Maintenance Tip of the Week – Battery Cables 11/09/2015
Battery cables are flexible. Periodically check your cables by flexing them. If your cables are defective, you should hear a crackling sound when flexed, in which case, replace them.
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.
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:
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?
- Refer to your manual. Marinediesel always lists the torque for bolt tightening in the manual.
- 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.
- 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.
Outboard engines are usually a complete waste of money for commercial and government vessels.
Quite simply, they are not designed for anything other than recreational, or occasionally, racing use.
Outboard engines are usually merely petrol car engines turned vertically and connected to a modified automobile transmission. They were designed to provide the torque that an automobile requires in order to operate efficiently. The problems start to arise with respect to torque: Boats are under far higher levels of resistance than automobiles, particular at lower rpm ranges. So, many companies have tried to use diesel engines in outboards, rather than gasoline engines. What was the problem? Simple. The gearbox and drive systems were not designed to withstand the amount of torque produced by a diesel.
There is an old saying in the marine industry: “Horsepower sells boats, but torque actually moves them”. A quick glance at the marketing materials produced by outboard manufacturers quickly confirms that fact: Virtually none of them mention torque or show torque curves.
Some advantages of a diesel inboard over gasoline outboards:
- Diesel fuel is normally cheaper than gasoline in most markets. For example, in Australia, August 2015, retail price of diesel is A$1.29 per liter average, petrol A$1.34. In some countries the differential exceeds 20%. For instance, during the same period in Thailand, diesel averaged US$0.64 per liter and petrol US$0.93.
- Diesel engines always consume less fuel than gasoline engines. For instance, a Mercury Verado 350 consumes a whopping 353 g/kWh at full throttle, compared to 221 g/kWh on the Marinediesel VGT300. This equates to over 1/3 higher consumption. At cruising speed of 5,000 rpm on the outboard, the fuel consumption drops to 190 g/kWh, but the power produced decreases by over 1/3, netting just over 220 hp. The VGT300’s cruising speed of 2,800 rpm yields a fuel consumption of 195 g/kWh, but still producing nearly 280 hp.
- As far as torque is concerned, virtually no comparison is possible. The outboard produces barely 400 Nm of torque, under a drastic bell curve, whereas the VGT 300 produces nearly 600 Nm of torque along the majority of the rpm range. A huge difference in actual work performed by the engine.
- Gasoline outboards have a MTBO of under 400 hours, light recreational use (all of them). A diesel inboard will last up to 3,000 hours MTBO. You could overhaul an outboard five times before needing to overhaul the diesel.
- The outboards are lighter. 303 kg versus 515 kg. This is reflected in their lower torque produced.
- However, space is less of a constraint. The Mercury Verado 350 is less than 100 mm smaller on all dimensions. A quick look at the photo above shows a transom width of about 1 meter. The VGT engines will require approximately 300 mm more length, and no extra width. A mere 300 mm extra height is necessary. In other words, on the boat picture, two VGT engines WILL fit.
- Outboards cost less to purchase. MSRP on the Mercury Verado 350 was US$32,000 in August 2015. The VGT 350 MSRP was US$37,000. However, given the fuel cost and consumption differentials, this small difference in acquisition cost quickly disappears.
- Gasoline is far more explosive than diesel. The inboards are much safer.
- Diesel engines have higher maintenance costs, but require much less maintenance.
As is evident in the points above, a strong case can be made for equipping your vessel with the Marinediesel VGT Series instead of outboards. The cost differential at acquisition is minimal, and the diesels far outperform outboards in nearly every instance. In particular, on the higher horsepower outboards, the price differential starts becoming significantly less.
Finally, in the picture above, twin Yamaha 200 hp outboards are pictured. A single VGT 400 or VGT 450 will outperform those two engines, lessening the price differential, even after gearboxes and drives are taken into account on the VGT engines.
Maintenance Tip of the Week – Fuel Filters 11/02/2015
Always use the correct size of fuel filter, as specified in your manual (most Marinediesel engines require 10 micron size). Incorrect, or cheap, fuel filters can seriously damage your engine, especially in locations where fuel quality is a problem. Inexpensive fuel filters are often of poor quality and are usually not much cheaper than quality brands.
Marinediesel are seldom the cheapest engines in our class in the market. Indeed, we usually are priced somewhere in the middle: Not the cheapest, and not the most expensive, either. We do, however, feel that we give our customers much more value for their money, due to our technical advantages:
- Highest power to weight ratio: More power for the same money.
- Longest life cycle: Our competition cannot even come close.
- Lowest noise and vibration: The Laws of Physics mean that we will be quieter, with less vibration than any of our inline six cylinder competition.
- Remote diagnostic capability: Our technicians can diagnose your engine, anywhere in the world from our factory in Sweden.
- Customized performance: Go ahead. Ask Yanmar to customize an engine and get back to us on that.
These advantages make a solid case for Marinediesel well above any minor price differentials. However, we ask you to take a look at the web sites of any diesel engine manufacturers.
How many list prices online?
There are very good reasons for this.
- There is nearly always a distributor involved for all but the most customized engine (like racing engines, which are manufactured annually in the dozens, rather than thousands or tens of thousands). Distributor involvement is an absolute necessity from a service perspective and for spare parts.
- VERY few people simply purchase a bobtail engine. Most engines require a certain amount of ancillary equipment in order to be installed. Simply comparing bobtail prices is inaccurate and pretty much useless.
- Volume. It costs less to supply 100 engines than two engines.
This last point is pretty important. When you equip a fleet of vehicles with a specific engine, it is normally much cheaper than simply equipping one or two vessels. It costs Marinediesel, as the manufacturer, less to make the engines, and we pass those savings on to our customer. This is why bulk purchases are usually much cheaper on a quantity basis. It really is not much different than when one buys food at the supermarket. Big, family sizes, of products are usually cheaper than individual portion sizes.
On your next project, contact your local Marinediesel distributor for a quote. Our distributors often have a great deal of price flexibility and we will work with them to provide you the highest performance possible at the lowest price possible.
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.
Thinking back to the old business school days, one of the first things that is taught in marketing classes is the use of “spin” in getting one’s message across to the consumer.
What is spin?
According to Merriam Webster: a certain way of describing or talking about something that is meant to influence other people’s opinion of it.
Or, to put it more bluntly, a form of propaganda.
Here in the Marinediesel marketing department, we are always exposed to different levels of “spin” put out into the marketplace. Indeed, as an engine consumer, spin can be confusing, and is, by nature, misleading.
One of the most common areas to encounter spin in the diesel engine market is with regard to engine ratings. Though it may surprise you, there is very little regulation in determining the actual meaning of engine ratings. In fact, as an engine manufacturer, we (or any other manufacturer) are not required to define terms like “light duty”, “heavy duty”, or “continuous duty”. We are only required to tell you the true output of the engines based on measured and tested power and torque, at specific rpm levels.
Therefore, the engine ratings game becomes an area that is often deliberately confused by engine makers, to their advantage, of course. To illustrate, Marinediesel’s definition of “light” duty might be something like “under 700 hours of operation at 80% WOT (wide Open Throttle)”, and another manufacturer might define “light” duty as “under 500 hours of operation at 50% WOT”. Are these definitions a lie? No. They are the parameters that the manufacturer establishes, and as long as they are consistent, they are valid. Are they spin? Most definitely.
This is how some engine makers are able to sell engines that are designed for recreational use to commercial, government, or military customers. The “heavy use” or “continuous use” ratings are, effectively, whatever the maker designates them to be.
Here at Marinediesel, we believe in being 100% open and honest about the capabilities of the engines we manufacture. This is why we often ask quite a few questions when we quote an engine. We would rather make certain that an engine is appropriate for its intended use than to sell something that is not a good fit. No marketing games with Marinediesel.
It becomes critically important that you, as the consumer, actually take the time to read and understand what the engine ratings advertised actually mean. If you need truly continuous duty, then let us know that you need continuous duty. If our engines are a match, or can be modified, we will give you a 100% honest answer.