Practice Test Geeks(MST) Marine Service Technician Practice Test
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MST Outboard Engine Service & Gearcase Flashcards

6 cards from real MST practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 6 MST Outboard Engine Service & Gearcase flashcards as text

  1. An outboard engine's water pump impeller should be replaced at what interval as a best practice?

    Answer: Every 100 hours or annually, whichever comes first

    Rubber impeller vanes harden and crack over time, losing pumping efficiency; annual or 100-hour replacement prevents overheating before failure occurs.

  2. What symptom would a worn or damaged water pump impeller cause on an outboard engine?

    Answer: Overheating, reduced or absent water stream from the tell-tale, and possible engine alarm

    A failed impeller reduces cooling water flow, causing overheating that triggers the engine's thermal warning system and can cause severe engine damage.

  3. What special tool is required to properly torque the propeller nut on most outboard engines?

    Answer: A prop holding tool (prop wrench) and a torque wrench

    A prop holding tool secures the propeller from rotating while a torque wrench applies the OEM-specified torque to the prop nut.

  4. During a compression test on a two-stroke outboard, what is the acceptable minimum compression reading per cylinder?

    Answer: Above 90 psi and within 15% variation between cylinders

    Healthy two-stroke outboards typically produce 90–150 psi depending on the model; the critical factor is that cylinders are within 15% of each other.

  5. What is the function of the shift dog (or clutch dog) in an outboard lower unit gearcase?

    Answer: It slides axially on the prop shaft to engage the forward or reverse gear by locking to the bevel gear

    The shift dog is a splined sliding coupler that engages lugs on the forward or reverse bevel gear to transmit engine power in the selected direction.

  6. What is the correct process for removing a seized propeller from an outboard shaft?

    Answer: Apply penetrating oil, wait, then use a prop puller or wooden block with mallet — never use heat near seals

    Penetrating oil and a proper prop puller safely remove a seized prop without damaging the shaft threads or seals — heat or striking can cause serious damage.