MTC Marine Technician Engine Systems 3

Question 1

On a marine gasoline engine, what symptom typically indicates a failing water pump impeller?

Accepted Answer

Engine overheating and reduced raw water flow

Answer

A worn or broken impeller fails to pump sufficient raw water, reducing cooling capacity and causing the engine to overheat.

Question 2

Which tool is used to check crankshaft end play on a marine engine?

Accepted Answer

Dial indicator

Answer

A dial indicator mounted against the crankshaft flange measures axial (end) play when the crank is pushed fore and aft.

Question 3

What does a persistently low oil pressure reading on a marine engine most likely indicate?

Accepted Answer

Worn main or rod bearings allowing oil to bypass

Answer

Worn crankshaft or rod bearings increase clearance, allowing oil to escape the pressurized circuit faster than the pump can maintain pressure.

Question 4

A technician performing a compression test on a gasoline inboard finds one cylinder reading 90 psi while others read 150 psi. What is the most likely diagnosis?

Accepted Answer

Worn or damaged piston rings or valves on that cylinder

Answer

A single low compression reading points to a sealing problem in that cylinder—most commonly worn rings, a burned valve, or a leaking head gasket.

Question 5

What is the correct procedure when checking valve clearance on a marine diesel engine?

Accepted Answer

Check with the cylinder at TDC on the compression stroke and the engine cold or at specified temperature

Answer

Valve clearance is measured with the piston at TDC on compression (both valves closed) at the temperature specified by the manufacturer.

(MTC) Marine Technician Certification Practice Test

(MTC) Marine Technician Certification Practice Test

MTC Marine Technician Engine Systems 3