MST Boat Systems & Maintenance 2

Question 1

What is the primary purpose of a marine raw-water strainer?

Accepted Answer

Filter debris before it reaches the engine cooling system

Answer

A raw-water strainer prevents debris, seaweed, and marine growth from clogging the engine's raw-water cooling circuit.

Question 2

Which type of marine battery is best suited for deep-cycle house bank service?

Accepted Answer

AGM deep-cycle battery

Answer

AGM deep-cycle batteries tolerate repeated discharge/recharge cycles and are designed for sustained loads rather than high-burst starting.

Question 3

A technician notices milky-white engine oil on a freshwater-cooled inboard. What is the most likely cause?

Accepted Answer

Water intrusion through a failed heat exchanger or head gasket

Answer

Milky oil indicates coolant or water mixing with the oil, typically caused by a failed heat exchanger or blown head gasket.

Question 4

What does a manifold vacuum test on a marine gasoline engine primarily indicate?

Accepted Answer

Overall engine health including valve sealing and timing

Answer

Manifold vacuum readings reflect combustion efficiency, valve seating, timing accuracy, and cylinder sealing simultaneously.

Question 5

On a stern-drive unit, what component transfers engine torque to the propeller shaft while allowing steering movement?

Accepted Answer

Universal joint (U-joint) assembly

Answer

U-joints in the stern-drive allow the drive unit to pivot for steering while continuously transmitting engine torque to the propeller.

(MST) Marine Service Technician Practice Test