Maintenance Tip of the Week: Vibration 11/16/2015

Maintenance Tip of the Week – Vibration 11/16/2015

Vibration is a leading indicator of engine, gearbox, shaft, and propeller problems. If, while underway, you feel an increase in vibration, or unusual vibration, the propulsion system must be inspected immediately as soon as it is safe to do so. Continued operation with damaged propellers or shafts will quickly ruin your gearbox and damage your engine (This type of repair is also usually very expensive).

Maintenance Tip of the Week: Mounts 05/11/2015



Maintenance Tip of the Week – Engine Mounts

Engines vibrate considerably when operating, and bolts on the mounts can sometimes work themselves loose. Periodically re-torque the mount bolts to ensure that they are properly tightened.




Maintenance Tip of the Week – Propellers 02/02/2015



Maintenance Tip of the Week – Propellers

In the event of propeller damage, only operate as long as it takes to get to a place where you can safely make repairs. Damaged propellers or bent shafts create high levels of vibration that can quickly destroy gearboxes, couplings, and engines.







Vibration? Not with MD. Watch the video!



Vibration is a critical factor when choosing an engine. MarineDiesel’s V-8 VGT Series of marine engines produce such limited vibration, our competition can never hope to match our performance with their inline six cylinder engines.

Don’t believe us?

Watch the video below and see for yourself! You cannot balance a coin on any other engine!


5 Reasons to Re-Power your Boat



Engines lose performance as they age. Either from heavy use, environmental conditions, or even through the lack of use. Cylinders can become grooved, seals and gaskets become worn, and the engine is no longer providing the performance it once gave. This situation is not only with marine engines. Though marine engines operate under much harsher conditions than industrial engines or engines in land vehicles, those engines eventually also wear out and need replacement. This article is not so much related to replacing worn out engines. The rebuild versus re-power argument usually comes down to cost, and sometimes feasibility (Engines can only be rebuilt so many times).

What if you have an engine that is still functioning? Are there reasons to consider re-powering before the end of that life cycle?


Here are five reasons:

  1. Fuel Efficiency: We were recently involved in a project that was asking us to perform a cost / benefit analysis on re-powering some vehicles equipped with some old Cummins engines. Though these engines still operated, and were quite fuel efficient when they were manufactured (around 1990), re-powering with modern, MarineDiesel engines could save the customer almost 20% in fuel savings over the course of one year. Technology changes, and engines have become far more efficient in the last 20 years. Even though rebuilding the existing engines would be cheaper, the fuel savings over the long term more than make up for the additional acquisition cost.
  2. Emissions:  Emissions regulations have become extremely strict, especially in North America, Europe, and the Polar regions. Old engines were manufactured under different emissions regulations. What was once compliant is now non-compliant.
  3. Performance: As engine efficiency has increased, engines are now lighter and more powerful than ever. New engines nearly always show increases in vessel performance over rebuilt old engines.
  4. Vibration and Noise: As engines wear, they tend to vibrate more, offering a reduced life cycle over time. Additionally, the standards for vibration and, particularly, noise have changed over time. Modern engines are far quieter and produce less vibration than rebuilt engines.
  5. Cost of Maintenance: Every time an engine is rebuilt, a little of the life cycle goes with it. Though engines can be rebuilt to a very high degree of competence, they are still older engines with a significant level of use. Maintenance expenses will always increase. Perhaps not by much, but they will increase nonetheless. Add in the fact that, on average, the cost of rebuilding an engine averages 60% of its’ cost new. Extra maintenance expenses can quickly close the gap between new / rebuilt.








Engine noise is often one of the most critical criteria demanded by MarineDiesel customers. With military or government users, reduced noise is often essential to the successful completion of missions. On commercial or recreational projects, noise has an enormous impact on passenger or crew comfort, and is often regulated in some areas. Few things can be as irritating as being stuck on a boat with a noisy engine.

All engines produce noise to some degree. It is the level of noise that is critical.

Silencing equipment, vibration, engine mount type and quality, insulation, combustion, and the length and type of exhaust all impact noise levels. Vessel speed and sea state have an impact. Indeed, even the material of vessel construction has an effect, since metallic hulls produce more noise than resin or grp hulls.

Controlling noise starts with the engine. Reducing vibration will always result in lower noise levels. Using the proper engine mounts goes a long way towards controlling noise. At MarineDiesel, we have the facilities that allow us to test and control noise by duplicating real-world conditions. We often will test multiple silencers, engine mounts, or exhaust layouts exactly as they will be constructed on-site. This allows us to make changes to not only the type of equipment, but to the engine itself that can mitigate excessive noise.

This engineering goes beyond simply using one brand of silencer over another. In fact, we can let the customer know exactly how the noise can be controlled.

We have designed engines and exhaust systems that produce under 50 dB of noise at 2 meters. This is impressive by any standard.

This service and capability is one thing that sets MarineDiesel apart from our competition.

This engineering and quiet operation is one of the first things that our customers tell us when they sea trial. MarineDiesel manufactures one of the quietest engines in the market.


Maintenance Tip of the Week – ECU 09/08/2014

Maintenance Tip of the Week – 09/08/2014

The engine’s ECU can misinterpret excessive torsional vibration as an engine misfire, and this condition is commonly associated with excessive wear on the coupling bolts, flywheel bolts, or the engine mounts. These connectors should all be inspected thoroughly and replaced.


Maintenance Tip of the Week – Vibration 06/16/2014


Maintenance Tip of the Week



If vibration noticeably increases and persists, one of the first things to check should be the condition of the engine mounts. Worn mounts should be replaced.

Ask Professor Diesel 04/28/2014 – Engine Noise


This week’s question comes from Ibrahim in Indonesia about engine noise

Dear Professor Diesel:

We installed your MD170 engines two years ago, and they have been working great. However, recently, they seem to be very noisy. Is this normal? Are there ways to correct the problem?


Engines can get noisier over time, especially with heavy use. The reasons why can come from a variety of sources:

  1. Vibration over time loosens bolts, fasteners, and belts
  2. Fuel and oil filters have not been changed according to the schedule listed in your manual, or you have been operating with dirty fuel
  3. The engines are using the wrong fuel
  4. Oil has not been changed
  5. The engine timing is off
  6. The injectors are dirty

With the limited information you provided, it sounds as if your engine is ready for overhaul. How long has it been since this was done? If the engine was recently overhauled and mechanical causes can be eliminated, a variety of noise reducing methods are available, such as:

  1. Insulating the exhaust.
  2. Adding silencers.
  3. Changing the exhaust configuration.


If you have a question you would like to ask Professor Diesel, simply fill in the form below:


[accua-form fid=”9″]




Price matters, but here are five other, more important, considerations



When choosing between two engine types, there is much more to consider other than acquisition cost. MarineDiesel charges what we believe is a fair price for our engines… We are not the most expensive in our category, but we are also not the cheapest. If you are choosing an engine based purely on price, you will normally find cheaper products on the market. Indeed, as a company, we never make the cheapest price claim.

So what makes our engines worth a slightly higher price than some of our competitors?

Firstly, our marine line of engines are all V-8 engines, whereas nearly all competing products are normally inline 6-cylinder engines. The reason this is important is that V-8 engines produce far less torsional vibration than an inline four or six cylinder engine. Vibration impacts not only passenger comfort in a vessel, but also noise, and especially life cycle and Mean Time Between Failures (MTBF). The torsional forces produced by an inline engine greatly reduce the life cycle of that engine, and greatly increase the likelihood of catastrophic crankshaft failure. In a military or police vessel, this type of failure is highly problematic, and, for this reason alone, anything other than a V-configured engine should not even be considered. For more technical details of this issue, please download our brief white paper about Torsional Vibration.

Next, MarineDiesel engines are rated for heavy government, or commercial, use. Our competitors generally produce engines rated for recreational use. There is nothing wrong with that, but this means that such engines are generally not suited for operation under heavy use, exceeding 3,000 hours per year in some locations, and in the extreme climate conditions often found in such regions.

Derating. Though discussed previously on this site, most competing engine models are rated based on the climate where they are manufactured (normally in cooler, temperate zones). When operated in extreme conditions, these engines typically experience a power loss due to less efficient cooling from hot air and warm water. On some competitor engine models, this loss can be quite severe, sometimes approaching 50 bhp on a 500 bhp engine. For intermittent, recreational use, this may not present too much of a problem. With heavy commercial use, or mission-critical military use, the impact of this condition can be quite noticeable. Therefore, in order to obtain the engine performance and life cycle that government use requires, a customer may need to purchase higher horsepower engines to compensate for this power loss. Paying for a 50 bhp differential can easily erase any minor cost savings received. With MarineDiesel engines, all are rated for extreme conditions: In other words, under most conditions, when you pay for 500 hp, you receive 500 hp.

Programmable ECU. MarineDiesel is unique among engine maker in that we allow user programming of the engine’s ECU. Though several other manufacturers use this access to allow their dealers to make detailed diagnostic service in the field (as do we… The software is easily installed on a laptop and connected to the engine via a cable), none offer customization of the ECU. Why would we do this? The answer is simple. Many engines are used in vessels with unique missions and requirements. For example, most commando boats require very quick acceleration and rapid crash stop performance. By programming the ECU, we can “shift” the torque curve to a custom level, giving the vessel unique performance characteristics necessary to complete its’ mission.

MarineDiesel engines are built by hand, and extensively tested before they ever leave the factory. Engines are our ONLY business. Not construction equipment. Not trucks. Engines only. This level of quality control is impossible at larger manufacturers for whom engine sales may only represent a tiny fraction of their business.