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Outboard engine maintenance

2014 April 1


ompared to the outboard motors of years ago, today's outboards are very reliable; however they still require some maintenance to keep them running at their best. A few simple procedures using a handful of tools will keep that motor humming, whether it is on your dinghy or your sailboat's transom.

Outboard motors have gone through a quiet revolution over the last decade. The smoky, poor running two-strokes of the past have been replaced by smooth running, quiet four-strokes. These motors are more expensive and heavier, but it's worth it because they run so nicely.

A great place to start your maintenance program is by reading the manual from the manufacturer. All motors are a little different, but the general themes are the same, and the maintenance manual will point out details specific to each engine.

Engine inspection is an ongoing task. Familiarize yourself with your engine. Does it sound right? Is it pumping cooling water? Does the prop have any chips or dings?

One of the biggest differences between four-stroke and two-stroke motors is the lubrication system. Two-strokes require oil to be mixed in the fuel, while four-strokes have pressurized filtered crankcase oil systems just like car engines. That oily gas mix can be a hassle; a little too much oil makes for smoky running and fouled spark plugs, and not enough oil is hard on the engine. Regardless of the type of outboard you have, it is important to change the oil and filter once a year. Fall is the best time because you don't want to let the dirty oil sit in the engine over the layup period.

Be sure to review the oil change procedures; in most engines you can drain the waste oil through a drain port instead of pumping it out with an oil change pump via the dipstick port. You should also periodically check the oil level. Most engines have a dipstick just like your car but be sure that the engine is level when checking the oil level.

Lubrication maintenance extends to the lower unit-the transmission and gearing of the engine-this should be done once a year as well. If you don't use the engine much, you can extend this maintenance to every other, but no longer. There are typically two plugs on a lower unit, one on the bottom to drain the oil and another on the top to act as a vent and level indicator. The procedure here is pretty easy, mount the engine somewhere that you can get a pan or bucket under the engine and remove both plugs from the lower unit. Once the oil is drained, you refill the lower unit from the bottom, you pump in gear oil until it comes out the upper hole. You put the upper plug in before you remove the pump, closing off the top plug will hold the oil in the lower unit until you replace the lower plug.

There are a few manual lubrication points in outboards too, usually in the control linkage. Check your user manual for details and use the recommended lubricant.

Spark plugs should be changed once a year, and it's a good idea to keep a spare on hand. Use a high-quality, name brand plug, but it doesn't necessarily need to be from the engine manufacturer.

Four-stroke outboards have evolved fuel systems, so they will have some form of filter and the fuel tanks will often have little sumps. Change or clean that filter once a year and assess the condition of the fuel lines at the same time, looking for brittleness and cracking. Clean out the fuel tank from time to time, by rinsing it with clean fuel.

It is equally important to pay attention to your fuel. I would not recommend storing fuel over the layup, even with stabilizers added, because modern fuels just don't store well. Burn the fuel in your car and get fresh fuel in spring.

There is a lot of discussion about the use of ethanol fuels in outboards. Although it is best to use non-ethanol fuel if possible, most outboards from the last 30 years will work fine with fuel containing up to 10% ethanol (also known as E10), but some manufacturers recommend additives that can help prevent oxidation that can gum up an engine. Fuels with more than 10% ethanol should not be used at all and could cause major damage to an engine.

Running an engine in salt water is hard on the engine, and even though they are designed to operate and survive this environment, a little maintenance can help. Hose down the engine externally to rinse off the salt water. A little wash and wax attention can help keep the engine looking good. Flush the cooling system as often as you can, this typically isn't practical every day but try to pay attention. Over time salt will build up in the cooling jacket and eventually will impact the cooling of the engine, but it is easily removed.

I find the easiest way to do this is with a product called Salt-Away (www.saltawayproducts.com), an acidic solution that comes with a small injector system. You just hook up the injector to a garden hose connected to a set of engine cooling muffs. The system will run a mildly acidic water solution through the engine, removing salt and mineral deposits to allow the engine to cool correctly.

When running in salt water it is important to pay attention to the corrosion control anodes on the engine. These anodes are designed to combat galvanic corrosion by dissolving before critical engine components do. These will typically be located on the lower unit, either a little puck sometimes a little fin. Check your manual for details on replacement. Plan to replace them when you see a little wear, because replacing these is much less expensive than something else corroding on the engine.

There are also a few long-term maintenance items. There is a little cooling water impeller that should be changed every three years or so. If you experience overheating or reduced water flow, check the impeller. The timing belt is important too, and it should be inspected every few months. If it looks cracked or brittle, replace it. Refer to a dealer or a detailed service manual if you need to do this, it is import to preserve the timing relationship between the crankshaft and the camshaft.

Running this list now will allow you to not worry about your motor out there on the water. Proper maintenance will allow your outboard to be just as reliable as the engine in your car.

What to do when your outboard acts up on a charter

Outboards on charter boat dinghies can be temperamental because these motors see a lot of use, but their performance is critical to the happiness of your vacation. Charter boats typically have limited tools, but there are a few tips that can make the experience better.

Dirty or fouled spark plugs can be a problem. You typically won't have a spare, but you may be able to clean up the one you have. You'll need a plug wrench to remove the plug and something to clean them with. You can clean them with WD40 but if you have nothing else Vodka is an option. Straight vodka is fairly pure alcohol and this will clean up a plug pretty well.

Do your best to keep the fuel tank clean and dry-water or dirt are big enemies. Close the vent when you are not using the engine.

Be prepared to jury rig the emergency stop lanyard, they do get lost. A bit of wire or a wire zip tie can be handy.

Study the engine in the light and memorize where the controls are, I guarantee you will find yourself on a dark dinghy dock, maybe in the rain, and you'll need to start the engine.