The inner workings of an outboard motor are complex, but the cooling system is straightforward. Water is instrumental in maintaining a safe operating temperature to avoid the costly repair of an overheated engine. Unfortunately, a large percentage of boat owners are unware how the engine is cooled and where the water is expelled. Should water come out of exhaust on outboard?

Where Is The Exhaust On An Outboard Motor

The exhaust on an outboard Motor is located at the base of the propeller. The gasses produced by combustion are released. 

When the vessel is in operation, look behind the boat and locate the bubbles trailing behind the motor. The trailing bubble line is a result of raw cooling water and exhaust as the engine operates.

How Does An Outboard Motor Exhaust Work

Unlike a car engine which regulates its temperature by coolant, outboard motors utilize fresh or seawater in which it is operating.

Intakes mounted on the motor below the water’s surface pull raw water in and distribute it throughout complex tubing up the shaft and around the engine. In the process, the motor temperature is reduced, and the water is mixed with exhaust fumes and expelled. 

The temperature of the exiting the engine is at a higher temperature than the water pulling into the intake. The water acts as cooling by transferring the highs temperatures from the engine to the water and releasing it overboard. 

What Are The Signs Of A Malfunctioning Exhaust System

There are easily recognizable signs to determine if the engine is not cooling correctly. All boaters should be aware of the signs to prevent the engine from becoming overheated.

Outboard Motors are equipped with a cooling water release port above the waterline. The release port displays a consistent flow of water when the motor is cooling properly.

Locate the ejection point with the engine running and take note of the flow. Should the water stop squirting or the flow become week, immediately shut the engine down.

Lack of water flow can indicate a damaged impeller, blockage of the water intake, plug in the interior cooling lines, and lastly, the drain port can become instructed. Each has varying levels of severity and results in different levels of engine damage. 

The key is to shut the motor down and inspect. Look for clear signs of restricted flow due to obstruction. In the event the situation does become remedied, schedule a service appointment immediately.

What Are The Dangers Of No Water Flowing Out Of The Exhaust

There are varying levels of danger associated with little to no cooling water flow through the engine and out the exhaust.

A complete blockage of water flow causes engine lubrication to break down. When lubricant properties fail to perform their function, metal parts make contact. The contact causes friction which melts the metals in the powerhead causing engine seizure.

Obstructed water flow cause outboard motor damage. However, the damage is minimal due to water partially flowing as opposed to a blockage. Internal engine temperatures will rise but are unlikely to cause complete engine block failure. However, make sure to have the shop assess the motor of damage and replace the oil.

How to Avoid Blockages And Poor Flow Out Of The Engines Exhaust

There are two primary reasons for the lack of cooling water flow in outboard motors. The first is a damaged impeller. 

Outboard Motor engine impellers must be replaced during maintenance intervals to prevent unexpected failure. The frequency of use has no implication on the timing. Impeller failure can be disastrous, mainly when operating well offshore in a single-engine boat. 

A second common cause of inadequate cooling flow out of the exhaust is due to intake blockage. Weeds, plastic, and other debris have the capability of shutting off flow completely.

So Now Can Answer Should Water Come Out Of Exhaust On Outboard

The next time you’re out on your boat, look for the bubble trail and peeing outlet with strong flow. Marine engines are fitted with temperature sensors for safety purposes. The alarms notify the operator of high engine temperatures. Look for the key signs of cooling water in motion to keep the vessel out of the shop and on your favorite body of water.