Marine Engines & Automotive Parts
May 29, 2011 7:14 PM | Tagged as Parts

 Using Automotive Parts In Marine Engines
Is this a good idea?
Most powerboaters know that their gasoline inboard or I/O engine is basically a GM, Ford or Chrysler block that has been marinized. Many engine parts are, indeed, interchangeable between boats and automobiles. There is one big exception, however. The engine in a boat is located in a closed area, where the engine compartment in a car is completely open at the bottom. Because of this, a boat has a problem with gasoline fumes that a car does not.

Gasoline fumes are heavier than air and, as a result, they sink downward. In a car they vent out the bottom of the engine compartment. In a boat, though, the fumes are trapped in the bottom of the hull (bilge). Because these fumes are highly explosive, all marine electrical components - starters, solenoids, alternators, etc., are sealed and cannot emit a spark or an arc into the engine compartment. The same components, for automobile use, are not sealed because the gasoline fumes have vented out the bottom of the engine compartment. So, will an automobile starter or alternator work on a boat engine? Yes it will - until an open spark from it ignites the fumes in the bilge!

The carburetor or throttle body on your car has an air filter on the top. On your boat, that same carburetor or throttle body must have a device called a flame arrestor on the top. A flame arrestor is a series of baffles that keeps an open flame caused by a backfire from entering your engine compartment. In the United States, this device must be U.S. Coast Guard approved and kept free of dirt and oily deposits.

So when the time comes, and you have a choice between a marine replacement part and an inexpensive automotive part, bear in mind that there is a major safety factor to consider. If you are already using automobile replacement starters or alternators, you are really pressing your luck! If a law enforcement agency discovers you are using automobile alternators or starters, or you do not have an approved flame arrestor installed, they will terminate your voyage right then and there.

Remember, use the correct parts and always run your blower for four or five minutes before starting your engine.

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