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How to Troubleshoot Outboard Water in Cylinders

by Chris Stevenson

Outboard marine engines work much hard than automobile engines. They do not have a feature that allows them to coast after a surge of power and momentum, like cars or trucks. For this reason, outboard engines wear out faster, absorb more heat over a longer period and work under a constant load. Outboard engine cylinders also take a beating when it comes to ingesting water from their environment or cracking as a result of improper winterizing procedure. Some outboard cylinders simply crack from heat and stress.

Observe the starting sequence of your engine on your next outing. Upon starting the engine, note whether the engine lugs during starting, or seems to pound or hesitate before the engine starts. Stop the engine. Unclasp the top engine cowl case. Use a socket and wrench to remove the spark plug, or multiple spark plug wires from the tops of the spark plugs. Use a piece of coat hanger wire to ground the ends of the plug connectors to the engine block.

Turn the engine over several times without ignition. If the starter seems to spin fast for a second, then catches and spins fast again, it could be the signs of hydrostatic lock. Water that has entered the cylinders will not compress and stop the combustion cycle. If the engine does not start or turn over at all, it could be a complete hydrostatic lockup.

Look at the condition of the exhaust smoke while the engine runs. Bluish colored exhaust that disappears after 30 seconds of warm-up is normal. Some amount of oil burning during start-up will occur and leave a low-lying cloud of smoke over the water.

Look for white smoke that looks like steam and lasts a minute or more after start-up. Steam will not linger on the surface of the water, but rise up very quickly. Steam in the exhaust indicates that water has entered the combustion cylinders.

Use a socket to remove the single or multiple spark plugs on your engine. Look carefully at the electrodes on the plug tips. Heavy rust or a white-tan accumulation on the electrode indicates water in the cylinder, resulting from a cracked cylinder or blown head gasket. Any wetness on the electrode that does not smell of gas or oil indicates the presence of water.

Pull the oil dipstick out of the engine case and examine the condition of the oil on the tip of the blade. Any creamy, frothy white or tan substance that resembles the consistency of a milkshake indicates the presence of water in the oil. Use a wrench or socket, depending upon the fastener devise, to remove the flame arrestor on the engine. If water dribbles out of the flame arrestor exhaust port, you have water in the cylinders.

Warnings

  • You can run a compression test on a cylinder by inserting a gauge in the spark plug cylinder and turning the engine over several times. Look at the high psi reading on the gauge and let the gauge sit for 5 minutes. If the psi leaks down to zero, you have a blown head gasket, bad valve or cracked cylinder.
  • Cracked cylinders or cylinder sleeves can occur as a result of the cylinder wall cracking at the location of the wet manifold, which will allow water into the cylinders.

Items you will need

About the Author

Chris Stevenson has been writing since 1988. His automotive vocation has spanned more than 35 years and he authored the auto repair manual "Auto Repair Shams and Scams" in 1990. Stevenson holds a P.D.S Toyota certificate, ASE brake certification, Clean Air Act certification and a California smog license.

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