Lubrication System — Most Asked Questions
31 questions asked about lubrication system across the General and Fn 4b and Fn 6 and Fn 3 papers, heaviest first. 2 of them are must-master.
Learn the system first
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1 lube oil test onboard?
Also asked: “Onboard lub oil test?”
Answer
Onboard lube oil testing monitors contamination (water, fuel, soot) and additive depletion (TBN, viscosity) so the oil charge is managed on condition rather than running hours.
- Water-in-oil tests: Quantitative test using a calcium hydride / carbide reaction cell (gas pressure rise measures water in % or ppm; condemning limit 0.2%–0.5%) and the quick qualitative crackle test on a hot plate.
- Blotter spot test (paper chromatography): A single drop on filter paper reveals soot loading in the dark core, dispersancy in the diffusion zone, and fuel/water in the outer translucent halo.
- Total Base Number (TBN): Measures remaining alkaline reserve in mg KOH/g using pressure-cell reagent kits; a drop of >50% from fresh oil condemns the charge.
- Viscosity comparator (flow-stick): Compares run-rate of used oil against fresh reference oil at equal temperature; allowable variation is ±15% to 20% (thinning indicates fuel dilution; thickening indicates soot or oxidation).
- Representative sampling: Drawn from the main circulation line at engine inlet at normal operating temperature; results dictate purifier throughput, batch sweetening, or complete charge renewal.
Surveyor follow-up: Crackle test is positive but the purifier has been running — where could water be entering and how do you differentiate fresh water from seawater?
Full theory: Marine Lube Oil Chemistry, Tribology & Microbial Degradation -
2 Types of lubrication?
Also asked: “Types of lubrication and where are they used”, “types of lubrication with example”, “Types of lubrication too”
Answer
Oil separates moving metal three ways — full-film hydrodynamic, pressurised hydrostatic, and thin-film boundary — delivered by splash, forced, gravity or mist systems.
- Hydrodynamic (full fluid film): motion drags oil into a wedge that carries the load — journal bearings running true; friction coefficient only about 0.002–0.012.
- Hydrostatic: same separation but pressure comes from an outside pump — for slow, heavily loaded parts that cannot build their own wedge.
- Boundary: film only molecules thick where full separation fails — rings at dead centres, gears on start-up.
- Shipboard systems: splash (small engines), forced/pressure circulation (main bearings), gravity header tanks (piston cooling, turbocharger coast-down), cylinder and oil-mist lubrication.
Surveyor follow-up: which regime is a crosshead guide in at slow ahead — and what in the oil proves it is surviving?
Full theory: Cooling, Lubrication and Fuel — Systems and the Tanks Checked Before Starting -
3 Too low fuel oil temperature
Answer
Cold fuel is thick fuel: poor atomisation, high injection pressures, smoky uneven running and knocking.
- Low temperature raises viscosity past the injector’s range — spray turns to jets that will not burn cleanly.
- Injection equipment strains against flow resistance, with pressure spikes that damage pumps and needles.
- Symptoms: difficult starting, black smoke, uneven running and cylinder knocking.
- Cure is heat, not pressure: raise fuel temperature to land 10–14 cSt at the injector and prove it on the viscometer.
Surveyor follow-up: temperatures correct yet one unit smokes — fuel system or air side, and what proves it?
Full theory: Lube Oil & Fuel Systems — Properties, Treatment & Changeover -
4 Compare the desirable qualities of the lubricating oil selected for each of the following duties
Answer
System oil cushions bearings, cylinder oil fights acids: alkalinity, detergency and stability split by duty.
- System grades need water separation, oxidation stability, anti-wear load carrying and moderate TBN.
- Cylinder grades need high TBN with outstanding retention plus detergency against deposits and varnish.
- High viscosity index and water tolerance steady both duties across temperature swings.
- Match the grade to sulphur and consumption: trunk engines share one oil, crossheads split the two.
Surveyor follow-up: trunk engine with crosshead cylinder oil aboard — fit, dilute or condemn, and why?
Full theory: Cooling, Lubrication and Fuel — Systems and the Tanks Checked Before Starting -
5 How will u knw water in lube oil
Also asked: “How will come to know water on lube oil of aux engine”
Answer
Water in oil shows as milky sight glasses, crackling hot-plate drops and falling viscosity — prove with analysis, remove by purification.
- Watch for milky colour, rising sump level and emulsion on dipsticks and sight flow.
- Crackle test on a hot plate sizzles with free water; lab analysis quantifies dissolved and free fractions.
- Viscosity falls, TBN washes out and bearings pit — trend both against the fresh-oil baseline.
- Centrifuge hot and slow, drain tank bottoms, fix the cooler or gland leak feeding the water in.
Surveyor follow-up: crackle positive with the purifier running clean — cooler, glands or condensation, and what proves it?
Full theory: Cooling, Lubrication and Fuel — Systems and the Tanks Checked Before Starting -
6 Why it is preferred to have timed cylinder lubrications in a slow speed 2 stroke engine and how it is achieved , highlighting development by two major makers
Answer
Timed oil lands between rings only when needed: Alpha and Pulse systems pulse small doses on load instead of drowning the liner.
- Untimed oil wastes down drains and cokes rings; timed injection cuts consumption with better film where it matters.
- MAN Alpha and Wartsila Pulse meter per-unit doses by load, speed and sulphur with electronic timing.
- Development runs from cam-timed quills to common-rail-style electronic lubricators with feedback.
- Prove by liner wear, ring pack cleanliness and drain-oil iron trending down after changeover.
Surveyor follow-up: liner wear high with timed lubrication fitted — timing, rate or sulphur match, and what proves it?
Full theory: Electronic Cylinder Lubrication: Alpha Lubricator & Pulse Systems -
7 Calcium carbonate (CaCO3) deposits may be caused by burning cylinder lube oil
Also asked: “• Calcium carbonate (CaCO3) deposits may be caused by burning cylinder lube oil”
Answer
Burnt cylinder oil leaves calcium carbonate ash: over-lubrication bakes base stock into crown and ring deposits.
- Excess feed rate leaves unburnt alkaline oil to bake on crowns, grooves and ports.
- Deposits raise wear, stick rings and foul scavenge ways while wasting expensive cylinder oil.
- Feed near 0.7–1.0 grams per bhp-hour in SAE 50 with TBN matched to fuel sulphur.
- Prove by drain-oil analysis, ring-pack cleanliness and consumption trending down after trimming.
Surveyor follow-up: deposits heavy with feed rate correct — oil grade, timing or cooling, and what proves it?
Full theory: Marine Lube Oil Chemistry, Tribology & Microbial Degradation -
8 Excess cylinder lubrication must be avoided
Also asked: “Excessive cylinder lubrication”
Answer
Extra cylinder oil buys scavenge fires, not safety: deposits, glazing and carryover follow overfeeding.
- Excess scraped down by rings beds carbon in the under-piston space waiting for blowback to light.
- Glazed liners, stuck rings and fouled ports follow with rising oil consumption for no wear benefit.
- Carryover oils the scavenge air and turbocharger path toward secondary damage.
- Feed to maker rate by load and sulphur with drain analysis proving the trim — uneconomic excess is also unsafe excess.
Surveyor follow-up: scavenge deposits growing with feed at minimum — timing, rings or grade, and what first?
Full theory: Cooling, Lubrication and Fuel — Systems and the Tanks Checked Before Starting -
9 How to test standby lub oil pump
Also asked: “How to test standby pump starting for ME lub oil pump when main engine is running”
Answer
Prove the standby by pressure drop: isolate the duty pump, watch auto-start on low pressure with alarms proved.
- Simulate falling pressure at the switch with the duty pump isolated — standby must cut in without hand help.
- Prove discharge pressure restored with bearings fed and alarms reset in order.
- Test with the main engine running only under controlled conditions with the chief’s permission.
- Log start pressure, run current and changeover time against the maker band.
Surveyor follow-up: standby hunts on test with pressure swinging — switch, air or pump, and what proves it?
Full theory: Cooling, Lubrication and Fuel — Systems and the Tanks Checked Before Starting -
10 Oil-water separator is not working correctly hence oil is being carried to the air receiver The cylinder lubrication is adjusted at high quantity, leading to carryover of oil with air The auto drain is malfunctioni
Also asked: “ Oil-water separator is not working correctly hence oil is being carried to the air receiver The cylinder lubrication is adjusted at high quantity, leading to carryover of oil with air The auto drain is malfunctioning”
Answer
Oil in the air system means separators, feed rate or drains have failed: drain coolers, trim oil, fix auto drains.
- Dead oil-water separators pass emulsion downstream into receivers and starting lines.
- Overfed cylinder oil carries over with air past rings into the same receivers.
- Failed auto drains let coolers flood upward into the air path instead of draining down.
- Drain separators regularly, trim feed to maker rate and prove auto drains — moisture corrodes receivers while oil migrates.
Surveyor follow-up: receivers oily with separators drained daily — feed rate, drains or cooler, and what proves it?
Full theory: Cooling, Lubrication and Fuel — Systems and the Tanks Checked Before Starting -
11 Lo lube oil pressure alarm action
Answer
Low oil pressure means slow down and prove flow: standby pump on, filters and sump checked, bearings watched before load returns.
- Air on suction, falling sump level, rolling with suction uncovered, dirty filters and open clearances bleed pressure gradually.
- Pump failure or auto-start failure drops it suddenly — start the standby and prove pressure rising before loading.
- Reduce speed or stop on persistent low pressure; pounding and hot bearings condemn continued running.
- Find the cause in order: suction, level, filters, clearances, pump wear — then log pressures against load.
Surveyor follow-up: pressure low with sump full and filters clean on a rolling ship — suction, clearances or pump first?
Full theory: Cooling, Lubrication and Fuel — Systems and the Tanks Checked Before Starting -
12 Asked to explain pulse lubrication system
Answer
Pulse lubrication squirts measured oil on timed cam strokes: each cylinder gets a small, metered charge where and when it is needed.
- The cylinder lubricating oil pump and the exhaust valve lubricating oil pump are driven off the main engine through a hydraulic motor.
- Each has small cam-operated plungers that deliver fixed quantities of oil to the quills at the right crank positions.
- Feed is therefore timed to the cycle, not averaged over the hour — the oil goes in just where the load is.
- Correct feed rate and grade matter more than any other cylinder-lubrication setting: too little scuffs, too much lacquers.
Surveyor follow-up: one quill dry with the rest pulsing and oil level steady — pump, quill or cam follower first?
Full theory: Two-Stroke Structure — Frame, Tie Rods, Liner, Piston & Crosshead -
13 By maintaining the correct feed rate and grade of cylinder oil
Also asked: “By maintaining proper feed rate of cylinder oils. Points to remember”
Answer
Cylinder oil is dosed by grade and rate: right viscosity and base number for the fuel, and enough to coat without fouling.
- Feed is typically quoted around 0.7 to 1.0 grams per brake horsepower-hour, matched to engine size and duty.
- Viscosity around the SAE 50 band with a total base number near 70 keeps the film on the liner in the right condition.
- A heavier fuel needs more alkaline oil and usually a higher feed, matched to the sulphur rather than to habit.
- Wrong in either direction is punished — too little and the liner scores, too much and the ports lacquer and the exhaust fouls.
Surveyor follow-up: heavy fuel in service with the same base number and feed as before — is the film being fed or starved?
Full theory: Cooling, Lubrication and Fuel — Systems and the Tanks Checked Before Starting -
14 Consumption of Cylinder oil per hour and per day ?
Answer
Cylinder oil consumption is counted, not guessed: measure the day tank drop, then divide by hours and check it against the feed setting.
- Consumption per 24 hours is the proper measure — drop counts vary in size between feeds and between oils.
- Per hour is that daily figure divided by 24, compared against the maker’s rate for the engine and load.
- Sight-glass drops are an estimate and a way of balancing feeds, not a measurement of consumption.
- Log it against hours and load: a rising daily figure with steady load means overfeeding, a falling one means starvation.
Surveyor follow-up: daily consumption up 30% with the feed setting unchanged — oil, injectors or the setting first?
Full theory: Cooling, Lubrication and Fuel — Systems and the Tanks Checked Before Starting -
15 Excessive cylinder lubrication which is drained to the scavenge spaces —
Answer
Too much cylinder oil ends up in the scavenge spaces: the trunk drains thick with oil, the exhaust fouls and the fire risk climbs.
- Overfeeding sends unburned oil down the liner and into the scavenge air, wetting the trunk and the turbocharger filter.
- Sludge collects in the scavenge spaces and drains, which is the engineer’s warning that the feed is wrong.
- Oil in the exhaust path raises exhaust temperatures, soots the turbocharger and can start an exhaust fire.
- Correct the feed rate and grade, then clean the scavenge and exhaust side — the oil will keep coming back until the feed is right.
Surveyor follow-up: oily scavenge drains with the feed proved on figures and the fuel changed to heavier grade — what first?
Full theory: Scavenge Fires, Trunk Safety & Relief Devices -
16 High temperatures within the cylinder cause deterioration in lubrication and possible damage to liner surface & piston rings. This may be the cause of piston crown burning
Answer
Heat breaks down the oil film: the liner, rings and crown cook together, so a burning crown is often a lubrication fault, not only a fuel one.
- Overheating evaporates and burns the cylinder oil, leaving lacquer and carbon on the liner and crown surfaces.
- Those deposits destroy ring elasticity, so the rings stick, the seal fails and the crown burns further.
- An overheated liner also warps, so the piston rubs where the bore has closed and scuffs where it has opened.
- Trace it back: injector, fuel valve, cooling flow, oil feed and scavenge air — the crown is the symptom, not the cause.
Surveyor follow-up: one cylinder crown burning with oil feed and cooling proved — injector, air supply or oil grade first?
Full theory: Cylinder Liner Wear, Calibration & Cold Corrosion -
17 How to check condition of lube oil
Answer
Oil condition is read by test, not by eye: viscosity, water, density and the crackle test on a hot plate tell the story.
- Viscosity by viscometer or timed discharge at a fixed temperature, compared with the reference oil for the grade.
- Water by crackle test — heated drops that pop prove free water; settling shows larger quantities.
- Density with a hydrometer at a controlled temperature, and appearance for sludge, carbon and varnish.
- For cylinder oil add a calcium-carbide water test, since water there destroys the film before it ever shows in the sump.
Surveyor follow-up: viscosity high and water low with the sump clean — is it oxidation, the wrong grade or the temperature?
Full theory: Cooling, Lubrication and Fuel — Systems and the Tanks Checked Before Starting -
18 If u have taken lube oil drum will you make enteries in orb
Answer
Taking lube oil in drums is a machinery-space oil operation, so it goes into the Oil Record Book Part I when it is an oil transfer.
- Oil Record Book Part I is kept by every ship of 400 gross tons and above, and by oil tankers from 150 gross tons.
- It is completed whenever machinery-space oil operations take place, including the transfer of oil into the ship.
- The entry records the type of oil, quantity, date, time, position and the tank or drum it came from and went to.
- The drum delivery note is retained with the entry — the book and the paperwork must tell the same story.
Surveyor follow-up: drum of lube oil landed with no ORB entry and no delivery note — which document is the missing one?
Full theory: MARPOL Annex I — Prevention of Pollution by Oil -
19 If we bunker lube oil in drum, do we have to enter in orb, wt things to enter
Answer
Yes for a transfer into the ship’s oil system, and the entry carries the type, quantity, date, time and tank receiving it.
- Oil Record Book Part I covers machinery-space oil operations, and a drum delivered into a lube or settle tank is one.
- Record the oil type and grade, quantity in litres, the date and time, the position, and the tank filled from the drum.
- Keep the delivery note or the supplier’s receipt with the entry as the supporting document.
- No entry is needed for a sealed spare drum simply stowed aboard until it is actually transferred.
Surveyor follow-up: five drums stowed and one transferred, with the book empty — is stowing recorded, or only transfer?
Full theory: MARPOL Annex I — Prevention of Pollution by Oil -
20 If you want to test a standby Main lube oil pump, while one Main lube oil pump is running, how would you do it?
Also asked: “• If you want to test a standby Main lube oil pump, while one Main lube oil pump is running, how would you do it?”
Answer
Test the standby on a running engine by starting it parallel, matching the discharge, then transferring the duty to it and watching the pressure.
- Confirm all parameters correct first — lube oil pressure and temperature, jacket water, sea-water cooling and rocker arm oil pressure.
- Warm the engine and verify everything is normal before any changeover is attempted.
- Start the standby and let it run against the line, watching the discharge pressure rise to match the running pump.
- Prove it holds pressure and temperature on its own, then record the test and change back to the duty pump if required.
Surveyor follow-up: standby started but discharge pressure stays below the running pump — is it primed, valved open or reversed?
Full theory: Cooling, Lubrication and Fuel — Systems and the Tanks Checked Before Starting -
21 Intermediate shaft lubrication
Answer
Intermediate shafts are lubricated by oil carried in a hollow bore, fed from the aft bulkhead, and checked at the seals and the stuffing boxes.
- The bore is drilled through the shaft so oil is carried inside it and thrown out at the bearings to form the film.
- Oil is supplied through a stuffing box at the aft end and thrown out by rotation at each bearing along the length.
- The aft end also carries a seal, so oil supply, seal condition and shaft bore are checked together in the ship’s routine.
- Oil thrown out at the wrong bearing is the usual symptom of a shifted or blocked bore, and it scores the bearing next to it.
Surveyor follow-up: oil thrown at the wrong bearing with the bore clear at the aft end — blocked bore, wrong hole or rotation?
Full theory: Oil Lubricated Stern Tubes — White Metal, Lip Seals and Header Tanks -
22 Lube oil in drum wali entry ko orb mai likhenge kya?
Answer
Lube oil taken in drums is written in the Oil Record Book Part I under machinery space operations — oil received and transferred.
- The entry carries the oil type and grade, the quantity in litres, the date and time, and the tank it was pumped into.
- Part I is for machinery space operations; Part II applies to an oil tanker’s cargo and ballast operations.
- The supplier’s drum receipt is kept with the entry so the quantity can be traced ashore if it is queried.
- Log the transfer when the oil enters the system — not when the drum was simply landed in the store.
Surveyor follow-up: drum received and logged, then transferred to the sump with no second entry — which operation was unrecorded?
Full theory: MARPOL Annex I — Prevention of Pollution by Oil -
23 Lubrication in ME ,timed untimed?
Answer
Main-engine cylinder lubrication is timed by cam to the cycle; systems are timed or untimed depending on the engine and maker.
- Timed systems deliver oil through cam-operated plungers at fixed crank positions, so the charge lands where the load is.
- Untimed systems meter a continuous flow set by load, with the amount controlled rather than the moment.
- Sulzer-type engines run the timed arrangement with individual quills and plungers per cylinder.
- Whichever the system, the answer is feed rate and grade matched to the fuel — the timing is only how it is delivered.
Surveyor follow-up: untimed system quoted for an engine with per-cylinder quills — is the feed load-based or cam-driven?
Full theory: Two-Stroke Structure — Frame, Tie Rods, Liner, Piston & Crosshead -
24 Lubrication in sg fittings on sg
Answer
Steering-gear fittings are greased to the maker’s schedule: the rams, the tiller and the manual steering gear all get their own treatment.
- Grease points are scheduled, not guessed — over-greasing works the grease out of the seals as fast as under-greasing starves them.
- Rams and their end caps are greased with the maker’s grade only, and the oil level in the reservoir is checked with the pump stopped.
- Tiller and manual gear connections are wiped, greased and kept clear of the paint and rust that stiffen them.
- Check the gear is free through full helm travel after greasing — a stiff tiller shows up as hunting and increased load on the pump.
Surveyor follow-up: tiller stiff after greasing with the pump running — free the air, reduce the grease, or adjust the tiller?
Full theory: Steering Gear Maintenance — Rudder Drop, Bearing Clearances and Overhaul -
25 Lubrication system for that
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26 Normal engine cooling and lubrication are maintained
Answer
Normal cooling and lubrication is the answer to why the standby machinery is kept live: heat, oil film and readiness.
- A standby set that has been stopped cold loses its oil film and its temperature, and starting it cold is what wrecks bearings.
- Keeping it warm and circulating preserves the film, so the standby can take load within seconds instead of minutes.
- On a motor ship this is the reason a standby generator is kept running rather than kept stopped and ready.
- It is a trade against fuel, and the answer is the availability: the set that is cold is the set that is not ready.
Surveyor follow-up: standby generator stopped and cold at sea with blackout drills weekly — which trade is being made?
Full theory: Cooling, Lubrication and Fuel — Systems and the Tanks Checked Before Starting -
27 R. START THE LUBE OIL PUMP & CHECK
Answer
Start the lube oil pump and check everything it feeds — pressure, temperature, flow, filter and the return it delivers.
- Start the pump and confirm the discharge pressure is at the maker’s figure with every branch open.
- Check the temperature at the bearing return, since a good pressure and a hot return means no flow where it matters.
- Watch the filter differential and confirm the bypass is shut, not carrying the oil round the element.
- Then confirm the return to the sump: pressure proved at the pump and oil arriving nowhere is the commonest failure.
Surveyor follow-up: pump pressure normal with no oil returning to the sump — where is the oil going first?
Full theory: Cooling, Lubrication and Fuel — Systems and the Tanks Checked Before Starting -
28 Sampling of lube oil
Also asked: “Lube oil sampling procedure and test”
Answer
Oil samples come from the running circuit, not the settled tank: a live sample is the only one that shows what the bearings are seeing.
- Sample after the purifier from a live tapping so the oil is representative of what is being delivered.
- Run the sample through the tests that matter — viscosity, water content, density, and particle count for the system.
- Water is checked by crackle or calcium-carbide test, and a settling test shows larger quantities without a kit.
- Trend it against hours and compare with the previous sample; a change is found in the trend, not in one reading.
Surveyor follow-up: samples taken from the settling tank show clean oil while the bearings are scoring — which tapping, and why?
Full theory: Cooling, Lubrication and Fuel — Systems and the Tanks Checked Before Starting -
29 Which engine has more Cylinder oil consumption 2 stroke or 4 stroke ?
Answer
The two-stroke drinks more: its cylinder oil is fed, used once and burnt, while the four-stroke recirculates the same oil round and round.
- In the two-stroke the piston has no scraper ring, so the oil is not recovered — once it has left the lubricator it is effectively lost.
- Cylinder oil is dosed by an external device through quills in the liner, and the charge enters the combustion space with the charge air.
- It then burns with the fuel, so the feed rate is quoted directly in grams per brake horsepower-hour.
- In the four-stroke the oil is splashed from the crankcase, scraper rings return it, and the same quantity serves the engine for ever.
Surveyor follow-up: two-stroke consuming less than the maker’s rate with a clean exhaust — is that saving fuel or starving the liner?
Full theory: Two-Stroke Structure — Frame, Tie Rods, Liner, Piston & Crosshead -
30 Will we put entries if we get lube oil in drums and if yes under what headline
Answer
Yes — under the Oil Record Book Part I, machinery space operations, at the heading for the oil transfer.
- Every ship of 400 gross tons and above other than an oil tanker keeps Oil Record Book Part I for machinery space operations.
- The entry records the type of oil, the quantity, the date and time, and the tank or system it went into.
- The delivery note or drum receipt is kept with the entry as the supporting document.
- Interim storage of a sealed drum is not yet an operation; the transfer into the ship’s system is what opens the book.
Surveyor follow-up: two drums transferred with the notes filed and no ORB lines — which record is the surveyor asking for?
Full theory: MARPOL Annex I — Prevention of Pollution by Oil -
31 high fuel oil pressure alarm
Answer
High fuel oil pressure means the supply is fighting a restriction: a blocked filter, a choked suction, or a delivery valve stuck open.
- A clogged suction strainer or filter is the usual cause, and the pump works harder against it for no more fuel.
- A delivery valve stuck open sends pressurised oil back to the suction, which can rupture a pipe or kill the pump.
- Relief valves on the discharge may be raised or lifted, dumping pressure and wasting pump capacity.
- Do not simply raise the alarm setting: find the restriction, and prove the pressure after cleaning rather than papering over it.
Surveyor follow-up: fuel oil pressure alarm on a new parcel with the filter renewed an hour ago — filter, strainer or delivery valve?
Full theory: Cooling, Lubrication and Fuel — Systems and the Tanks Checked Before Starting
Source: 123 written papers and surveyor oral banks, 24,613 entries, merged into 17,210 topics. Ticks are stored on this device only.