Engine Basics Flashcards

What does the term 'cavitation' refer to in a boat engine system?

Answer: Formation and collapse of vapor bubbles around the propeller

Cavitation occurs when low-pressure areas around the propeller cause water to vaporize, forming bubbles that collapse and can damage the propeller.

Which type of cooling system circulates raw water directly from the lake or river through the engine?

Answer: Open (raw water) cooling system

An open raw-water cooling system draws water from the surrounding body of water directly through the engine and expels it with the exhaust.

Before starting an inboard gasoline engine, you should run the blower for at least how long?

Answer: 4 minutes

Running the blower for at least four minutes before starting an inboard engine ventilates the bilge and reduces the risk of gasoline vapor explosion.

What is the primary purpose of a boat's thermostat in the cooling system?

Answer: Maintain engine operating temperature

The thermostat regulates coolant flow to keep the engine within its optimal operating temperature range.

What does a 'four-stroke' engine complete in two crankshaft revolutions?

Answer: One complete power cycle (intake, compression, power, exhaust)

A four-stroke engine completes one full power cycle—intake, compression, power, and exhaust—in two full crankshaft revolutions.

Which fuel system component is most important to inspect for cracks or leaks before each outing?

Answer: Fuel primer bulb and hose

The primer bulb and fuel hose are common failure points; cracks can allow fuel leakage and vapor buildup that poses a fire hazard.

What indicates that a water-cooled outboard engine is circulating water properly after startup?

Answer: Water exits from the tell-tale (telltale) indicator

The tell-tale is a small stream of water expelled from the engine that confirms the water pump is functioning and the cooling system is operating.