Select Page

The regular maintenance of a marine diesel is key to preventing engine failure at sea. This means doing regular checks of the fuel, cooling, electrical and oil systems. The oil system needs daily checks of the engine oil level and additional checks for oil leaks.  It is also important to follow the manufacturer’s recommendations for changing the oil and replacing the engine oil filter.

Why is oil so important?

Most of us know that checking the oil regularly is a good idea and that oil reduces friction and wear of an engine’s moving parts, but engine oil does more than this. As it circulates, it helps cool the engine, it reduces corrosion and it also cleans the engine by removing carbon deposits and tiny metal particles. Failure to change the oil results in increased engine wear as all the carbon and metal particles build up, making the oil dirtier and dirtier.

While all that may make obvious sense, why is it necessary to change the oil when the boat is brought ashore for the winter? After all, the engine is not going to be used for several months. The reason for doing this is that old engine oil gets contaminated from the harmful by-products of combustion, making it very acidic. This corrodes the engine and shortens its life. Replacing the old oil with clean new oil will help to protect the engine.

Follow the manufacturer’s advice

It is also important to buy the grade of oil that is recommended by your engine manufacturer, so once again this is a case of consulting the manual for the correct type to use. This may prove to be more expensive than the average car engine oil, but when it comes to boat engines it is best to follow the manufacturer’s advice. This can be a particular problem for older engines where the specified oil is not widely available.

The recommended grade of oil for your engine will be given as an SAE (American Society of Automotive Engineers) grade. The SAE grade system refers to the viscosity or thickness of the oil where the higher the number the greater the viscosity, for example a SAE40 is thicker than a SAE30. A low viscosity oil such as 10W (“W” stands for winter) will flow better in low temperatures as it is thinner, meaning the engine will be easier to start and better protected in colder temperatures.

  

Today we have multigrade oils which are designed to work efficiently in winter and summer. For example a SAE15W/40 means that the oil is a multigrade oil with a viscosity of 15W when cold and a viscosity of SAE40 when hot. Multigrade oils have chemical additives which are mixed with the oil to change its characteristics at different temperatures.

It helps to check and learn the specific requirements for your engine and to keep a record of when you change the oil and filter. It also helps to keep a log of the engine hours and the manufacturer’s recommendations for oil changes – usually every 200 or 250 hours or so.

Oil leaks

If your engine has been leaking oil then it would be wise to check out what is causing the leak – either a failed gasket, a failed seal or worn piston rings. Some leaks are easier to deal with than others, so you will need to decide whether this calls for a professional repair or if it is something that you can do yourself. This very much depends on your engineering skills and experience.

The first thing to do is to wipe the engine and bilges clean and try to pinpoint where the leak is coming from, which is easier said than done in a cramped engine bay but rather easier when all round access to the engine is possible. Then check:

  • Head gasket – this is the biggest gasket and subject to very high pressure and temperatures. To replace this entails removing the cylinder head which can be done in situ.
  • Sump gasket – not as critical as the head gasket but this will require the engine to be removed for the repair.
  • Camshaft seals – the camshaft cover and pulley will need to be removed but the engine should not need lifting.
  • Crankshaft seals – the front crankshaft seal can be repaired fairly easily while the rear seal is more challenging as you have to remove the flywheel and gaining access is normally an issue.
  • Valve seals – replacing valves seals normally requires removing the camshaft.
  • Worn piston rings – oil leaking into the combustion chamber is caused by worn piston rings. The telltale sign of this is blue smoke coming out of the exhaust. This a major job which could entail a complete engine rebuild.

Dry friction

After a long period of disuse (over the winter for example), all the oil makes its way down into the sump. When the engine is started, the moving parts including the cams and bearings may have become completely dry and will be subject to dry friction, causing harmful metal abrasion. To overcome this problem at the beginning of the season, you can spray a small amount of oil into the air inlet and then turn the engine over without starting it. This will provide a coating of oil in the cylinders and reduce the friction.

Distress flares – which flare, how & when to use?

How to use distress flares at sea Flares should be kept in a waterproof container in an easily accessible location such as a...

Keel maintenance and repair – Part 1

Keels are designed to act as underwater foils that generate lift as the boat moves through the water, counteracting the leeward force of the wind and enabling the boat to sail closer to the wind. Keel maintenance and repair is essential for the performance of your boat.

Essential Boat Safety Briefing

Skippers Responsibilities Skippers are obliged to give a safety briefing to the crew even if they are a regular crew. At...

Sending distress signals

In an emergency situation at sea, it is a top priority is to know how to send and receive emergency radio calls and alert others of your predicament. Likewise, if you receive a distress signal, you must be ready to go to the help of others.

2023 Rolex Fastnet Race

Safe Skipper’s Simon Jollands took part in the 2023 Rolex Fastnet Race – a classic offshore sailing event. This is the first of several articles on the race and focuses on the start.

An explanation of the IALA maritime buoyage systems – IALA A and IALA B

What are the differences between the two IALA buoyage systems, IALA Region A and IALA Region B, and where are they used?   As recently as the 1970s...

Boat Engine Safety Checks

  Boat Engine Safety Checks Every skipper needs to make regular essential boat engine safety checks. Below you will...

Rewiring a boat – overcoming the challenges involved

Skippers need to have a basic knowledge of boat electrics, to avoid potential problems and to be able to solve them when they happen.

Common marine electrical problems

Most problems with marine electrical systems arise from four possible sources, a lack of maintenance, a poor standard of initial installation, insufficient battery capacity, or ineffective charging systems.
Water ingress is a frequent issue – salt water can corrode contacts very quickly. If connections are not scrupulously clean – or are loose – resistance will be increased, resulting in progressively reduced power.

Essential Knots: Sheet bend

Essential Knots: Sheet bend Use: Joining two ropes together. A sheet bend is particularly useful for joining two ropes of different...

Antifouling for leisure boats – Part 3

Antifouling is one of the least pleasant boat maintenance jobs to do, but it has to be done. The very worst job of all is removing the old antifouling as this can get seriously messy and is very hard work.

First aid at sea basics

At least one person on board should be trained in first aid and know how to administer the contents of the first aid kit, ensuring there are adequate supplies for the planned duration of the trip.

Boat engine fuel system

If engines are installed and serviced correctly then most marine engines are very reliable, but one of the most important parts of the engine to check and service is the fuel system.

Understanding tides

If you are used to sailing in tidal waters, you will know that tides can be both a benefit and a hindrance to the sailor. In many ways,...

Estimating and plotting your position at sea

This post covers how we go about estimating and plotting our position using traditional methods, when out of sight of land – covering Dead Reckoning, Estimated Position, Tidal Streams, Leeway and more…

Steel hull maintenance

A steel boat owner’s biggest enemy is corrosion. You don’t have to worry about osmosis or rotting timbers, instead rust is the number one issue that will keep you awake at night.

Antifouling for leisure boats – Part 2

To prepare for antifouling, as soon as your boat has been lifted out and pressure washed, you need to check all the surfaces of the hull below the waterline, remove any remaining barnacles and check for blisters.

Weather forecasting resources and tips

All competent sailors need to have a good basic understanding of how to interpret a weather forecast. They also need to be able to interpret the actual conditions they are experiencing.

Sailboat rig checks – Part 1

Sailing boat rigs need to be checked regularly to reduce the risk of rig failure at sea. In part one of Sail boat rig checks we run through a series of useful checks that owners and skippers can carry out.

Boat maintenance – what does it involve?

The maintenance of a boat involves things like cleaning, varnishing, painting, polishing, antifouling, servicing the engine, servicing the seacocks, and maintaining the gas and plumbing systems. It all amounts to a fairly considerable amount of work that can’t be ignored if you are to keep your boat in a safe and good condition.

Seacock maintenance

If seacocks are always left open and neglected they can eventually seize which will prove a serious threat to boat safety should a connecting hose fail and the seacock refuses to close. There are three main types of seacock – ball valves, cone valves and gate valves.

ColRegs when sailing single handed

  Don’t neglect the Colregs when sailing single handed Sailing single-handed represents several challenges for skippers, not least how to...

The dangers of running aground in a motor boat

The peril of grounding a motor boat is not only an inconvenience; it can lead to substantial risks for both the vessel and its passengers. . In this article, we’ll explore the potential dangers of running aground and highlight the importance of proper navigation and preparedness to avoid these hazards!

Boating emergency – how to broadcast a MAYDAY emergency call

How to broadcast a MAYDAY emergency call   How to broadcast a MAYDAY emergency call if a vessel or person is in grave...

Top Ten Tips For Learning The ColRegs Boating Rules Of The Road

Colregs Boating Rules Of The Road Skippers struggle to learn and remember the ColRegs Yachtmaster and Day Skipper course...