With many military surplus Cummins marine diesel engines engines becoming available to boaters, Seaboard Marine has been involved with and performed a large number of 24V to 12V engine conversions. The QSB 380-GS (Government Service) has been the flagship engine of the Military and can be converted to a 12V platform with a small number of swappable engine components.

The following core electric engine components will need to be replaced:

22 SI, 12V, 3-Wire, Alternator with Pulley

12V Alternator

QSM 3 bolt Cummins Starter

12V Starter Motor

Marine Magnetic Switch / Starter Solenoid

12V Starter Magnetic Switch (Solenoid)

Cummins Marine Electronic Fuel Lift Pump

12V Fuel Priming Lift Pump

In addition, many times engines purchased in the surplus market will come without instrumentation and electronic throttle controls. If this is the case, the following components will also be required:

Throttle Control & Instrumentation:


SMX Electronic Throttle Control for Cummins Q-Series Marine Diesel Engines

SMX Electronic Throttle Control

Cummins Electronic Throttle Control Extension Harness

Throttle Control Harness

SMX J1939 Digital Display Panel

SMX Display Harness

Display Harness with 3-position Key Switch

SmartCraft & Engine Electronic Control Modules (ECM)

Mercury SmartCraft LogoFor customers who end up with receiving engines complete with existing SmartCraft harnessing and displays, many times an ECM “re-flash” will be required to prevent consistent faults from appearing during normal engine operation. This re-calibration of the ECM “should” prevent the module from broadcasting the “Low ECM Power” fault that would typically be encountered in an ECM that has an existing 24V calibration with 12V engine components. An ECM re-calibration can only be performed by a certified Cummins Marine technician with the proper version of the INSITE™ computer software & INLINE adapter. If you have a conversion project and have questions or need parts, please call Seaboard Marine at 800-200-BOAT.