Maintenance Tip of the Week: Vessel Use 12/21/2015

Maintenance Tip of the Week – Vessel Use 12/21/2015

So, you have religiously followed the maintenance schedule for your engines as outlined in your manual. Everything should be good, right? Not necessarily. You need to pay attention to how you use your boat. If you only use your vessel 25 hours per year, fuel deteriorates, condensation occurs, and corrosion keeps up its’ never ending march. This is why your maintenance schedule is often broken down into time periods of use, as well as calendar time.

Diesel engines perform best when they are started and used frequently. Always follow the storage procedures as detailed in your manual if the vessel will be sitting idle for long periods of time.

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.



Spring is coming. How to prepare your engine after winter storage.


Last fall, we wrote an article related to preparing your engine for winter storage. Since the Spring season is fast approaching, we have also detailed below the procedures for getting your engine reasy for the warm weather after storage all winter.

Procedures after winter storage

• Exhaust System

Remove all winter-storage-seals from exhaust and intake system.

• Electrical System

Reconnect the fully charged battery/batteries and tighten/lubricate the connectors. Check the condition of the serpentine drive system belt; replace if worn or dry.

• Cooling system

Recheck that all hoses and fittings in the raw-water system are connected and replace the impeller (be careful not to scuff the impeller, use grease). Prime the raw-water system to prevent overheating of the impeller at start-up.

• Air filter

Replace with new filter unit..

• Start-up

Starting procedure

Before starting the engine always check the oil and coolant level. Also inspect that no leaks on oil-, fuel- or cooling systems are evident.
1. Make sure gear is in neutral and that throttle is in idling position.

2. Turn ignition key to the ON position and wait for glow light to stop. This allows the automatic glow system to glow it’s first sequence.

Warning: DO NOT USE STARTING AIDS SUCH AS STARTING GAS; ETHER OR OTHER. (this will void any warranty.)

3. Turn the ignition key to the CRANK position to start the engine. If the engine doesn’t
start in 15 seconds, wait for 30 seconds and go back to step 2. As soon as the engine starts, let it run at idle while checking oil pressure and volt reading. It’s not unusual with smoke from the exhaust system just after start-up but this will stop once the engine reaches operating temperature. Glow system will automatically afterglow. Recommended cruising rpm for all Marinediesel engines is 2700-3200rpm although the maximum rated effect is at a higher rpm. It is necessary to choose a propeller that will allow the engine to reach maximum engine rpm at WOT to not inflict unnecessary load on the engine, which could effect longevity and void warranty. Do not exceed maximum recommended engine rpm as the pump reduces the amount of injected diesel after this rpm and engine power drops quickly.

Check for leakage of oil, fuel and water. Also check the oil level on the dipstick, if necessary fill up with oil. Let the engine idle up to operating temperature before usage or shutdown. When the operating temperature is achieved, again check for leaking fluids. It is always good to mix approx 1% two-stroke oil into the fuel tank once a year to give the fuel system added lubrication.



Winter Engine Storage



Today marks the first day of Autumn, at least for our customers in the Northern Hemisphere, and thought should be given to winter storage if you will not be using your MarineDiesel engines through the winter months. Since diesel engines require periodic starting in order to operate efficiently and without problems, long periods of disuse during the winter months can be problematic.

Below is our list of winter storage procedures for your reference:

Winter storage
• Oil system

Drain the oil from the engine, either by removing the oil plug in the oil pan or by a suction tube down the dipstick tube; remember it’s always recommended to do this when the engine is at operating temperature. Tighten the plug, clean the oil dipstick and reinsert it in the tube.

Then remove the oil filter and replace it with a new unit (don’t forget to prelubricate the seal ring on the filter and prefill the filter with oil) tighten hard with manual power. Refill the engine with new oil according to technical maintenance specifications. Check the oil level on the dipstick and if necessary add more oil to reach the correct oil level. Start the engine and run it for a few minutes so that the new oil can lubricate all moving parts. Turn off the engine and recheck the oil level on the dipstick, again add more oil if necessary.
• Fuel system

Check all hoses, clamps and fittings for leakage and wear, replace if necessary. Make sure the fuel tank is full to prevent water contamination. Add “water repellent” isopropanol to the fuel system. Remove and replace the fuel filter (remember to prefill the filter with fuel as you otherwise will have issues with bleeding all the trapped air from the fuel system).

• Cooling – system

Start the engine and run antifreeze mix through the raw water system. Check the freeze protection of antifreeze in the freshwater cooling system. If you need to add antifreeze make sure you allow the engine to run up to operating temperature allowing the thermostat to open and mix the added antifreeze. Never use more than 50% antifreeze. Turn off the engine and drain the raw-water system. At the same time remove the impeller from the impeller pump. Check all hoses, clamps and fittings for wear and leakage, replace if necessary. The heat exchanger, intercooler and oil cooler are exposed to raw water and should be inspected for corrosion that could lead to engine failure. It is recommended that the raw-water cooling system be cleaned and flushed every 500 hours or at least every two years.
• Exhaust system

When the winter service is completed make sure all exhaust outlets and the air filter are sealed to prevent moist/salt air from entering the engine.
• Electrical System

Remove and clean the battery/batteries. Also clean the battery cables and connecting poles. Store battery in a cold/dry environment (never below 0C/32F) and keep it fully charged.




Ask Professor Diesel – 05/26/2014


This week’s question comes from John in the USA:


Professor Diesel:

I know that diesel engines can run on many types of fuel, what would happen if I try and use gasoline?



NEVER use gasoline in a diesel engine. At best, permanent damage will result. At worst, explosion or fire. Some diesel operators will add a little gasoline to diesel when preparing for storage over extended periods, as this can help in starting (MarineDiesel does not recommend this practice and it will void your warranty if you try it). NEVER more than 10% of total volume. The engine will run, but it is safest to drain the fuel and lines if gasoline has been added.


If you have a question for Professor Diesel that you would like answered, please fill in the form below:

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Ask Professor Diesel 05/19/2014 –


This week’s question comes from Marten in the Netherlands:


Professor Diesel:

I have two VGT engines mounted in a boat that has been sitting in a shed for over one year. What should I do to prevent damage the next time I use the boat.



Diesel engines can incur a lot of damage when they sit idle for long periods of time. Ideally, you should start engines at minimum, once per month, or follow the extended storage procedure documented in your manual. Oil collects in the crankcase and becomes sludge, water condensation forms in fuel tanks and fuel lines, dust can get into various parts of the engine, and corrosion can start and get worse if the engine is not periodically inspected. Diesel fuel also quickly degrades over time. Assuming that the manual storage procedures were not followed, what should you do?


  1. Drain all fuel from the lines and tank, oil from the engine, and any fluid remaining in the water intakes.
  2. Inspect all hoses, connections, and fuel lines.
  3. Inspect the belts.
  4. If sludge has developed in the engine or crankcase, it must be removed.
  5. The fuel injectors must be checked and replaced if necessary.
  6. Change oil, fuel, and air filters.
  7. Clean the supercharger.
  8. Add water repellent to the fuel.
  9. Clean and flush the cooling system.
  10. Replace the impeller.
  11. Make certain that the batteries are fully charged and that connections are tight and corrosion free.
  12. Use the startup procedure described in your manual, just like with a new engine.


All of the above procedures must be done in accordance with the manual. If excessive sludge has built up, a rebuild or complete overhaul may be necessary.


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

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