When it comes to powering a boat through the water, it requires an engine that produces combustion. Combustion engines are complex and require precise timing and mixing to maximize horsepower output. The powerhead generates the engines thrust. Just what is a powerhead on a boat?

Where Is The Powerhead On An Outboard?

The power to propel a boat is generated under the cowling, which is the upper portion of an outboard motor. Beneath the cowling is where the powerhead sits

The engine block is the core to powering a boat. The engine block consists of valves, cylinders, and pistons. In unison, these components work together to propel the boat. 

What Does An Outboard Powerhead Consist Of?

An outboard engine is a marvelous piece of engineering. Understand that air, fuel, and a spark must be in perfect harmony to make an outboard boat motor run.

The portion of the motor that generates power, otherwise known as combustion, consists of three main components. 

Engine Block

The block houses all of the moving components of an engine that creates combustion. Inside of the block is the crankshaft, pistons, cylinders, and piston rods. 

All of these components are found in both two and four-stroke outboard engines. A two-stroke engine requires a gas and oil mixture to lubricate the internal parts. Four strokes are much like a car engine that requires periodic oil changes. 


The crankshaft is a complex series of moving parts. The pistons are central to the engine and attach to the crankshaft.

Power is created by the upward and downward motion of the pistons. As a result of the movement, it rotates around the pistons, thus generating power. As more force is applied to the throttle, the speed at which the crankshaft moves increases. 

Cylinder Heads

The more visible portion of an engine block is the cylinder heads. The cylinder heads are fundamental in the creation of power.

Cylinder heads contain spark plugs, valves, cams, and the camshaft. Each of these components is instrumental in delivering ignition and rotation, thus creating combustion. 

What Causes A Blown Powerhead?

There is a multitude of reasons that cause boat engines to fail. However, the majority of the causes are preventable. Powerhead replacement is expensive. Therefore, take measures to avoid costly repairs.


One of the primary causes of engine failure is due to overheating. Overheating an outboard motor is due to improper water from the intakes by mechanical failure or a blockage. 

An engine that becomes overheated will seize. Seized motors most often require complete powerhead replacement. 

Insufficient Oil

No matter if it is a two-stroke or four-stroke insufficient oil levels cause engine damage. The damage often results in the engine seizing because the mechanical parts are not lubricated.

Due to lack of oil, engine seizure will occur rapidly, especially at high operating speeds when the internal components are under extreme workloads.

Freezing Conditions

Temperatures in the southern states like Georgia, South Carolina, and North Carolina can dip below the freezing point.

Residual water in the cooling system will expand upon freezing. As a result, of the expansion,  pressure is applied to the powerhead, which causes cracking and failure. 

To avoid cracking in freezing temperatures, tilt the motor in the down position to allow all of the water to drain. 

How Much Does A New Powerhead Cost?

Remember, in many cases, powerhead failure is avoidable. Take all necessary measures to avoid damaging the engine block because repair costs are exponential.

Depending on the severity of the internal damage, the option may exist to rebuild the motor instead of replacing the engine’s core.

As far as cost is concerned, a rebuild will top $1,500 while a brand new powerhead can exceed $5,000 or about half the cost of the engine sticker price. 

Care For Your Boats Engine To Extend It’s Life Span And Save Money

The cost of a boat and motor is a significant expense. Protect your investment by taking good care of the engine’s powerhead because it is the heart of the motor. The goal is to keep you, your family, and friends on the water and out of the shop. As shop time increases, so do the out-of-pocket expenses.