Solenoid | Sierra 18-5820 Sierra Solenoid | 18-5820 12V isolated base starter solenoid for many Mercury, Mariner, Mercruiser, and Yamaha 4 stroke applications. Isolated base 12 volt Rubber grommets on mounting ears Replaces Mercury 89-818999A2, 89-818999A1, 89-850188T1, 89-850188A1, 89-825842A1 Replaces Mallory 9-15116