• Marine Engine -vs- Auto Engine

    Safety Modifications

    Electrical systems[3]
    • Marine starter motor it has an internal screen to minimize the egression of spark movements.
    • Marine alternator differs from an automobile alternator it has an internal screen to minimize the egression of spark movements.

    Fuel systems (petrol/gasoline engines)[4][5]
    • Fuel pump vented if the fuel pump diaphragm ruptures, then the excess fuel will be directed into the carburettor. This kind of fuel pump is referred to as a marine fuel pump.[6]
    • Marine carburettor does not allow the overflow into the boat engine compartment.[7]
    • Spark arrestor on the air intake (carburettor or electronic fuel injection) a wire mesh screen on the spark arrestor cools any internal flame or spark created by back-fire, thereby preventing it from igniting fuel vapours inside the engine compartment.[8]

    Cooling systems
    • Marine automobile engines are water cooled; drawing raw water in from a pickup underneath the boat. In an open cooling configuration, the raw water is circulated directly through the engine and exits after passing through jackets around the exhaust manifolds. In a closed cooling configuration anti-freeze circulates through the engine and raw water is pumped into a heat exchanger. In both cases hot water is released into the exhaust system and blown out with the engine exhaust gasses.
    • The transmission oil cooler is cooled by raw water.

    Performance modifications

    • The marine distributor does not have a vacuum advance. Vacuum advance is normally actuated at high engine revolutions per minute (rpm) in low load situations - and this situation generally does not occur in the marine environment. Under normal operation, high rpm generally means high engine load.

    Engine rotation

    • Many marine engine crankshafts rotate in the opposite direction when compared to an automobile engine; RH rotation instead of LH rotation. This difference requires, depending on the engine design, a different camshaft, a different distributor gear, a different oil pump and different crankshaft seals.[citation needed]

    However, since the introduction of electronic fuel injection, and electronic engine management systems to marine engines this is not nearly as common. Engines equipped with a suite of electronics are LH rotation. The rotation is reversed for the propeller in the transmission.
    Comments 2 Comments
    1. ron livingston's Avatar
      ron livingston -
      how hard is it really 2 change a water pump on 85hp evinrude
    1. Tuso's Avatar
      Tuso -
      On d4 260 what causes oil to go into the coolant system