Wiring Color Coding

When you take a look at an engine, it can easily resemble a mass of wires and cables. However, one of the tools provided to assist in maintenance is the color coding of wiring. Wiring is standardized according to SAE regulations, of which Marinediesel is compliant. However, color codes between manufacturers may vary slightly from make to make.

Marine wiring is twisted pair, shielded, to minimize interference (EMF). It is required to be both oil resistant and able to withstand heat of at least 75° C.

There are a few minor differences between marine wiring and wiring intended for land vehicles, normally the fact that vessels require a higher gauge and extra moisture resistance due to their environment.

So, what are the color codes?

Marinediesel has numerous charts listing the color codes to specific engine components in our electrical manual, available for download.

Though there is some variation, as mentioned, between manufacturers, there are some general consistencies:

marine wire


What is J1939 protocol, and why should you care?

When looking at different engines, you may encounter the term J1939, and this term is important, but why?

J1939 is the proprietary name of the protocol used by engine manufacturers for vehicles. Much like spoken languages, such as Chinese or English, J1939 Protocol refers to the language that the engine “speaks”. The ECU of the engine takes the signals sent by the engine sensors and either makes adjustments (as in fuel to air mixture) or communicates that information, either to a display, or to a software program.

Much like language in humans requires listening and speaking, an engine protocol requires both receiving information and communicating that information. So, what is J1939. J1939 is the SAE standard that engine manufacturers typically use to ensure that the engine is in compliance with industry standards. Since the majority of marine engines are derived from automobile, truck, or other engines, this protocol is largely standard. Additionally, there are various ISO standards that are also required, often mandated by law. However, J1939 is not mandated. It has simply become the overall standard that most engine makers use.

Why is this? In short, nothing legally requires an engine maker to use the J1939 protocol, but should an engine maker not use J1939, they would face major problems with component compatibility (like ECUs), monitoring systems, and even from manufacturers of gauges. Additionally, since the maintenance shops at marinas, government, and commercial operators are equipped to deal with J1939, end user maintenance becomes much easier and cheaper when standards are in place. Does Marinediesel comply?

Like most manufacturers, Marinediesel uses J1939 in the programming on our ECU. J1939 is an incredibly flexible protocol, and there are differences between J1939 for off road and on road use. However, most engine monitoring systems should be able to communicate with our engines, not only with fault codes, but in monitoring performance. Additionally, aftermarket vessel systems that require engine data (such as fuel management systems) should be compatible with Marinediesel engines.

Cylinder head gasket damage: Is it the cause or a symptom?

The failure of the cylinder head gasket is often blamed for causing severe engine damage in marine engines. However, if gasket failure a cause of damage or is it merely an indication of other, more serious problems?

Gaskets are designed to seal. They either keep various matter inside of something or keep it out, whether gas, solid, or liquid. In the case of cylinder heads, gaskets deal with three different components, all related to combustion:

  • Oil
  • Water
  • Gas

If a gasket is properly installed, it should function as designed for a very long time. What are the indicators of gasket failure?

Namely, that the gasket is no longer sealing. The cylinder head gasket not only seals the cylinder from external factors, such as preventing water from getting inside the cylinder, but from between different cylinders on an engine (such as gas from one cylinder leaking into an adjacent cylinder. Obviously, such leakage interferes with the combustion process, and engine damage is the inevitable result.

So, what tells the operator that a gasket may be damaged?

  • Poor cold starting
  • Loss of power
  • All cylinders not firing
  • Different colored smoke
  • High water temperatures

All of these indicators mean that the cylinder head gasket may be damaged. So, you disassemble the engine and replace the gasket. The problem with this is that the gasket may not have been the cause of the failure, but rather a symptom of a different problem. Gasket failure can be caused by a number of different factors, including:

  • Improper torque on the cylinder head bolts
  • Rapid acceleration of the engine after cold start
  • Roughness on the cylinder wall
  • Uneven cylinder top
  • Loose cylinder liner
  • Compression incorrectly set in the ECU
  • Defective thermostat
  • Cooling system blockage or leak
  • Pump failure
  • Exhaust system back pressure caused by either leaks or blockages

How do you know that the gasket itself caused the failure?

  • Discoloration of the gasket (The area of discoloration usually shows the location of the leak, due to heat, whether caused by the gasket or something else.)
  • Excessive flexibility
  • Corrosion along the edges or eyeholes of the gasket
  • Rough surfaces on either the gasket or engine block

This last point is critical. Modern gaskets for marine use are designed of materials that are engineered to be resistant to corrosion and degradation. In most cases, if it is the gasket itself that has failed, rather than another part of the engine, it is usually the result of improper installation of the gasket. In particular, improper tightening of bolts and installation on dirty surfaces causes these issues. Why?

Simple. The gasket must seat properly and seal. Tightening bolts too tightly warps the gasket, preventing the seal. Dirt or liquid under the gasket prevents a proper seal. Since combustion produces heat, the problems are magnified as the heat becomes excessive, further speeding up failure of the gasket.

So, what can be done?

  1. Refer to your manual. Marinediesel always lists the torque for bolt tightening in the manual.
  2. Use only OEM Genuine Spare Parts. The gaskets we use are designed for the engine and made of materials intended to withstand their designed use.
  3. Realize that gasket failure may be a symptom, rather than a cause. If something is causing gasket failure and that cause is not corrected, the failures will continue.





Need to contact Marinediesel for technical assistance? We need your engine serial number.

Though we recently posted this question in our   Engine Maintenance FAQ, this subject is really important, so we will occasionally post reminders about it on the blog.

Why are we making a big deal out of the engine serial number?

Quite simply, because the engines are continually evolving and changing from one year to the next. As an example, there have been about ten versions of the Marinediesel VGT Series. As engines progress from idea, to development, to testing, to market introduction, to production, different components are either tweaked or changed based on field experience and feedback from our customers.

In a way, it is very similar to the updates that computer software publishers make as bugs are discovered. Indeed, given the electronic nature of the VGT Series and the use of the NIRA ECU, software updates are often one of the changes we make.

When an engine is manufactured, detailed production notes are kept about that specific engine during the production process. We know, for example, which turbocharger was equipped on the engine, what software version was installed, and custom configuration, etc.

Additionally, the engine serial number allows us to see any changes made to an engine, by Marinediesel, since that engine was sold. Indeed, we recently has a mechanical issue with a customer where there were changes made to the engine, and nobody (including our customer!) could remember what was specifically done to the engine. Our technical team having the serial number eliminates problems and issues like that.

So, before contacting Marinediesel with technical questions, you should look up the engine’s serial number first, so we can give you an accurate solution for your engine problem.


Location of engine serial number, VGT Series


Which Silencer Is Right for You?

Today’s article is a guest article submitted to us by Ron Burg of Mahan’s Thermal Products, experts and specialists in heat exchanger and silencer technology. It is a very good general overview of the choices in silencers, and we encourage you to visit their website. We hope you find it interesting:


No matter what industry it is or which application is being used, utilizing heat exchangers and other types of thermal products in your facility can make noise control an issue. Fortunately, there are many ways for you to cut down on sound attenuation in order to create a better work environment.


There are many different types and models of silencers. If you need assistance selecting a silencer, reach out to trusted professionals such as Mahan’s to help guide you through the process. Six main types of silencers are included below.

Absorptive Silencer: With its classic dissipative design, the absorptive silencer absorbs noise energy through its many types of fibrous packing materials. When sound waves travel through the areas between the fitted fibers, the noise is dissipated from the viscous friction. Absorptive silencers work well on high noise frequencies between 500 and 800 Hertz. Anything above or below this amount, and the silencer will not be as effective.

Blower Silencer: These types of silencers are frequently used in wastewater treatment facilities and industrial processing facilities. Blower installations are typically noisy, making blower silencers essential. When choosing a blower silencer, consider the size and proper type for the application. These two aspects are critical for effectively reducing noise. The size of the blower should be based on gas volume alone, while the design of the silencer must be chosen with the blower size and operating speed in mind.

Engine Exhaust Silencer: Exhaust silencers come in a variety of styles and configurations, and have different attenuation grades. While you can create custom engine silencers, there are also standard styles that you can choose from. Puck-style silencers and low-profile silencers are great for places with minimal vertical space. Puck-style silencers are shaped like a hockey puck. Low-profile silencers are shaped in a rectangular fashion and are best for engines with dual exhaust turbos spaced far apart. Because of their rounded side panels, low-profile silencers are excellent for acoustic performance. Puck and low-profile silencers can come in residential, critical, and hospital attenuation grades.

Industrial Fan Silencer: Many process plants and industries require air fans, force draft fans, and induced draft fans, and they usually need some sort of acoustical treatment to fit into OSHA requirements. There are silencers for all fan types, and many are cost-effective, thanks to computer-enhanced technology. The advantages of each type of fan silencer depends largely on the application, pressure drop, and how much space is available.

Vacuum Pump Silencer: These types of silencers are used to eliminate liquid from gas flow vacuum systems by using liquid ring vacuum pumps or rotary positive blowers. Vacuum pumps are usually loud and require a high-performance silencer.

Vent Silencer: Vent silencers are frequently seen in oil and gas facilities and also in chemical processing heat recovery systems. These systems usually require a pressure relief valve (PRV) and need a vent silencer to effectively silence high-velocity air, steam, and gas vents. Vent silencers can be easily customized to fit any system.



Since 1969, Mahan’s Thermal Products has strived to provide quality production and sale of heat transfer equipment. Mahan’s is dedicated to taking care of its customers at all times and values the long-term relationships it has established with dedicated clients. Whether you need cleaning, repair, or building services or are looking to purchase a superior product at a competitive price, Mahan’s can assist you with your thermal product needs.


VGT Series Break-in Procedures

When engines are new, they require certain break-in, or run-in, procedures before they are subjected to heavy use. The reason is that, though the engines are tested at the factory, seals and gaskets need both heat and time to form a good seal, and the engine needs time to properly lubricate. If proper break-in procedures are not followed, severe engine damage can result.

Below is the procedures for our VGT Series of engines.

The Marinediesel VGT series engines need break-in time before being operating to its full potential. This is due to the design characteristics of the base engine.

Follow the recommendations below:

0-5hrs: Use varied load and rpm but do not load the engine above 50% throttle and keep maximum rpm below 2500. Do not stay at one load and rpm configuration for more than 30 minutes at a time.

5-10hrs: Use varied load and rpm but do not load the engine above 60% throttle and keep maximum rpm below 2800. Do not stay at one load and rpm configuration for more than 30 minutes at a time. A few short WOT trials up to 3600 rpm is allowed for performance trials

Do an oil and filter change after the engine has run a total of 10hrs.

10-30hrs: Use varied load and rpm, the engine can be used up to 100% throttle and full rpm for shorter periods. Do not stay at one load and rpm configuration for more than 30 minutes at a time.

Do an oil and filter change after the engine has run a total of 50hrs.
Use oil and filter as specified in the engine technical manual.

If you have any questions regarding this break-in procedure please consult the technical department at Marinediesel in Sweden.



MarineDiesel Services Profile: Engine Installation and Commissioning


Today’s article continues our series profiling MarineDiesel’s various services.

Engine Installation and Commissioning

MarineDiesel understands that when we sell an engine, we often need to be the ones who install and commission that engine. Most commercial shipyards are perfectly competent to install an engine, yet, particularly on new projects, factory installation is desirable. It is also important to note that all MarineDiesel distributors are fully trained in engine installation and can perform these services locally.

One of the most critical tasks related to the reliability of  the entire propulsion system is the installation of engine and drive system. This can be performed by the operator, boat builder or the local Marinediesel representative, but it can also be performed by Marinediesel factory engineers on site anywhere in the world.
MarineDiesel factory engineers provide first grade quality service,  as well as reducing  the risk of breakdowns and stoppages related to poor installation. It can also allow for time to train local technicians on installations, thus, for the future, enhancing the skill and know-how level of the operator’s or boat builder’s own staff.
A professional installation  not only assures smooth  operation, but it also reduces operational  costs. In this context, prolonging engine  life  and  maintaining  operational efficiency are key objectives that are addressed by this program.
Marinediesel  can also supply a full project management service, supported  by expert personnel  and by a global back-up service. All this is targeted at the goal of providing the operator with complete confidence that the engines will run efficiently with excellent long term service.
Quality based , cost effective service delivered by factory engineers
Opportunity for the transfer of technology and know how.
Operational costs minimized due to reduced risk of breakdowns and stoppages related to poor installation
Expert project management
Peace of mind with full OEM warranty

The  quality workmanship of the propulsion system installation is verifìed and signed off during the commissioning. Our  fìeld  service  engineers  are  uniquely experienced   in commissioning engines,  and  will ensure  that  every aspect of their  performance is fully tested  and  optimized before handover. This includes auxiliary equipment such as transmissions  and drive systems in liaising with other suppliers when necessary to ensure that every part of the installation functions correctly. Commissioning can be performed by Marinediesel fìeld service  engineers  on  site  anywhere  in the world. The  commissioning sign-off is also required  for warranty to take effect.



MarineDiesel Services Profile: FACT Customer Training

Today’s article continues our series highlighting MarineDiesel’s services.

Training is one of the most important aspects of engine manufacturing that exists. If customers are not adequately trained in the maintenance and operation of our products, then they will not experience the full advantages and benefits MarineDiesel engines offer to them. We are the marine engine experts, and we view training as sharing our knowledge.

All MarineDiesel distributors are capable of providing FACT training on a local basis.

Skilled and trained local technicians and engineers are essential for any operations long term targets related to cost and performance. Marinediesels training service provide the means to improve skill and productivity of local employees while enhancing the performance of the engines by making them run longer, more efficiently and more reliably.

FACT training stands for Fuel, Air, Compression and Timing which once theoretically understood are the bases for all diesel engines performance as well as an essential tool for diagnostics. Marinediesel offers a wide range of training courses that can be tailored to specific customer requirements. There are several options available but the most commonly requested courses are the FACT level 1 and FACT level 2.

FACT Level 1 is a one week course targeted for technicians, engineers or operators who want to gain a better insight into diesel engine design and operation as well as service and maintenance. The course is divided 50/50 into theory based and hands-on work.

FACT Level 2 is a two week course targeted for technicians, engineers or operators wanting more detailed hands on instruction and practical participation. The course covers theory and practice for major maintenance work, overhaul procedures and trouble shooting techniques.

» Quality-based, cost effective training and know-how transfer
» In depth understanding of engine theory minimize problems and aid trouble-shooting
» Theory as well as hands on instructions
» Training at Marinediesel’s training centre in Sweden or at location anywhere in the world.
» Courses can be tailored to meet client specific requirements
» Reduced downtime through more skillful operation and maintenance.

Courses can include:
» Theory of the 4-stroke diesel engine
» Engine construction and overall design
» Specialty tools
» Identification and location of components
» Safety instructions
» Preventive maintenance
» Scheduled maintenance
» Engine overhaul
» Tolerances and clearances
» Mechanical diagnostics
» Electronic diagnostics
» General trouble shooting
» CAN based diagnostics software
» Fuel systems
» Cooling systems
» Boost systems

Contact your local MarineDiesel distributor today for complete details.




Who is NIRA?


MarineDiesel’s VGT Series of marine engines goes against the Bosch mold in the industry when it comes to the electronics and ECU with which the engine is equipped. Why?

The simple answer is that there are other control units on the market that are more adaptable, more reliable, and offer far more flexibility. We use a NIRA ECU with our VGT engines, and we do so because this ECU lets us “customize”, to customer requirements, the performance of the engine. We can program multiple engine MAPs into the ECU, and it allows an operator to change, via a switch, how the engine performs (ie: on a military boat, one MAP for patrol and a different MAP for boarding.

Who is NIRA?

NIRA is NIRA Dynamics AB, a Swedish company that specializes in monitoring and electronic control systems.

From the NIRA Website

A Swedish expert company focusing on innovative software solutions for vehicles

NIRA Dynamics was founded in 2001 and is located in Mjärdevi Science Park in Linköping, Sweden, from where we support customers and partners worldwide.


NIRA Dynamics is developing unique sensor fusion based systems for different vehicle applications that utilize the potential in the sensor fusion idea to improve the performance, reduce the system cost and at the same time, increase the customer value. Through close collaborations with world-class research groups at Linköpings universitet, Sweden, and Chalmers University of Technology, Sweden, NIRA Dynamics is constantly in touch with the research frontier in these and other areas where sensor fusion and other types of signal processing are employed.

Sensor Fusion

Sensor fusion, or sensor data fusion, can be described as using information from several different physical sensors to compute new, virtual sensor signals. The virtual sensors can in principle be of two different types:

  • Improved versions of physical sensor signals, or
  • So-called ‘soft sensors’ or virtual sensors that have no direct physical counterpart.

In both cases sensor fusion adds value, not cost.


By using technologically advanced components produced by companies such as NIRA, MarineDiesel ensures that our customers get the high levels of performance that they require.



Best of 2014 – Engine Room Ventilation



We wish all MarineDiesel customers a happy holiday season. Our factory will close from December 22 through January 5. For the balance of the year, we will be re-running our most popular articles from 2014, based on the number of visitors. We will start new daily articles in the New Year. We hope that you continue to find them interesting.

MarineDiesel designs its’engines with reliability and service life being key concerns. Using a Duramax block as a foundation for our VGT Series of engines, the product is reliable and trouble-free as long as regular maintenance is performed when due.

There are, however, two situations that can greatly reduce engine life. The first is the use of dirty fuel. The second is inadequate ventilation of the engine compartment.

This situation is most prevalent in tropical, or hot, climates.

All engines produce a tremendous amount of heat. That is how they operate and why they produce power. In order to operate continuously, they must be adequately cooled, with ample ventilation provided for continued operation.

This is where problems can arise. The VGT Series, in particular, being so compact, is often used in very small craft, such as RHIBs, that have very small engine compartments as part of their design. Small, tight, engine compartments tend to lack much ventilation, and therefore ventilation must be provided in order to ensure trouble free operation.

From MDS, our service team:

Engine power is affected by a number of different external factors. Among the most important are air pressure and volume, air temperature and exhaust backpressure. Deviations from the normal values affect engine performance, function and reliability.
Diesel engines require a large amount of air compared to petrol engines. Reductions from the required values show up first of all as an increase in exhaust black smoke. This can be particularly noticeable at the planing threshold when the engine torque demands are high. If the deviations from the required values are great, the engine will lose power. This power loss can
be so great that a planing boat cannot pass through the planing threshold. For the engine to function properly and give full power, it is absolutely essential that both the inlet and outlet air ducts are sufficiently dimensioned and installed correctly.

Two main conditions must be fulfilled.

1. The engine must get enough air (oxygen) to allow efficient combustion.
2. The engine room must be ventilated so that the temperature can be kept down to an acceptable level.

Ventilation is also important to keep the engine’s electrical equipment and fuel system temperature at an acceptable level and for general cooling of engine components.

Basic design.

Engine space ventilation should be considered at an early stage and well before the engine is installed as it is often has to be integrated into the boat structure. Guidelines for air intake area are provided in the installation data and we have provided basic formulae in this section if you wish to calculate your own. Air intake area should never be underspecified, it is always better to have too much than too little. Intake air should always be directed to the bottom of the space and exhausted at the highest part preferably on the opposite diagonal to promote good circulation and natural convection.

There are two schools of thought concerning engine space ventilation, that of the engine manufacturer and that of the boat builder. Most engine manufacturers recommend forcing air into the engine space to provide positive pressure to ensure adequate air supply and ventilation for the engine. Boat builders on the other hand tend to favour extracting air from the engine space to provide a small negative pressure, this can prevent engine odours and fumes entering the passenger compartment through cable and hose ducting, etc.
Either system can be used for MarineDiesel engines but we prefer forcing air into the engine space and having properly sealed engine rooms to prevent odours and fumes. If air is to be drawn out using a fan then we recommend adding the CFM of the fan to that of the engine when working out your air intake area.

Engine room depression.

The maximum engine room depression is 0.5 kPa at full speed, this should be checked in every circumstance irrespective of the type ventilation system used.

Dimension of air intakes and ducts.

The engine itself sucks in air very effectively and naturally will take in air from any direction. Should the inlet or outlet air ducts be under dimensioned, the engine will consequently suck air from both ducts and no ventilation air will go out through the outlet air ducts. This causes dangerously high engine room temperatures and potential engine damage. Most of the radiant heat from the engine must be transported out of the engine room. This is an absolute requirement to keep the engine room temperature below the permitted maximum limit.

Engine room temperature.

Remembering that the engine’s performance figures apply at a test temperature of +25°C, it is important that the inlet air temperature is kept as low as possible. The temperature of the inlet air at the air filters should not be higher than +25 °C for full power output.

There is always a loss of power with increased temperatures and if the engine’s inlet air is constantly above +45°C the engine ECM will de-rate the engine as a safety measure. During sea trials the air temperature in the air filter should not exceed 20 °C above ambient temperature or 45°C maximum.

Location of air ducts.

Air intakes should be located where there is a clean flow of air and away from low pressure zones of the boat structure. They should be designed in such a way as not to allow water ingress into the engine space and provide a dry air supply for the engine(s). Care should be exercised with multiple engine installations to ensure air is delivered effectively to all the engines. If louvers are used, the air inlets should be louvered forward and the air outlets louvered towards the stern, this will encourage ventilation on naturally vented systems. Blowers and/or extractors can also be incorporated if deemed necessary. The channels or ducts for the engine air supply should be routed up as close as possible to the air filters but with a minimum distance of 20–30 cm (8–12″) as a precaution should water enter them.

All channels and ducts must be routed so that the least possible flow resistance is obtained. The bends must not be sharp but softly rounded. The smallest radius should be equal to the internal area. Restrictions must always be avoided.
The ducts should be cut obliquely at the ends to assist flow.


Air intakes or outlet holes must never be installed in the transom. The air in this area is turbulent and usually a mix of water and exhaust fumes and must therefore never be allowed to enter the engine or boat.

Function of air intakes.

Air intakes and outlets must function well even in bad weather and must therefore have efficient water traps. Soundproofing must usually be built in. The air intake and outlet should be placed as far away from each other as possible so that a good
through-flow is obtained. If the intake and outlet are too close, the air can re circulate resulting in poor ventilation.

Engine’s air consumption.

The engine consumes a certain amount of air in the combustion process. This requires a minimum internal area of air supply ducting, the minimum area can be calculated by using this formula.

A = 1.9 × engine power output in Kw
A = Area in cm²

The area of the outlet ventilation ducting can be calculated to be a minimum of a third of the air intake ducting area. The value applies for non-restricted intake and up to 1m (3.3 ft) duct length with only one 90 degree bend. The bending radius should be at least twice the internal area. If longer ducts or more bends are used, the area is corrected by multiplying a coefficient from Table
1 below.

eng vent1

Ambient temperature.

The ambient air temperature, (outdoor air temperature) is assumed to be +30°C (86°F). Correction factors as per Table 2 below should be applied as required by multiplying the calculated area by the correction factor.

eng vent2

A - Air should exit the engine bay and the upper section B – Air should enter the engine bay at the lower section

A – Air should exit the engine bay and the upper section
B – Air should enter the engine bay at the lower section