Marine Engines & Lube Oil Oral Questions — No-Start, Scavenge, Rings
Only what the full lessons do not teach — no-start drills, scavenge and mist scripts, ring logic, with signposts to purifier, reefer and batch lessons.
Key Principles at a Glance 5 points
- No-start diagnosis walks the air path first (bottle to distributor to valves to timing) before touching fuel.
- All-exhausts-up blames shared systems (air, timing, fuel quality); one-exhaust-up blames that unit (valve, cam, ports, rings).
- Scavenge-fire and mist answers follow fixed scripts: contain, cool sealed, inspect — never open hot steel.
- Ring-clearance answers state the direction of failure: small butt seizes, big butt blows by; small axial starves the seal, missing back clearance carries thrust.
- Reefer, purifier and batch-purification drills live in their full lessons — this file holds engine leftovers only, with links.
How to Answer — Air First, Then Fuel, Then Steel
Idea in one line: examiners pass the candidate who walks a fixed path — air, then fuel, then steel — instead of guessing parts at random.
Refrigeration, purifier and batch-purification drills already have full lessons — reefer servicing, purifier troubleshooting and the batch-rescue section inside it. This file keeps engine leftovers only.
1. Main Engine — No-Start and Running Faults
Idea in one line: an engine that will not turn lacks air or permission; one that turns but will not pick up lacks fuel, compression or timing.
Engine will not turn on air — walk the path.
Bottle pressure and valves, distributor supply, control air, turning gear out, distributor health, cylinder start valves, auto valve, reversal complete, lever fully home, bursting diaphragm intact, exhaust valves closing for compression.
Turns on air but will not pick up on fuel?
Filters and fuel pressure, dead cylinders, jammed regulator, bad-viscosity fuel, lost compression (rings, exhaust seating), pump and injector faults down to spill and relief valves.
All exhausts up vs one exhaust up?
All: scavenge temperature, fouled gas/air paths, timing, fuel quality, cooling and turbocharger fouling. One: its fuel valve, exhaust valve, cam, thermometer, ports, scavenge fire, rings, afterburning.
Cracked cylinder head — how do you know?
Blow-through water at indicator cocks, scavenge-space seepage, falling expansion-tank level, hot erratic jacket water, knocking, funnel sparks, white smoke — pressure-test to confirm.
Main-bearing wear-down and crankshaft location — how proved?
Wear-down by deflections; axial position by the thrust bearing. Underslung shafts buy alignment rigidity; rod bolts retire on hours (about 20,000) against fatigue.
For deflection readings, scavenge inspection and fire theory, see crankshaft deflection, scavenge & crankcase inspection and engine fires & explosions.
2. Scavenge Fire & Oil Mist — Fixed Scripts
Idea in one line: both scripts protect the steel first — contain and cool sealed, then inspect cold; opening hot steel feeds the fire or the explosion.
Scavenge fire — indications and first actions?
Affected exhaust up, turbocharger surging, trunk hot, smoky exhaust, revs falling. Slow to dead-slow, inform seniors, cut the unit's fuel, flood its cylinder oil, shut drains; stop and extinguish through fittings if it will not die alone.
Mist-detector alarm script?
Confirm and note the unit, inform seniors, dead-slow toward stop, evacuate and muster fire gear, wait out the cooling period sealed, then inspect with safe lamps for the hot spot.
Full fire physics and relief-door theory live in engine fires & explosions.
3. Rings, Sump & LO Temperature — Leftovers
Idea in one line: clearances fail in a direction — say which way and what breaks; sump level only moves when something enters or escapes.
The three ring clearances — significance of each?
Butt: small seizes and breaks, big blows by and drops compression. Axial: small starves the gas seal behind the ring. Back: none means the ring carries side thrust — friction and seizure.
Fitting discipline for rings?
Renew the pack with the scraper each withdrawal, mark up, expander on and off, joints staggered 180° (scraper opposite its spring joint).
Sump level rising? Falling?
Rising: piston-cooling water in, wrong gravity disc, storage filling valve passing, cooler leaking inward. Falling slowly: top up and hunt; falling fast: stop the engine — bedplate crack, piston-cooling leak, cooler, pipes, or an open crankcase return.
LO temperature high?
Bridge informed, ease load, verify overload state, check sump, cooler, purifier and heater-valve positions, shut the cooler bypass, clean the cooler, test the oil, hunt piping and clearances.
Ring overhaul and the full batch-purification and seawater rituals live in piston, liner & rings and purifier troubleshooting §7. Reefer drills live in reefer oil & TEV and reefer servicing.