its deterioration causes intermittent misfires, progressive loss of power and, in the most serious cases, the inability to start the engine in situations where the safety of the crew depends on it.

When to replace this part?

Unmistakable signs that a marine spark plug has reached the end of its useful life include difficult starting when cold, rough idling with vibrations or jerks, choppy acceleration, and a visible increase in petrol consumption. It is recommended to inspect the electrode and the insulating ceramic at each seasonal inspection, evaluating possible carbon deposits, erosion of the interelectrode space or cracks in the insulator. Preventive replacement every 100 hours of use or once a year is the most cost-effective intervention to ensure reliable ignition and avoid a breakdown at sea.

Mercury/MerCruiser