NC's - Marine Diesel Engines - Chapter 3 - Routine Maintenance
If you buy a vessel which has a coolant reservoir or heat exchanger that is made of brass, what can you do to stave off the effects of dezincification?
Drill access ports and install 1/4" fittings that accept pencil-type zinc anodes.
How do clean an Oil Bath air filter?
Empty the oil reservoir and clean it, as well as the filter mesh with kerosene or clean diesel fuel before refilling the reservoir and re-installing the filter mesh and cover.
What two fluids and filters should be changed before the vessel is put away for winter storage?
Engine oil and transmission fluid, to include associated filters and cleaning of centrifuges.
What should you do to ensure the alternator output and grounding cables never come loose and arc?
Ensure the nuts that connect the cables to the alternator have lock washers or Nylock nuts, and periodically check them for security (tightness).
Other than filling a new oil filter with new oil before you install it and risk making a mess in the bilge or contaminating it with dirty hands, how can you prime it?
Shutoff the fuel injector pump outlet and crank the starter for 15 seconds, which will serve to pump the new oil filter full of oil via the engine driven oil pump.
What do all water-cooled exhaust systems require to prevent seawater from back-flowing into the engine when it is not running?
Siphon breaks
What happens if you fail to regularly change a diesel engine's lubricating oil on time?
Sludge build-up in the crankcase and oil cooler passages, which will cause engine overheating and crankshaft and main bearing failure. Once the sludge forms, you can't get rid of it without removing and completely overhauling the engine.
Suction-side hoses to raw water pumps need to be made of what?
Must be made out of steel-spring reinforced rubber so they don't collapse under vacuum pressure.
T/F - If the vessel is regularly used on weekends or more frequently, diesel engine air filters should still be changed at least semi-annually, even if they appear to be clean.
TRUE
What is a major problem with siphon breaks, even if they are properly installed above the highest possible water line level in a boat?
The vent valves get clogged up with salt crystals, which causes them to spray salt water mist over the engine and/or into the engine compartment or electrical components or wiring.
The majority of diesel engine lift pumps are of the _________ type.
diaphragm
If you suspect the coolant tubes in your heat exchanger may have been compromised by galvanic corrosion, how can you verify that?
Drain the heat exchanger or oil cooler and look for water or oil in the raw water. If it's present, you have a leak.
What causes 90% of marine diesel engine problems?
Diesel fuel contaminated with rust, dust, dirt, water, or bacteria.
If the primary fuel filter you are replacing does not appear to be spotless after you remove it from the filter mounting bracket, what should you do.
Drain and flush the fuel tank and fuel feed line.
What preventative maintenance practice is recommended to preclude siphon-break vent valves from becoming clogged up with salt crystals?
Periodicially remove them every 2 weeks or so and rinse them out in warm water.
If you want to remove siphon-break vent valves altogether to preclude the chances of them becoming clogged with salt crystals, what can you do?
Replace them with a section of vent hose that has no valve, and run the free end into the cockpit or highest point on the vessel where they have no chance of ingesting salt water and becoming clogged.
Who assigns a lubricating oil's viscosity rating?
SAE = Society of Automotive Engineers
At low engine speed and load, very little fuel is injected into each marine diesel engine cylinder, so not all of the ______ drawn into the cylinder is consumed during combustion.
oxygen
A grain of salt has a width of around ______ microns.
100 microns
Just a __ % increase in the sulfur content of fuel taken aboard a diesel engine powered vessel can cause a __ % reduction in the service life of the engine's lubricating oil.
1% ; 50%
An oil cleaning centrifuge can remove contaminants that are as small in diameter as __ to __ microns in size.
1-2 microns
The paper filter inside the primary filter housing must be able to catch solid particulate contaminants in the incoming fuel that are as small as __ to __ microns.
1.) 10 2.) 30
What are two indicators that you may have a loose engine-driven belt?
1.) A rhythmic squealing sound shortly after engine start up. 2.) An an AC ammeter reading from the alternator that cycles up and down.
If you don't have an oil or fuel filter wrench aboard and you need to change the filters, what are two (2) things you can you use as an improvised alternative?
1.) A spare or used V-belt, which you can use like a strap wrench. 2.) Drive a large bladed slot screwdriver into the filter and use it to unscrew the stuck filter.
A bypass oil filter is suitable for installation on any sized diesel engine, and redirects about __% of the oil flow through it. These types of filters are capable of removing contaminants that are as small as __ micron in diameter.
1.) About 10% is tapped off the main oil pump supply using a restrictor valve in the oil line going to the oil bypass filter to ensure the engine does not suffer low oil pressure and oil starvation when this smaller particle filter starts to become clogged. 2.) Bypass filters can filter down to the 1 micron level.
With regard to potential fuel additives that may be considered by a vessel owner/operator in order to remediate suspected or verified water contamination inside a diesel engine fuel tank, what is the difference between an emulsifier and a demulsifier?
1.) An emulsifier causes the water to be dissipated into small micron-sized droplets, which will then be pumped into the engine via the fuel injection pump and injector nozzles, where it will theoretically be flashed to steam during combustion. 2.) A demulsifier causes small water molecules in diesel fuel to coalesce and form larger droplets, which then sink to the bottom of the fuel tank so they can be drained off or pumped out.
For engines equipped with heat exchangers, how often should the coolant be flushed and changed? Why?
1.) At least every two years. 2.) Because the corrosion inhibitors wear out faster than the coolant's anti-freeze chemicals.
During diesel engine pre-start checks, if you were to find an accumulation of particulate matter in the bottom bowls of your primary filters, what would you need to check next?
1.) Check the fuel tank (i.e., dip it with a clear tube or hose), and drain it and clean it if there are signs of contamination; 2.) Change all of the primary fuel filters. 3.) Check and clean or replace the filter screen inside the lift-pump housing. 4.) Change the secondary fuel filter.
What are 2 steps you should take to winterize the engine's fuel system?
1.) Check the fuel tank and primary, secondary, and lift pump screen filters for any water or sediment contamination and clean them out as required. 2.) Top off the fuel tank to minimize air in the top of the and minimize the chances of developing condensation, which will often result in water accumulating in the bottom of the tank during winter storage.
What are the two primary causes of raw water cooling system problems?
1.) Clogged or rusted out raw-water filter screens 2.) Raw water pump impellers with melted or broken blades
If your diesel engine has a heat exchanger, what is an alternate method of winterizing the raw water side of the cooling system?
1.) Close off the raw-water inlet sea cock valve. 2.) Disconnect the raw-water inlet hose from the sea cock and insert it into a 3-5 gallon bucket of 50:50 solution of distilled water and propylene glycol antifreeze. 3.) Start the engine and run it until you see the coolant mix discharge from the raw-water exhaust outlet.
What are 8 steps you should take as part of the engine's raw-water system's winterization process?
1.) Disconnect and drain all water from the system, including all hoses (and low point sags where it will accumulate) as well as the raw water pump impeller housing(s). 2.) Remove and clean the raw water strainer and drain the strainer housing. 3.) Remove the raw water impeller cover and impeller, and grease the impeller blades and shaft with marine grease, and leave the cover screws loose so no binding occurs during winter storage. Write yourself a note and post it on the instrument panel to remind you to tighten it when you put the vessel back into service in the Springtime. 4.) Run the engine for a few seconds with no raw water input to purge it of any residual water in the engine or piping. 5.) Drain the water-lift muffler if the engine is so equipped with one. 6.) Soak and wash the anti-siphon valve air valves in warm water to clean out the salt crystals. 7.) Break the engine exhaust pipe loose from the exhaust manifold and/or water-lift silencer and check for carbon buildup, and clean it out as required. 8.) Remove the raw-water injection hose from the exhaust elbow and inspect and clean it of any scaling or other debris.
What are (7) steps you should take to absolutely ensure clean fuel gets pumped into the diesel engine's fuel injection pumps and injector nozzles.
1.) Get your fuel only from reliable marinas or truck delivery companies, which pump a lot of fuel (ensuring their tanks remain clean and flushed) and also have fuel filters mounted on the pumps. 2.) Do your own small fuel sample before you fill up using a 2 to 4 quarter clear plastic or glass jar so you can spot any water or particulate contamination before making a decision to pump the fuel into your tank. 3.) Use a Baja-type filter funnel whenever refueling your tank(s). 4.) Keep the fuel tank topped off when the vessel is not being regularly used to cut down on the potential for water vapor condensation. 5.) Periodically add a biocide to the fuel tank(s). 6.) Change the primary and secondary fuel filters, as well as the lift-pump's filter screen at least every 6 months, even if they appear to be clean. 7.) Dip the tank every 30 days, or whenever the boat has not been run for an extended period.
What are three basic rules with regard to intermediate-level or yard -mechanic level maintenance, and when or if it should be performed?
1.) If the engine is running fine, then it's likely nothing is broken and needs fixing. In other words: "if it ain't broke, don't try and fix it". 2.) If intermediate-level or yard mechanic level maintenance is required, ensure the boat remains within the general area of the yard where it was performed in case the repair work needs some additional fine tuning, which happens frequently. 3.) Avoid any intermediate or yard-mechanic level maintenance for several months before going on an extended voyage with the boat.
When are problems with clogged fuel filters most prone to occurring? Why?
1.) In rough sea states 2.) Because any contaminants that have settled in the bottom of the vessel's fuel tank(s) will get stirred up and temporarily suspended in the fuel. Once that happens, they will be drawn into the primary and secondary fuel filters by the fuel lift pump.
What else can cause an alternator to blow out its AC to DC anodes?
1.) Inadvertently connecting the battery leads in reverse. 2.) Inadvertently grounding the alternator's output wire when it is running.
If you notice that your starter motor has rust or corrosion on the outer housing, what should you do?
1.) Investigate where the water in the bilge came from and try to stem it. 2.) Remove the starter motor, clean off the corrosion, and lubricate the pinion gear.
What are two (2) problems associated with diesel fuel that's been contaminated with water?
1.) It can cause corrosion of fuel injection pumps, injector nozzles, and cylinder components (valves, rings, piston heads, liners). 2.) It can support bacterial growth in the fuel tank, which can also created acidic byproducts and fibrous contaminants that damage fuel injection pumps, injector nozzles, and cylinder walls.
Besides its higher cost, what are two (2) other disadvantages of biodiesel in comparison to petroleum refined diesel fuel?
1.) It has a lower BTU content, so it does not provide the same amount of power per gallon as petroleum diesel fuel. 2.) It may not be ATSM D975 compliant for lubricity, and normal petroleum-derived diesel fuel serves to lubricate injector pumps and nozzles in addition to enabling combustion in the cylinders.
What are 8 advantages of synthetic engine lubricating oil over mineral (non-synthetic) oil?
1.) It is less volatile 2.) It has a greater high-temperature stability, which reduces sludge formation. 3.) It offers better protection under high-heat loads (e.g., when an engine overheats). 4.) It has a higher film strength, so it adheres to bearing surfaces better, reducing engine wear. 5.) It flows better at low temperatures (variable viscosity). 6.) It resists oxidation. 7.) It may improve fuel efficiency. 8.) It may last longer than mineral oil since its lubricity does not degrade as quickly, enabling longer oil change intervals.
What two things should you look for when inspecting engine hoses during winterization?
1.) Look for softening, bulging, or cracking, especially on the hot side connections of the coolant and exhaust hoses. 2.) Check the stainless steel hose clamps for signs of crevice corrosion by loosening them and looking for it in the section where the band goes into the worm screw housing. Re-tighten them when complete.
What 3 things should you do for house and starting batteries during winterization inspection?
1.) Loosen and inspect the battery terminals and posts for corrosion, clean them with baking soda solution if necessary, then apply some dielectric grease to them and re-tighten the connectors. 2.) Top off any wet cells with distilled water. 3.) Top off the battery charges and ensure this is done monthly during winter storage.
What are three precautions you must take if you retro-fit an electric oil change pump to the oil sump?
1.) Make sure the plumbing job between the sump drain and pump inlet is done to the highest standards, including a ball valve shutoff so you can close off the sump drain after the oil change is completed. 2.) Make sure the oil change pump you plumb in is rated to pump oil, and, if feasible, try to get one that is reversible so you can then use it to fill up the sump with new oil instead of having to pour it in through the engine oil fill. 3.) If the oil change pump you install is electrically powered, make sure it can never receive power while the engine is running.
What are 3 ways to prime a primary fuel filter after it's been changed or cleaned?
1.) Manually operated the engine driven lift pump plunger until it can no longer be actuated by hand. 2.) Install an electric fuel primer pump between the fuel tank and the primary filter. 3.) Install a DIESEL FUEL grade primer bulb in the fuel hose that runs between the fuel tank and the primary filter housing or manifold.
Although the marine environment is relatively free of airborne pollutants (e.g., dirt and dust), what are two conditions that can cause diesel engine air filters to become clogged more quickly than usual?
1.) Pets living aboard (i.e., pet hair) 2.) Operating the vessel near heavily urbanized or dusty coastal areas (e.g., offshore near dry climate or desert areas).
What should you do to the alternator and starter motors during your winterization checklist?
1.) Remove and clean the terminals and studs and apply dielectric grease to them before reconnecting. 2.) If there is any sign that starter motor got doused with saltwater, remove the starter and clean and grease the pinion gear. 3.) Spray the alternator and starter with WD-40 or CRC.
What 2 steps should you take to winterize engine control cables?
1.) Remove the control cables from the engine. 2.) Inspect the inner cables for any corrosion and replace them if necessary. 3. Clean and re-grease the inner cables and re-insert them into the outer sheaths and re-install them on the engine.
If the engine is equipped with a turbocharger, what 3 things should you do during your winterization inspection?
1.) Remove the inlet and exhaust ducting. 2.) Inspect the compressor and turbine for signs of soot or dirt deposits and/or corrosion and clean them if necessary. 3.) Re-install and tighten the connectors on the inlet and exhaust ducting.
Why are diesel engine cruising sailboats prone to encountering more problems associated with diesel fuel than motor yachts that mostly operate in continental US waters?
1.) Sailboats often visit 3rd world countries, which do not offer low sulfur fuel, and the high sulfur content of the fuel they take aboard creates soot (carbon) which turns the engine lubricating oil black very quickly and also creates sulfuric acid in the engine oil, which breaks down its lubricity and can damage bearings. 2.) Sailboat auxiliary engines are often only used only for docking or exiting moorings, so the engine oil often never warms up to its designed operating temperature to enable its detergents to work properly. 3.) Sailboat auxiliary engines are often run under low load for extended periods often for the sole purpose of charging the vessel's house batteries using the alternator. These low load operating conditions result in more carbon buildup, which is very hard on valves, and piston rings and can lead to loss of cylinder compression, overheat conditions, and premature engine failure.
Before removing the sedimenter cone and bowl from the primary fuel filer housing, what two things sould you do?
1.) Shutoff the fuel feed line from the fuel tank. 2.) Drain the fuel from the primary filter bowl using the thumbscrew.
Since many marine diesels are crammed into tight engine compartments aboard recreational marine vessels, if the airflow is restricted to the engine compartment, it will reduce the engine's ________ and/or __________ __________ , particularly at high engine speeds and loads.
1.) volumetric 2.) scavenging efficiancy
What are 3 steps you should take to winterize the engine block?
1.) Squirt some fogging oil into the intake manifold and crank the engine a few turns to lubricate the valves, rings and cylinders. 2.) Use a grease gun to apply grease to any Zerc fittings on the engine, if they are present (e.g., drive belt pulleys). 3.) Use some weather proof material to seal off all opening into the engine (e.g., air inlet, oil breathers, exhaust manifold outlet) and post a note on the instrument panel to remind you to remove them before the boat is placed back into service.
What are five diesel engine anomalous operating symptoms that need to be investigated and resolved ASAP before they turn into major repairs?
1.) Starting difficulty 2.) Higher or lower than normal oil pressure 3.) Higher or lower than normal cooling water or coolant temperatures 4.) Smoky exhaust (black or white) 5.) Unusual engine vibration or a "new" noises coming from the engine compartment
Two key advantages of installing either a centrifuge and/or bypass oil filter on a diesel engine are?
1.) Substantially reduced engine wear. 2.) Longer engine life.
What four (4) things should you check immediately before starting a marine diesel engine?
1.) The engine oil level including turbocharger if it has a separate reservoir. 2.) The engine coolant level (for heat exchanger equipped engines). 3.) The primary fuel filter bowls are clean, and the associated fuel filter shutoff valves are open. 4.) The raw water sea cock valve to make sure it's open.
If you are doing oil analysis on an engine to track its health, when and from what part of the engine should the oil samples be taken?
1.) The engine should be started and the oil should be warmed to normal operating temperature. 2.) The oil sample should be taken from the middle level of the oil sump.
What are three data points that the oil analysis laboratory you send your oil sample to will want to know?
1.) The make, type and grade of the oil. 2.) How many hours the oil has been in use since the last oil change. 3.) How much new oil has been added to the engine since the last oil change.
What four things should you check on a weekly basis when regularly using a diesel engine powered vessel?
1.) Transmission Oil Level 2.) Pulley belt tension 3.) Raw water intake strainer 4.) Air intake filter
In addition to the main engine oil filter, and any centrifuge or bypass filters, what other two filters might need to be changed or cleaned when the main engine oil supply is changed?
1.) Turbochargers, which may also have their own separate oil filters that tap into the pressurized oil feed from the engine oil pump. 2.) Crankcase breather filter (if the engine is so equipped)
What are the 9 steps for recommissioning a diesel engine vessel following removal from winterization storage?
1.) Unseal all engine openings that were taped over during winterization. 2.) Check the gasket or O-ring seals and re-tighten the raw water pump impeller housing cover. 3.) Replace all engine block and coolant system pencil zincs, if installed. 4.) Check each cell's water level and load test the batteries. 5.) Check coolant level in the heat exchanger and prime the cooling system, to include the raw-water side. 6.) Check the engine driven belt tensions and re-tighten the tensioners as necessary. 7.) If able to shutoff fuel flow to the injectors, crank the engine without starting it until oil pressure shows up on the gauge. 8.) Start the engine in neutral and verify good oil pressure, alternator output, and raw water exhaust outflow. 9.) After the boat has been in the water for a few days, check the engine alignment.
What are three (3) precautions you can take to minimize the chances of pumping contaminated diesel fuel into your vessel's fuel tank?
1.) Use a transparent glass jar to take a fuel sample from the pump nozzle before before filling up your tank. 2.) If getting fuel out of a 50 gallon drum (at a primitive, dip sample the drum using a section of clear plastic tubing with one end placed all the way down at the very bottom. 3.) Always use a Baja-type filter funnel inserted into the vessel's fuel fill port and monitor the fuel filter inside of it to make sure it is not heavily loaded with particulate matter contaminants.
What are three (3) reasons that adding emulsifiers to a fuel tank may be a bad idea to address a water contamination issue in a vessel's fuel tank?
1.) Water is not a good lubricant, so it could cause cylinder scoring if large droplets make it into a fuel injection pump or injector. 2.) When water droplets flash to steam in the combustion chamber, they could "steam clean" the area of the cylinder where this occurs, creating an unlubricated hot spot that can score the cylinder sleeve or piston ring. 3.) If emulsified water droplets remain inside the fuel injector pump or nozzles when the engine is shut down, it will likely create a corrosion problem (formation of rust particles) that could ruin these components when the engine is re-started.
All electrical wiring and connectors should be installed _____ the raw water exhaust elbow injection nipple. Why?
1.) above 2.) Because if this raw water hose connection leaks, it will spray or drip on the connectors and cause corrosion or shorting of the electrical wiring, connectors, or nearby components.
A marine diesel engine requires regular maintenance to ensure its longevity, which includes ensuring that it always has a fresh supply of clean ___, clean ____, and clean engine ___________ ___, as well as keeping the engine itself clean so that potential problems can be spotted and promptly addressed.
1.) air 2.) fuel 3.) lubricating oil
The drain plug in the bottom of the primary fuel filter bowl must be made of _____, even though the manufacturers often sell them with _______ ones, which are not ABYC compliant. Why aren't the latter ones ABYC compliant?
1.) metal 2.) plastic 3.) Because a plastic plug may melt in a fire, which would allow diesel fuel to drip from the filter bowl and into the fire, creating an even larger conflagration.
A diesel engine achieves maximum power output only when 100% of the ______ is consumed in each cylinder during combustion, however, in practice, diesel engines limit the amount of ____ ________, so only about 70 to 80% of the ______ is actually consumed.
1.) oxygen 2.) fuel injected 3.) oxygen
The amount of air drawn into the pistons on the intake stroke in turbocharged and/or supercharged diesel engines will vary with engine _____ and ____.
1.) speed 2.) load
Powerboats should have ___ or more primary filters, that are mounted on a ______-_____ ________.
1.) two (2) 2.) selectable-valve manifold
The problem with oil centrifuges is that they are powered (spun) by engine oil pressure, and as a result they are only suitable for installation on larger sized diesel engines that have a power rating of ___ to ___ HP or larger.
100-200 HP or larger.
The diameter of most bacteria are only about _ microns, so these microorganisms present the most significant challenge in preventing contaminated fuel from entering a diesel engine's fuel injection pump and/or injector nozzles.
2 microns
A white blood cell has a diameter of about ___ microns.
25 microns
Even if they appear to be clean, marine diesel engine primary and secondary fuel filters should be replaced every ______ hours, or more frequently in areas where fuel supplies may be subject to contamination (e.g., Bahamas, Caribbean, or Marinas with low fuel pump traffic).
300
What is the smallest size individual particle that a human with 20/20 vision can detect with the naked eye (i.e., without using a magnifier)?
40 microns
Because diesel engines create more sooty byproducts that use up detergents and additives to clean the engine, diesel engine oils must be drained and replaced more frequently than gasoline engine oils, and often as frequently as just __ hours of engine use.
50 hours (or less)
When reinstalling the center bolt on a sedimenter fuel filter after cleaning it, ensure the sealing ring seats correctly and torque it to no more than __ to __ foot pounds.
6 to 8 foot pounds
The secondary fuel filter, which is usually mounted on the engine just upstream of the lift pump, should have a paper filter element inside of it that is capable of intercepting both water droplets, and solid particulate contaminants with a diameter of between _ and __ microns.
7-12 microns
A human hair has a diameter of about __ microns.
70 microns
Heat exchanger coolant should be comprised of what?
A 50:50 mix of distilled water and anti-freeze coolant.
What TYPE of fuel filter does a diesel engine's primary filter need to be?
A SEDIMENTER type
What is an Oil Bath air filter.
A bowl-shaped filter that resembles a small cook pot with a top. The lower bowl section contains a reservoir for the oil and just above it is a thin wire filter element that resembles steel wool.
What is a good and cheap tool to use to prevent oil from spilling out of an old oil filter when performing an oil change on a boat equipped with an inboard diesel or gasoline engine?
A disposable diaper with elastic sides placed in a bowl shape underneath the old oil filter to be removed and the sump drain plug if you are not suctioning the oil out with an electric or dipstick tube pump.
What keeps the filter mesh in an Oil Bath air filter coated with oil?
A fine mist of oil is drawn up into the wire filter mesh with the intake air as it makes its first 180 degree turn above the oil bath reservoir.
What is biodiesel?
A fuel made from vegetable oil or animal fat that is combined with methanol.
If the primary fuel filter bowl is made of clear plastic, what additional safety feature must be added to the filter setup in order to be ABYC- compliant
A metal bowl-shaped heat shield must be mounted under the transparent filter bowl (s), which protects the plastic fuel filter bowl from melting for several minutes in case of an engine compartment fire.
If you have a raw water pump housing that is located in a confined space in the engine compartment which does not enable you to use an impeller puller, what can you use to remove the impeller as an alternative.
A pair of 90 degree needle nose pliers, that are torch-modified to be able to open the jaws up to a wide-enough gap that still enables you to open the jaws to grasp the axial portion of the impeller.
What is dezincification?
A phenomena whereby the zinc contained in brass (and other yellow metals) is leached out of the primary allow when subjected to the correct conditions (i.e., and electrolyte such as salt water). It causes the primary allow to become brittle and develop pin holes, that will allow leaks or breakage, particularly in coolant reservoirs and heat exchangers.
What is injector dribble?
A problem that occurs when the fuel supplied to the combustion chamber is not precisely cutoff at the end of the fuel injection pulse and fuel particles accumulate on the tip of the nozzle and drip into the cylinder after combustion and the power stroke has been completed.
What is the API rating of engine oil?
A rating assigned by the American Petroleum Institute that verifies the oil meets certain formulation quality standards?
Raw water filter housings should have what primary feature?
A see-through cover so you can easily inspect them for debris without having to remove the top cover before you start the engine.
What is ASTM D975?
ASTM International, formerly known as American Society for Testing and Materials (ATSM), is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services. D975 addresses the required characteristics of a range of diesel fuel grades produced in the US and Europe, which are based on a series of about 15 laboratory tests that include things such as sulfur content, cetane rating, viscosity, and lubricity.
If you had to fuel up at a marina that only had No. 1 diesel available, what could you do to increase the lubricity of that fuel after you filled up your tank?
Add a quart of TCW-3 (2 cycle) outboard motor oil for every 100 gallons you fueled up with.
Diesel engine lubricating oil should only be drained from the sump when?
After the engine (and oil) has reached its full operating temperature of at least 180 degrees, since the oil's viscosity while cold is too high and a large amount of it won't drain into the sump.
When operating in tropical or sub-tropical waters, how often should you check pencil or engine block sacrificial zincs for wear?
At least every 30 days.
If your vessel is equipped with a heat-exchanger cooling system, how often should you flush out and change the coolant?
At least every two years.
Why is algae contamination not a concern in a diesel engine fuel tanks?
Because algae is a plant and it needs sunlight to grow. There is no sunlight inside a closed diesel engine fuel tank.
Why is brass, which has been commonly used in older model engine coolant reservoirs such a huge concern?
Because brass contains a significant amount of zinc, and when you add hot salt water to it inside of a coolant system, it will result in dezincification.
Why is diesel engine lubricating oil required to be more durable than gasoline engine lubricating oil?
Because diesel engines operate at a higher temperature and compression ratio than their gasoline counterparts. This makes the oil work harder than gasoline engine oil, and serves to break down its lubricity and viscosity more rapidly.
Why is it important to know which grade of diesel fuel you are intending fill up your vessel's tank with?
Because diesel fuel lubricates the fuel injection pump's gears, injection cylinders and plungers, as well as the fuel injector nozzles themselves.
Why do two cycle turbocharged and/or supercharged marine diesel engines ingest more air than their equivalent four cycle engines?
Because each cylinder's exhaust valve and intake ports remain open for a combined total of about 160 degrees of crankshaft rotation between the end of the power stroke and beginning of the compression stroke, allowing the charged air to fully scavenge the cylinder exhaust gases. In effect, this is like having a 100 degrees of valve overlap on a four cycle engine.
Why is a ruptured air filter a big deal in a diesel engine?
Because even small amounts of fine dust particles passing through the air filter housing into to the fuel injector pump or engine can cause substantial damage in a very short time period..
Why should you inspect the engine feet and electrical connector couplings and wire during your winterization inspection?
Because if they have any engine oil, diesel fuel, or grease on them, these petroleum distillates will soften and eventually destroy the rubber or plastic, including electrical wire insulation.
Why has the EPA made such a big deal about reducing the sulfur content of diesel fuel?
Because it creates soot in the exhaust exhaust gases, which is an atmospheric pollutant.
Why did the EPA make a big push for reducing the amount of sulfur contained in diesel fuel starting back in the early 1990s?
Because sulfur burns and turns into soot particles, which then creates black smoke found in diesel exhaust smoke. This soot contains carbon and other organic materials that cause air pollution.
Why has the introduction of newer light-weight, high-speed, turbocharged diesel engines made the use of API and SAE acceptable grade lubricating oils so much more important?
Because they are subject to even higher RPMs and compression ratios than older model "iron block" diesels, and they have smaller oil sumps.
When should you check the primary fuel filter bowls?
Before each engine start, and ALWAYS after the engine is shut down. If you see any visible signs of water or dirt in the bowl(s), you should investigate and clean and flush the fuel tank before starting the engine.
What problems does a dribbling injector cause?
Black or white smoke coming from out of the overboard exhaust port because the dribbled fuel is not fully burned. This un-burned diesel fuel can leak past the piston rings because its much thinner than engine lubricating oil. It then acts like a solvent, which can wash away the engine lubricating oil from the cylinder walls. This condition can lead to ring failure and cylinder scoring, which will be eventually be evidenced by the engine overheating, loss of power, and piston seizure.
How is a diesel fuel's lubricity tested?
By using a High Frequency Reciprocating Rig (HFRR), which places a specified load on a bearing that is lubricated with diesel fuel and run for a period of 90 minutes. After the test run, the bearing surfaces are examined with an electron microscope to measure the length of the longest scoring scars.
The first two letters and the first number that appears on the API "donut" for lubricating oil that meets API standards for use in diesel engines should be ___-_ or greater.
CF-4 or greater.
What are some engine problems that will occur if a rich burn condition is not quickly rectified in a marine diesel engine?
Carbon build-up on the valves, exhaust passages, inside the engine cylinders (rings), oil sump, and the turbocharger's oil supply.
After a primary fuel filter and/or oil filter change has been completed, and the engine instruments appear to be operating normally, what's an additional check you should make to be absolutely sure your workmanship was up to par?
Check the primary fuel filter housings and oil filter to make sure there are no leaks while the engine is running and they are under normal operating pressure.
What is the most common failure in marine electrical systems?
Dead batteries
Why should you use anti-freeze that is made from propylene glycol vice ethylene glycol?
Ethylene glycol is an environmental toxin that causes skeletal deformations in mammals. It also has a sweet smell and flavor that attracts pets and small children, who may drink it if it puddles on hard surfaces. Upon ingestion, it is oxidized to glycolic acid, which is, in turn, oxidized to oxalic acid, which is toxic. It first affects the central nervous system, then the heart, and finally the kidneys, and in sufficient amounts is fatal to humans and animals.
How often should diesel engine oil be changed?
Every 100 - 250 hours depending upon things such as the amount of sulfur content in the fuel that was burned, as well as how the engine was operated (e.g. light load and cold operation = more frequently). Sailboats and other vessels where the engine rarely reaches full operating temperature due to frequent starts and stops should have their oil changed about every 50 hours because of higher carbon and water condensation buildup in the oil sump.
T/F - EPA emission standards requirements have forced petroleum refiners to substantially lower the sulfur content of diesel fuel from 500 ppm down to 15 ppm in ultra-low sulfur diesel (ULSD) since 2007. This is now a significant concern to diesel engine powered vessel owners and operators because sulfur in the fuel serves as a vital component to maintaining the fuel's lubricity.
FALSE. The ULSD concern is actually due to the hydro-treating process employed by the refiners to remove most of the naturally occurring sulfur from the fuel. This treatment process is what actually causes a reduction in the fuel's lubricity, which is necessary to lubricate fuel injector pumps and injectors.
T/F - Pencil or engine block zincs will always last longer in tropical or sub-tropical climates.
FALSE; the rate of deterioration is directly proportional to water temperature and salinity of the water flowing through the heat exchanger or engine block.
Diesel engine lubricating oil filters are designed to catch and trap particles that are greater than __ microns in diameter, but studies have shown that particles in the range of __ to __ microns in diameter are the ones that cause the most engine wear.
Filters trap particles >/= 30 microns, but most engine damage is done by smaller particles in the 10 - 20 micron range.
If you are replacing a spin-on primary fuel or oil filter with a new one, how tight should you torque it?
Hand tighten the new filter and then torque it another 3/4 turn with a filter wrench.
While diesel engine manufacturers normally specify periodic component overhaul intervals for things such as fuel injectors and valve clearances, what is a more relevant factor in determining them?
How the engine is operated. For example, if it's low load and short interval (like a sailboat's), then overhaul intervals may need to be more frequent to clean off the carbon.
If a primary fuel filter uses a wing nut to attach and snug it to its filter housing, what should you be concerned with after you have completed a filter change.
If you did not tighten the wing nut sufficiently, you are likely to suffer engine performance problems since the filter housing will suck air into the fuel supply going to the lift pump and secondary filter before it arrives at the fuel injector pump.
Where are you most likely to find sacrificial zincs on a marine diesel engine?
In the coolant reservoir and in the engine block.
Ideally, where should raw water filter screen housings be located on a vessel?
In the engine compartment, above the water line so you can remove and clean the filter screen without having to shutoff the sea cock valve. If it's below the waterline, then the sea cock valve should be in close proximity to the inlet filter screen housing so you can quickly shut it off if you forget to do so before removing the top cover of the filter screen and wind up with a flooding bilge.
If a diesel engine powered vessel has been left sitting unused without any preventative maintenance for as little as just a few months, what should be done before you change out any fuel filters?
Inspect, drain, flush and clean the fuel tank(s) because they will likely be contaminated with water and/or or bacteria.
What are some additional features that diesel engine makers employ to address the < 30 micron contamination problem in engine lubricating oil.
Installation of oil centrifuges and bypass filters, which are able to remove very minute particles from the oil down in the single micron range.
What does a selectable-valve fuel filter manifold enable on a diesel engine primary fuel filter system?
It allows one of the primary fuel filters to be shut off (isolated) from the fuel tank feed line so it can be changed while the engine is running.
Why should a vacuum gauge be mounted between the primary fuel filter(s) and/or manifold and the fuel lift pump?
It allows the vessel operator to monitor the vacuum pressure in the fuel supply line between the primary filter(s) and/or manifold and the secondary (engine-mounted) filter. If the vacuum pressure starts to increase, then at least one of the primary fuel filters in the manifold setup is becoming clogged.
Describe how a SEDIMENTER-type filter functions.
It forces the incoming fuel to make a sharp 180 turn around a conically-shaped deflector plate shortly after it enters the filter housing just before it is forced up through the paper filter element. This causes any solids and water droplets to be flung outward towards the sides of fuel filter bowl and then settle in the bottom of the bowl.
Biodiesel is considered to be a "drop-in" fuel. What does that mean?
It means it is functionally equivalent to petroleum diesel fuel and is fully compatible with existing petroleum infrastructure.
Why is it so important to clean off all dirt from the primary fuel filter and/or oil filter mounting bracket and filters before you unscrew the old filter and replace it.
It reduces the chances of contamination getting onto the new filter or inside the filter housing when you reinstall the new filter.
What happens when rust, dust, or dirt gets into a jerk-type or distributor-type fuel injection pump?
It scores the fuel injection pump's plungers and cylinder walls, which will quickly lead to to fuel pressure blow-by, loss of fuel pressure to the injectors, and uneven fuel injection pulses in the cylinders.
Higher-end primary fuel filters often incorporate an electronic probe that is wired to the vessel's electronic warning system. What is the purpose of this probe?
It senses when water contamination in the primary filter bowl has become too high.
What would happen if you moved the battery switch to the "off" position while the engine is running?
It will blow the diodes in the alternator, unless the battery switch has a "make-or-break" design feature that ensures at least one of the batteries is always connected to the alternator to accept a charge.
Where would you normally find a fuel lift pump filter screen?
It will usually be integrated into the lift pump housing (mounted on the engine block), immediately upstream of the lift pump's diaphragm or impeller.
What is the primary reason that biodiesel is not normally found at marinas?
It's more expensive to produce than diesel fuel refined from petroleum (crude oil).
What is the maximum sulfur content of LSD and ULSD, respectively?
LSD = 22 ppm / ULSD = 15 ppm
What does a partially clogged air filter cause?
Loss of airflow (oxygen) going to the engine, and eventually, a loss of engine power, particularly if the airflow obstruction is greater than 20-30%.
On an an analog-controlled diesel engine (i.e., no Electronic Fuel Injection (EFI)), what would be an indicator of a clogged air filter.
Loss of engine power and black smoke coming from the exhaust (indicating a rich burn).
Before diluting anti-freeze with distilled water and adding it to your coolant reservoir, what should you do?
Make sure it's not pre-mixed and already diluted. Some of them are.
Before fueling up with biodiesel, what should you do in advance?
Make sure your diesel engine is approved to use biodiesel by the manufacturer and that doing so will not void the engine's warranty.
Why aren't synthetic lubricating oils recommended for marine diesel engines?
Marine diesels burn dirtier than gasoline engines and accumulate more soot in the oil, so extending oil change intervals that are otherwise enabled by synthetic oils is not recommended.
When should the coolant be mixed?
Mix it before you pour it into the coolant tank to ensure you get the correct ratio.
If you modify your siphon-vent to remove the valve by installing the open end in the cockpit or a higher point on the vessel, and you notice that this vent tube still "weeps" water, what is the problem?
Most likely the air relieve vent check valve has become clogged with carbon soot from the engine, so you have a problem with a rich mixture in the engine that is most likely related to fuel injectors or injection pumps.
What are the two grades of diesel fuel most commonly available in the US and Europe?
No. 1 and No. 2
What is the difference between No. 1 & No. 2 grades of diesel fuel?
No. 1 has lower viscosity and lubricity than No. 2 because it is commonly used in cold weather climates to prevent fuel gelling.
What should you check immediately after every marine diesel engine start?
Oil pressure and raw water exhaust outflow to make sure the cooling system is functioning properly.
How large is one micron?
On millionth of a meter (0.0001 mm) or 0.000039 of an inch, which is forty times smaller than a perfect human eye can see.
T/F - Most modern diesel engines built after 2006 do not have engine or heat-exchanger sacrificial zincs because the manufacturers have succeeded in getting a tight-enough control over the types of different metals used inside the engine to prevent internal galvanic corrosion.
TRUE
T/F - Raw water cooling systems are one of the more common sources of trouble with marine diesel engines.
TRUE
T/F - The pistons of a naturally aspirated marine diesel engine ingest the same amount of air on each intake stroke, regardless of the engine's speed or load.
TRUE
If you have a condition where your vessel's batteries are suffering from continuous low charge conditions, what should you check?
The belt tension on the alternator.
What can happen if you leave an engine-drive belt in a loose state over a prolonged period?
The belt will heat up, become brittle, and eventually break.
What may be the only sign that ULSD has damaged a diesel engine that was manufactured before 2007 when this fuel was mandated for nationwide implementation with in the US?
The engine suddenly becomes hard to start, and or the high pressure fuel injection pump fails.
What is a particular problem with loose alternator belts?
The friction of the loose belt will cause the alternator pulley and shaft to heat up from the friction caused by the slipping, which can de-magnetize the alternator and completely ruin its electrical generating output.
What is the most expensive component on a mechanically-controlled diesel engine?
The fuel injection pump(s); because they are a precision piece of equipment, built with machining tolerances that are as precise as those of a Swiss watch.
Many diesel powered vessels, particularly sailboats, have high-output alternators, which need to have "thick" cables to handle the electrical current they generate. What is a common problem associated with these heavier cables?
The nuts that hold them onto the alternator's output and ground studs tend to vibrate loose, which causes arcing that can melt the output stud, causing the output cable to drop off of the alternator. If the battery isolation switch is not tripped, you then have a "hot" red cable from the battery laying atop the engine or down in the bilge, which can cause an electrical fire because its a dead short circuit.
What is the ATSM D975 standard for lubricity, as determined by the HFRR?
The scoring scars after the HFRR test is completed can be no longer than 520 microns, but some engine manufacturers may require a lower value of 450 microns, necessitating the addition of a lubricity additive to your vessel's diesel fuel tank.
With regard to worm-screw type hose clamps commonly found on marine diesel engine cooling systems, what is a common problem?
The screws used are often not of the same grade of 300 series stainless steel and they will rust or suffer from crevice corrosion.
If the secondary fuel filter gets clogged with particulate matter that is too small to be filtered out by the primary filters, what can happen?
The secondary filter may collapse (implode), which would then allow contaminants to bypass it and make their way into the fuel injector pump and nozzles. If this happens, it will also usually cause injector nozzles to dribble.
Why are diesel engine lubricating oils different than those used in gasoline engines?
They are specifically formulated to handle the higher compression ratios and operating temperatures found in diesel engines, and to hold engine soot in suspension to mitigate the effects of acids and other harmful byproducts that are created during diesel fuel combustion.
In operating areas that are prone to a large amount of sea life or seaweed that can clog raw water inlet screens, what is a nice feature you should consider installing on the vessel?
Two independent raw water inlets (sea cocks) and two filter screen housings with an isolator valve manifold. Just like a manifold on the primary fuel filters, this will enable you to shut off a clogged raw water inlet screen filter housing and clean it out while the engine is running, while the other (unclogged) filter housing continues to supply raw water to cool the engine and components.
When you inspect coolant system hoses for bulging or cracking, what else should you do?
Unscrew the hose clamps and inspect the screws for signs of crevice corrosion, since even those that are 316th stainless will be subjected to this because they have no breathing space inside the screw holder to form the protective chromium-oxide layer that makes them rust-resistant.
Other than draining used engine oil from the crankcase by removing the drain plug at the bottom of the oil sump (and making a big mess in the bilge), what are two alternative options?
Use a "sucker" pump to vacuum the oil out through the dipstick tube, or plumb an electric pump into the bottom of the oil sump via the drain plug opening.
If you own a pre-2007 diesel engine, and are unable to verify that the fuel you are about to pump into your tanks meets the ASTM D-975 lubricity standard, what can you do?
Use a synthetic blend lubricity additive that is approved by the engine manufacturer and has been proven to meet the ATSM D-975 lubricity standard through testing and verification conducted by an independent third party laboratory.
How can you check belt tension on an engine without using a tension gauge?
Use your finger to apply pressure on the alternator drive belt. It should not depress more than 3/8 to 1/2 of an inch on any engine driven belt.
If you have a wet bilge, what is concern with regard to the starter motor?
Water from the bilge can splash up and land on the starter motor pinon gear, causing both electrical and corrosion problems.
When is a clogged primary fuel filter most likely to occur?
When the vessel is operating in a rough sea state because water, rust, dirt, or bacteria that has settled in the bottom of the fuel tank will get stirred up and sucked into the primary fuel filters.
When should heat-exchanger pencil or engine block zincs be replaced?
When they have decayed to 50% of their original size.
What's an easy way to check to see if a marine diesel engine compartment airflow is substantially restricted?
While underway, run the engine and/or the diesel AC generator up to full speed and full load for a few minutes, then crack open the engine compartment door to see if there is a noticeable suction/vacuum present. If a vacuum pressure is detected, then you will need to increase the size of the air inlet going into the engine compartment.
The sedimenter cone and bowl of the primary fuel filter should be cleaned with _____ ______ ____.
clean diesel fuel
All fuel and coolant system hoses located below the waterline on a marine vessel must be ______-_______.
double-clamped
Diesel fuel lift pumps will normally include a ______ _____ that serves as the last line of defense to prevent particulate matter from entering the high-pressure fuel injection pump.
filter screen
On average, turbocharged two cycle marine diesel engine ingest _____ times as much air as naturally aspirated engines.
four
Just two ___________ of fine dirt or dust ingested into a diesel engine can cause significant internal wear that could require a complete rebuild.
tablespoons
A 10 micron fuel filter can filter out particles that are roughly the size of the diameter of a single speck of ______ ______, which is four times smaller than the naked eye can detect.
talcum powder
The bowl in the bottom of the primary fuel filter should be __________ so it can be visually checked for the presence of any water or solid contaminants on a periodic basis.
transparent (see-through)
An accumulation of soot (carbon) in a diesel engine's lubricating oil has a disproportionately negative effect on its _________ and _________.
viscosity and lubricity
An engine hour meter, or the use of engine time running log is the normal method for tracking of periodic maintenance requirements, however, a better indicator of service requirement intervals is the ______ __ ____ ______, so if it is possible to track that, particularly on electronically controlled engines that may have reviewable data logs, it is more accurate than engine hours.
volume of fuel burned
