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.

Safety Equipment Checklist for Boats

Safety Equipment Checklist for Boats   Liferaft line attached The liferaft will not work unless the trigger line is...

Top 5 Reasons Why an Inflatable SUP Should Be Your Next Yacht Accessory

In this article, inflatable paddle board expert Jason Paul gives the top 5 reasons why an inflatable SUP should be your next...

First Aid Afloat – jellyfish stings

  Wherever you are boating in the world I am sure you will be using a pilot guide to aid your navigation. Often in the...

Rudders and steering systems – Part 3

In the third of our three blog articles on rudders and steering systems, we look at how to replace rudder bearings and repair a water-saturated core.

Boat batteries

Under-sized battery banks are one of the key factors behind power failure at sea, as well as the premature failure of batteries, so make sure that your boat battery measures up to the use you want to put it to.

Wooden Hulls – Part 1

Traditional wooden boats have a plank on frame construction, a centuries old boat building method that is still in use today. Variations of the traditional method include carvel, clinker and strip planking, which all relate to the way the planking is attached to the frame.

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...

Competent crew skills: arriving and leaving a berth

Skilled boat handling is needed when entering or leaving harbour. Crew tasks include preparing the mooring lines and fenders...

How to ensure your boat is in proper working condition

In this article Eva Tucker from Volvo Penta presents a handy check list of all the things that you need to check regularly in order to make sure that your boat is in a seaworthy condition. Including maintenance, safety gear and electrical checks.

Boat decks and superstructure

The deck of a boat is constantly exposed to the elements and should be inspected on an annual basis. Particular attention needs to be given to the overall condition of deck fittings such as the stanchions, cleats and chainplates.

Galvanic and electrolytic corrosion

Galvanic corrosion is an electrochemical reaction between two or more different metals, in the presence of an electrolyte (note salt water is a good electrolyte).

Boating Rules of the Road – International ColRegs

    International ColRegs Rule 7: Risk of Collision Anyone who is responsible for a vessel at sea, from the...

Sailing & Motoring in Fog

Sailing & Motoring in Fog You can only measure the visibility accurately if sailing & motoring in fog when you have...

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...

Capsize – understanding the risks

A skipper should know how their boat will cope with rough seas. By working within known limits and understanding the risks,...

The give-way hierarchy at sea – who gives way to whom?

Whatever their size or type, all skippers have a responsibility to avoid collisions with other boats at sea.  It is...

Wooden Hulls – Part 2

It is important to ensure the essential hull maintenance of a wooden boat is done, even if you are paying others to look after your boat for you. The priority is to prevent rot from taking hold. The protective layers of paint and varnish over wood are far more critical than on GRP boats, where the topsides are painted more for cosmetic reasons.

A five day sailing cruise of the Solent, UK

Welcome to our virtual Solent sailing cruise – a five day sail in the south of England from Bosham Quay in Chichester...

Safety Briefings – leave nothing to chance

Before giving your crew a safety briefing, it is worth considering the specific circumstances of the planned trip, the...

Essential Boat Spares for Safety

  Boats Spares Tool kit What you carry in the boats tool kit will be useful for many boat repairs, but you might want...

Sail boat rig checks – Part 2

In part two of Sail boat rig checks we run through some useful rig maintenance tips and then finish with a brief look at what a professional rig check involves.

Seized fixings and fastenings

Maintaining a boat can be a rewarding experience but at times it can also be frustrating. A prime example of this is when you come across a seized fixing or fastening that refuses to budge. Read our tips on how to release and fix them:

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...

Boat engine basics

Boat engines come in all shapes and sizes and include inboards, outboards, petrol, diesel, electric and hybrid systems. Some engines are...

Sterndrive maintenance

Sterndrives are a popular form of propulsion in the powerboat market, but require a fair amount of care and maintenance. The main factors to be aware of are salt water corrosion, lubrication and regular inspection of the bellows, the condition of which is vital to prevent water from entering into the hull.