Engine Basics Flashcards

What is the function of a boat engine's water pump impeller?

Answer: Circulate cooling water through the engine

The water pump impeller is a rubber vane that draws cooling water into the engine's cooling circuit to prevent overheating.

When should the engine's oil level be checked on a boat?

Answer: Before each outing with the engine off and boat level

Oil level should be checked before each outing with the engine off and the boat on a level surface to get an accurate dipstick reading.

What does a high engine temperature warning buzzer typically signal on an outboard motor?

Answer: Engine is overheating, possibly due to cooling water blockage

The overheating alarm indicates the cooling water flow is restricted, often by debris blocking the water intake, which can cause serious engine damage.

Which propeller characteristic most directly affects a boat's top speed?

Answer: Propeller pitch

Propeller pitch—the theoretical distance the prop advances per revolution—directly determines how fast a boat can travel at a given RPM.

Why is it dangerous to run an outboard engine in a poorly ventilated area?

Answer: Carbon monoxide exhaust can accumulate and cause fatal poisoning

Outboard engines produce carbon monoxide, a colorless, odorless gas that can reach lethal concentrations rapidly in enclosed or poorly ventilated spaces.

What is the purpose of flushing an outboard motor with fresh water after use in saltwater?

Answer: Remove salt deposits that cause corrosion in cooling passages

Salt crystals left in the cooling system can corrode internal passages and impair cooling; flushing with fresh water removes them.

On a two-stroke engine, oil is typically introduced by:

Answer: Mixing with the fuel or an oil injection system

Two-stroke engines lubricate by mixing oil with the fuel, either pre-mixed in the tank or delivered through an oil injection pump.