NGK ITR4A15 SPARK PLUG 8M2018369

Function and technical context

The NGK ITR4A15 spark plug (ref. 8M2018369) is part of the ignition system of Mercruiser four-stroke cycle petrol engines with multipoint injection (MPI), being directly responsible for generating the spark that initiates combustion in the cylinder chamber. Its iridium electrode guarantees a precise and stable electrical discharge even in the conditions of humidity, vibration and thermal variations typical of the marine environment. Poor ignition caused by a damaged spark plug results in irregular idling, loss of power during acceleration, increased fuel consumption and, in extreme cases, damage to the catalytic converter or injectors due to unburned fuel. In Mercruiser V6 and V8 block engines that work in salt water, keeping the ignition train in perfect condition is an essential condition for the reliability of the propulsion.

When to replace this spark plug?

The most common symptoms that indicate that the spark plugs of a Mercruiser engine need to be renewed are: difficult starting when cold, jerks or hesitation during acceleration, visible increase in petrol consumption and the presence of black smoke from the exhaust. NGK recommends checking the iridium spark plugs at each seasonal maintenance and replacing them according to the engine manufacturer's instructions, which for Mercruiser MPI engines is usually in the range of 300 hours of operation or every two seasons of heavy use. Replacing the complete set of spark plugs preventively, before obvious failures appear, avoids unexpected stops in navigation and protects the rest of the components of the ignition system against overloads.

Mercury/MerCruiser

Equivalent manufacturer part numbers