Outboard, Outdrive repair videos *Drawings *Illustrations

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OMC electric shift lower unit gearcase trouble shooting

Forward and reverse electrical clutch coil repairs

  • Forward or reverse coils
  • Forward or reverse springs
  • Outdrive coming out of gear
  • Water mixed in the oil
  • Water pump shaft splines stripped


Forward or reverse coils can be tested with ohm meter. They should read around 4 to 6 ohms. Ohm meter reading can very. It is important that the reading of both coils be similar in range. To test coil, place one ohm meter probe on green wire (forward coil), then second probe to ground or case. Repeat test step with blue wire (reverse coil).

Forward or reverse springs are best tested by applying 12 volts positive to the forward coil wire and the black to ground. Propeller shaft will need to be locked in place with 5/16 pin or screwdriver going thru pin area. Turn vertical drive shaft clockwise with torque wrench (set at 80 lbs.) Most broken springs will start to slip at less than 10 lbs. of torque.

Out-drive coming out of gear and engine revving high, can be caused by poor wire connections or shift switch contacts are going. Old shifter switch contacts often work intermittent as contact area gets worn out, much like the points of an engine. Note, if switch or wire temporary becomes open circuit and then closes starting engagement of coil at high RPM 1000 to 4000, It could break the forward spring. Reverse spring is broken most often by going from forward to reverse too fast, Thus not letting water drop rpm down on prop.

Water mixed in the oil ? The most common is fishing line in the seals.

Water pump shaft splines stripped. This shaft will break or seize up, if the upper drive shaft tapper bearing (located in the lower unit) is low on oil.