Outboard Motor Maintenance

History - In the early 1900’s Cameroon Waterman, an American, designed an outboard motor based on the motorcycle engine, a few years later Ole Evinrude a Norwegian/American designed an outboard, the ‘Evinrude Outboard’ went on to be one of the most popular outboards in America and is marketed today as a global brand.

Modern Outboard Motors - Modern outboard motors are either 2 or 4 stroke, traditionally using a carburettor to supply fuel mix to the cylinder. To comply with new emission regulations, these models are being phased out for the cleaner and more efficient fuel injection systems.

Outboard Engine Maintenance - Imardex Marine has designed a comprehensive maintenance programme to be followed by owners of outboard motors. Requiring only basic skills, this maintenance programme covers all the mechanical work to keep the engine in a seaworthy condition. It does not include tasks where rebuilding is required. The programme is easy to use and access. The task schedules can be set to those periods alongside allocated for maintenance.

Installing the outboard motor - It is essential to check the outboard is correctly installed on the transom. An outboard motor too high out of the water means the propellor will slip and cavitate. An outboard motor too low could result in excess drag and the engine could be swamped by a following sea. Outboard motor tilt is also important, the wrong angle of tilt pushes the bow or stern down, this slows the boat and decreases fuel efficiency. As speed increases the correct angle can be checked by looking at the cavitation plate (located above the prop) on the outboard, it should align with the water.

Driving with an outboard - As you become more experienced at driving with an outboard it becomes second nature to set the correct tilt, speed and trim. These settings ensure guests and crew have an enjoyable ride. You should also learn to set economical cruising speeds that are adjusted to the sea state, this provides maximum comfort and fuel economy.

Propellers - Propellers can be designed to suit different jobs. For fishing and trolling, propellors require a lower pitch. For faster boats a higher pitch and for maximum efficiency a Duo Prop is essential.

Spark Plugs - Spark Plugs are one of the most important parts of an outboard. Carrying a spare set is essential. There is a degree of minimum maintenance necessary for the efficient running of the engine. Spark plugs should be removed and cleaned, the sparking gap checked and adjusted as required and a new gasket fitted on replacing the plug. Always remember after replacing to clean around the plug with a clean, dry cloth.

Galvanic & Stray Current Corrosion - Galvanic and stray current corrosion is one of the main threats to the life of an outboard motor. Galvanic corrosion is the electrochemical reaction between dissimilar metals. Stray current corrosion for example can be when a boat is connected to the shore power, it will flow through the boat, the outboard and then to ground through the water. There are many forms of stray currents that can affect a boat.

The salt-water environment - When the outboard is used in a saltwater environment, it is important to clean the engine inside and out with fresh water as soon as possible after finishing for the day. Also, check anodes are intact and in place. A good habit is to periodically inspect the outboard for white powdering around connections and blistering paintwork, indicating signs of galvanic corrosion.

Safety – Kill Cord - When the boat is underway, and for the safety of the crew and passengers, the helmsman must always be attached to the boat with the kill cord. If the helmsman falls out of the boat and the kill cord is attached, the engine will switch off, thus preventing a catastrophic accident. If the helmsman falls overboard without being attached, the engine will continue to run without steerage. In many cases due to the handing of the prop the outboard will swing to one side taking the boat on a circular route back to the vicinity where the helmsman has fallen into the water. A spare kill cord is an essential spare part to be kept aboard.

Outboard Maintenance Programme - All the above systems and many more relevant to the outboard motor form part of our comprehensive maintenance database, access to this database is available on a monthly subscription.

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