NGK UR5 SPARK PLUG

Function and technical context

The NGK UR5 spark plug is part of the engine's ignition system, being responsible for generating the electrical spark that ignites the air-fuel mixture in each cylinder. It works in a particularly demanding environment: the marine environment combines constant humidity, salinity and thermal variations that accelerate the deterioration of the electrodes and the ceramic insulator. A bad spark plug causes misfires, loss of power, increased fuel consumption and starting difficulties, problems that on the high seas can compromise the safety of the boat. The NGK UR5 is specifically designed for Mercruiser engine ignition systems, guaranteeing direct compatibility with references 33-8134101, 33-97389, 75340, 8134101 and 97389.

When to replace this part?

The most common symptoms of a worn spark plug include difficult or repeated starts, jerking and backfiring during acceleration, increased fuel consumption, and black smoke or rough idling. For recreational marine engines, it is recommended to check and replace the spark plugs every season or every 100 hours of operation, whichever comes first, especially if the engine operates in high humidity or salinity conditions. Changing the spark plugs preventively before each season is an economical measure that prevents ignition breakdowns in navigation and prolongs the useful life of the coil and the ignition system in general.

Equivalent manufacturer part numbers