Maintenance Tip of the Week: Fuel Tank 01/04/2016

Maintenance Tip of the Week – Fuel Tanks 09/21/2015

Condensation can build up in fuel tanks very quickly. In order to reduce the likelihood of water contamination in your fuel, always operate your engines with the fuel tank as full as possible.

Maintenance Tip of the Week: White Smoke 12/14/2015

Maintenance Tip of the Week – White Smoke 12/14/2015

Smoke is always a leading indicator of engine problems, normally fuel or combustion related. With the current emissions standards that require compliance from Marinediesel, you should never see smoke coming from your exhaust. That said, what does white smoke indicate?

1. Bad fuel quality (most common)

2. Problems with combustion

As to bad fuel quality, the first step should be to check the filtration and see what is causing the problem. Fuel treatment or enhanced filtration may solve the issue.

Regarding combustion, there are many causes: Pump failure, air filtration or exhaust pressure issue, clogged injectors, changes made to the ECU, worn gaskets or damaged manifolds.

If the fuel quality is good, then the presence of white smoke indicates that major service is absolutely necessary.

Mass Spectrometer Testing



On marine engines, the most critical systems are: Fuel, Lubrication, and Cooling. A failure in any one of these systems can mean very expensive or complicated repairs to your engines. In this blog, we often write about the impact of bad fuel, and so on, but how can you know if fuel is the problem?

The answer should be familiar to anyone who has ever watched CSI or any of the crime shows on television: Mass Spectrometry. A lab will use a mass spectrometer to determine the chemical composition of your fuel, lube oil, coolant, or any other fluid on your vessel. Though most companies do not own these devices themselves, there are many labs that offer inexpensive analysis of your fuel or oil. Essentially, a sample of the fluid is taken, and the mass spectrometer provides a detailed report about what is in that fluid, whether it is rust, different metals, or seawater.

So, this should be the ultimate arbiter in the decision making process, right?

Not really. The results of the test are dependent on where and when the sample is taken. For instance, if you suspect you have bad fuel, you should not take the sample with fresh fuel just put into the tank. Likewise, with lube oil, the sample should be taken before oil is changed.

What is important to remember is that with the tools available to the marine industry today, operators can easily and inexpensively monitor their vessels for new or ongoing problems and prevent further damage.



Are there quality differences in diesel fuel?


Fuel quality is a topic that is frequently discussed on this blog. Fuel is such a critical factor in engine performance and reliability, that is why we give the topic so much attention.

Is there a difference between brands in terms of fuel quality? In other words, is there a difference between marine grade diesel produced by Shell, versus Exxon, versus any other brand?

The answer is, in theory, yes, but there are other factors that are far more important. The primary difference is the additives each producer blends with a specific brands of fuel. For instance, Exxon may add one proprietary additive to improve combustion and Shell may add their own proprietary blend.

The Cetane Number is also an indicator of fuel quality. The Cetane Number is an index of the time from injection to compression. High speed diesel engines typically perform better with higher Cetane Numbers, typically over 40.

What is far more important from an engine manufacturer’s perspective is the quality of fuel that the customer receives at the bunker. Fuel quality can vary widely based on storage conditions, infrastructure conditions, regions of the world or even within one region. These factors are often independent of brand, and out of the refineries’ control.

What is certain is the following: All major fuel producers in the world comply with strict ISO standards regarding fuel quality. When the fuel leaves the refinery, it is effectively guaranteed to be of a specific quality. Problems with quality normally arise much further down the supply chain.

All marine fuels are required to comply with the latest ISO 8217 standards, effective from June of 2012. Additionally, in regions where ULSD is mandated (most notably North America and Europe), sulfur content is further restricted and the fuel is in compliance with EPA and EU rules:

  • 15 ppm: Sulfur limit of 15 ppm (ULSD) becomes effective in June 2010 for nonroad fuel, and in June 2012 for locomotive and marine fuels. ULSD has been legislated for nonroad engines to enable advanced emission control systems for meeting the Tier 4 nonroad emission standards.

For the ISO quality standards, see the chart below:


DMX is the normal standard for marine use.



What happens if you put gasoline into a diesel engine?


Don’t do it.


Don’t try it.

At best, you will ruin your engine. Quickly.

At worst, you could start a fire.

Why would someone try this? There is normally no financial incentive, since gasoline, or petrol, is normally more expensive than diesel. When this situation happens, not too commonly with marine engines, in our experience it is a mistake when filling the tank. Somebody grabs the wrong hose.

But, you may ask, if diesel and gasoline both are distilled from petroleum, why is that a problem?

The answer lies in the way ignition of the fuel is made. Gasoline uses a spark ignition system that, when the fuel is mixed with air at the proper moment in time, combustion occurs.

On the other hand, diesel engines are based on the principles of self-ignition (there are no spark plugs). The heat from compression is what causes ignition, rather than a spark. When gasoline is introduced into the engine, it might ignite in the combustion chamber, it may not ignite, or it may ignite at the wrong time, possibly even within the exhaust system. The best case scenario? You have ignition at the wrong time in the cylinder, ruining the cylinder, piston, and cylinder head. Why is this bad? You have just introduced an explosion in a part of the engine that was never intended to contain an explosion.

Unfortunately, when such mistakes occur, there is normally very little recourse other than to drain the fuel system, and repair the engine, with a complete rebuilding usually required. That is, if you have not blown up the boat.


Adulterated Diesel Fuel



One of the biggest mechanical issues MarineDiesel encounters with our engines is poor fuel quality. Sometimes, this is unavoidable, and you simply receive a bad batch of fuel that has become contaminated, or has been sitting in a tank for too long.

However, a much more serious problem comes from adulterated fuel. This is often hard to detect, and vessel owners often have a difficult time proving where the fuel was adulterated.

Why do people tamper with fuel?

Three primary reasons:

  1. To cover up theft (replacing diesel that is stolen with other fluids).
  2. To circumvent emissions regulations. (Less-refined fuels are cheaper than diesel).
  3. To save money. (Fuel is an enormous portion of operating expenses. Though not wise, some operators still do this practice.)

Adulterated fuel does not burn cleanly. It also has a different caloric output than pure diesel. So, engine performance, at its’ most base level, will always suffer with adulterated fuel. The engine ECU is calibrated to use good quality fuel, and the engine compression is set to burn quality fuel.

The primary additive to diesel fuel that we encounter is Kerosene. Kerosene is petroleum-based, and your engines will burn it (this will void the warranty), however, if the percentage of Kerosene in a tank of fuel starts getting too high, serious damage to the injectors can result, translating into a very expensive repair. Why do people use Kerosene? It is much less refined than Ultra Low Sulfur Diesel, and therefore much cheaper. It also is usually taxed at a far lower rate than diesel, making it attractive for unscrupulous bunkers to add into fuel stocks. Unfortunately, in some countries this practice is extremely common, with percentages sometimes exceeding 60% Kerosene. Needless to say, any emissions compliance goes straight out of the door when these situations occur.

What else is often added?

One of the biggest messes is paraffin. Again, your engines will burn it, but as the fuel cools, paraffin solidifies, and has a tendency to clog the entire fuel system, resulting in a messy, and expensive, repair. We have also seen other liquids, including seawater, added to fuel tanks.

So, what can you do? Unfortunately, not much. Use bunkers who are trusted. Periodically have fuel samples checked for quality. Have crews monitor exhaust temperatures and check consumption rates versus fuel receipts. Keep fuel filters clean and change the elements when clogged, even if it is before scheduled service periods. Never tamper with fuel. Always check your engine manual to see a list of approved fuels.



Use it, or lose it


Time is not your friend when it comes to marine diesel engines. Diesel engines, by their nature, operate best when they are started frequently, and operated at WOT (wide open throttle) every once in a while. In a way, this is counter-intuitive, since diesels are often discussed in terms of life cycle, how long they will last before overhaul, and sheer number of hour used. However, a long time between overhauls does not mean much if the engines simply sit in storage or if the vessel spends most of its’ time tied up at a dock.

Diesel engines are complex pieces of machinery. Routine starting and operation keeps internal components lubed up and free from rust or deposits. Additionally, seals and gaskets take time to properly seal, and operating the engine makes good, tight seals. Additionally, diesel fuel degrades and becomes contaminated over time. Routinely starting and operating the engine keeps the fuel fresh, and fuel lines clear with periodic fuel flow. This is why MarineDiesel has a very specific winter storage procedure for owners to follow.

Commercial and government vessels typically have very heavy, continual use. Indeed, we have seen some of these vessel types operate up to 3,000 hours or more per year, under the harshest of conditions.

The problems associated with non-use are typically experienced on recreational, or pleasure, boats. They simply do not get the high use that commercial vessels. (Sometimes as little as 50 hours use per year). This is why it is important that pleasure boat owners start their engines, minimally, at least monthly, letting them run at WOT at least for a little while. If this procedure is followed, the engines should last as specified by their rating, giving years of reliable use.



Smaller Engines: Lighter, more powerful, and more efficient


Engine development and research is a constant, ongoing process. MarineDiesel tirelessly continues to research into ways to make our engines more efficient, more powerful, lighter, and cleaner than any of our competitors. We already manufacture the world’s lightest and most powerful marine engine in our class. But we will not stop there, resting on our laurels. No, we continue to try and always make our products better.

In the upcoming year, expect to see new and more innovative products from MarineDiesel. The following points highlight the direction that we believe the industry is headed:

  1. Engines will continue to get more powerful. Turbocharger research, and research into combustion mean that engines have progressively gotten much smaller over the last 20 years of our existence. We believe that trend will continue.
  2. Engines will become even more fuel efficient. We recently were involved in a repowering project, replacing some Cummins engines that were manufactured in the 1970’s. Our modern engines consumed over 45 g/kWh less fuel than the legacy engines (which were fuel efficient for their time). We are certain that this trend will continue.
  3. Diesel engines will become cleaner, as will diesel fuel. The emissions environment is continually changing. Regulations typically are updated to take effect years in the future. These ongoing trends are a certainty.
  4. Alternative fuel will continue to be a priority. We are already converting engines to LPG and CNG. We are researching other alternative fuel sources.
  5. Engines will continue to become smaller. We are looking at many different blocks, power ranges, and displacements for future engine models. Some are expected to be released before the end of this year.




Fuel in minus fuel out


Fuel monitoring is often a contentious issue when it comes to diesel engines. There are many ways to monitor consumption, some being accurate, while others not so much.

Diesel engines have a circular fuel flow system. Fuel is fed into the engine, part of that fuel is consumed (but not all of it), and the remaining fuel returns to the tank. This flow sequence continues until there is no more fuel remaining in the tank.

When MarineDiesel designs engines, we publish a fuel consumption graph that details how much fuel the engine consumes at different speeds. This consumption is determined by both testing and the use of mathematical formulas, under well-defined conditions. ISO standards are the defined conditions used (several are required), and we are required under EU law to adhere to these conditions.

So why is fuel consumption sometimes controversial?

The answer is simple. Under use, conditions change. All of the following impact fuel consumption:

  • Fuel quality
  • Fuel temperature
  • Air temperature
  • Water temperature
  • Fuel pressure
  • Exhaust pressure

Note that all of these variables can vary significantly from location to location. The fuel consumption figures we provide are based on static and defined conditions that rarely, if ever, are matched exactly in the real world. This is why we sometimes hear feedback from customers that their fuel consumption is more or less than advertised. This is why, on any online boating forum, there is always a lot of discussion on fuel use. Given the fact that fuel consumption is the biggest expense of operating any engine, small variations can have a big financial impact.

So, what is the “real” fuel consumption?

To start, we can give data that is best used as a starting point. What you can expect to see if you are in lab conditions. The variation in consumption could be as high as 10% or even more, depending on all of the criteria listed above and their variation from our test cell baseline.

The best way to determine actual consumption is by doing a combination of the following measurements:

  1. Tank levels. This is somewhat inaccurate, since tanks are usually odd-sized or odd-shaped. If the volume is known, the level is more useful.
  2. Metering. There are dozens of different meters in the market. Any that are well-calibrated will work, and some are more accurate than others. Monitoring the fuel in and fuel return flows, and calculating the difference is accurate. Fuel in minus fuel out equals consumption.
  3. Mathematically. There are various monitoring systems on the market that take sensor data and, using algorithms, calculate fuel consumption.
  4. Fuel receipts. Some commercial users use fuel receipts to determine consumption. This is not usually accurate unless there is ample historical data. For instance, a vessel was re-powered and the same operating patterns are present. We see this in small passenger ferries and water taxis where there are fixed routes and numbers of trips.

MarineDiesel, as a manufacturer, tries to bring the greatest value to our customers. Therefore, on all MarineDiesel engines, we have provided different data outputs using both or either  J-1939 and NMEA2000 protocols, so that customers may easily use most commercial fuel monitoring systems that are on the market.





1,768,000 Kilograms



1,768,000 Kilograms.

That weight is the equivalent of:

  1. 3 times the weight of Christ the Redeemer, the famous statue in Rio de Janeiro.
  2. 1/5 the weight of the Eiffel Tower.
  3. 11.5 times the weight of the average single family home.
  4. 17 times the weight of an adult blue whale.
  5. The weight of the CO2 produced by a MarineDiesel VGT350 engine over the course of its’ lifespan.

There is a lot of discussion in the media regarding CO2 as a greenhouse gas. CO2 is a product of the combustion process, and as such, is one of the emissions that cause environmental concern. Unfortunately, CO2 is extremely difficult to prevent or eliminate from emissions.


Diesel fuel is roughly comprised of 82.6% carbon. Since combustion requires air, oxygen is forced into the combustion chamber of the cylinder and it combines with carbon to form CO2.

CO2 is not regulated in the same manner as other emissions. Where required, carbon trading or other taxation schemes are used. However, this does not give engine makers a “free pass” regarding CO2. Efficiencies in turbocharging, electronic engine controls, and fuel efficiency also play a part in reducing carbon emissions. Scrubbing systems are becoming more compact and less expensive, and it will be several more years before the technology is applicable to smaller engines, but change will happen.

Given the fuel economy of Marinediesel’s VGT Series of engines, consumers are making a smaller carbon footprint by choosing the most efficient engine available in its’ class.