813964 Mercruiser HOUSING, REAR

Grounding Practices
Proper grounding for the electrical system is necessary for proper engine performance and reliability. Improper grounding will result in unreliable electrical circuit paths and in uncontrolled electrical circuit paths.Uncontrolled engine electrical circuit paths can result in damage to the main bearings, to the crankshaft bearing journal surfaces, and to the aluminum components.Uncontrolled electrical circuit paths can cause electrical noise which may degrade performance.In order to ensure proper functioning of the electrical system, an engine-to-frame ground strap with a direct path to the battery must be used. Connect the ground strap to the engine grounding stud to the frame and to the negative post of the battery.The engine must be grounded to the frame rail. Connect the battery negative post to the frame rail. From the frame rail, connect the ground wire to one of the following locations:
Cylinder head ground stud
Optional engine ground stud connectionThe engine must have a ground wire to the battery.Ground wires or ground straps should be combined at the studs that are only for ground use.All of the ground paths must carry any potential currents. The engine alternator should be grounded to the battery with a wire size capable of managing the full charging current of the alternator.
When jump starting an engine, the instructions in the Operation and Maintenance Manual, "Starting with Jump Start Cables" should be followed in order to properly start the engine.This engine may be equipped with a 12 volt starting system or with a 24 volt starting system. Only equal voltage for boost starting should be used. The use of a welder or of a higher voltage will damage the electrical system.
The engine has several input components which are electronic. These components require an operating voltage.This engine is tolerant to common external sources of electrical noise. Electromechanical buzzers can cause disruptions in the power supply. If electromechanical buzzers are used near the system, the engine electronics should be powered directly from the battery system through a dedicated relay. The engine electronics should not be powered through a common power bus with other devices that are activated by the Engine Control Switch (ECS).Engine Electrical System
The electrical system can have three separate circuits. The three circuits are the charging circuit, the starting circuit, and the low amperage circuit. Some of the electrical system components are used in more than one circuit.The charging circuit is in operation when the engine is running. An alternator creates electricity for the charging circuit. A voltage regulator in the circuit controls the electrical output in order to maintain the battery at full charge.The starting circuit is in operation when the start switch is activated.The low amperage circuit and the charging circuit are connected through the ammeter. The starting circuit is not connected through the ammeter.Charging System Components
Alternator
The alternator is driven by the crankshaft pulley through a belt that is a Poly-vee type. This alternator is a three-phase self-rectifying charging unit. The regulator is part of the alternator.The alternator design has no need for slip rings or for brushes. The only part of this alternator that moves is the rotor assembly. All of the conductors that carry current are stationary. The following components are the conductors: the field winding, the stator windings, six rectifying diodes and the regulator circuit.The rotor assembly has many magnetic poles with air space between each of the opposite poles. The poles have residual magnetism that produces a small amount of magnet-like lines of force (magnetic field). This magnetic field is produced between the poles. As the rotor assembly