How does a Mercury outboard thermostat work?

What is a Thermostat? When the thermostat is closed, it prevents the flow of cooling water passing through the outboard, thus increasing the motor’s operating temperature. As the temperature rises, the thermostat opens and allows coolant to flow through the outboard, thus decreasing its operating temperature.

How do you test a Mercury outboard thermostat?

Step 2: Put the thermostat in a bowl and immerse it in boiling water. As the thermostat heats up, it should open. When you remove it from the boiling water, allow it to cool and it should close again. If the thermostat remains open or closed, it has failed and must be replaced.

What temp should outboard thermostat open?

between 50 and 60 degrees Celsius
A thermostat is designed to hold the cooling water in the block until it reaches the temperature set by the engine manufacturer. Generally, this is between 50 and 60 degrees Celsius. It then opens to release the water before it gets too hot and overheats the outboard.

What does the thermostat do in an outboard motor?

The thermostat prevents the cooling water from getting to the cylinder walls until there is enough heat for efficient combustion. Once the cylinder temperature is up, the thermostat allows the cooling water to flow from the water pump through the water jacket and out the exhaust.

Does my outboard need a thermostat?

If the engine overheats at idle, but runs great at mid-range or at wide open, then most likely, the thermostat needs replaced. If the engine is overheating no matter what speed, then the impeller is most likely the culprit.

Can outboard run without thermostat?

Can I Run My Outboard Without The Thermostat? Yes, you can temporarily run your outboard without the thermostat and not harm the engine. No, you can not remove the thermostat and continue running the engine for long periods of time without causing harm to the engine.

How do you tell if an outboard motor is overheating?

One of the best ways to tell if your outboard motor is overheating is by checking the dash gauge. You just have to look at the dash gauge for the temperature. If it is green, then you don’t have to worry about anything but if it goes from green to red, then it is an indication that your boat is overheating.

What happens when you run an engine without a thermostat?

A car without a thermostat would never even warm to operating temperature, much less overheat. The lack of a thermostat would create a constant flow of coolant through the engine, thus a constant cooling effect on the engine.

What does the thermostat do on an outboard engine?

The thermostat is a valve that regulates the operating temperature of the outboard by opening to let cool water flow through the engine, and closing to prevent the flow of water from inhibiting the engine’s ability to reach its ideal operating temperature.

Where can I find a Mercury Mariner thermostat kit?

Find thermostat kits for your Mercury Mariner outboard using the application chart from the Mercury Quicksilver catalog. Need other parts? If you need parts not listed in the application guide, please see:

What happens when the thermostat on a boat fails?

In other words, if a thermostat fails in the open position, water will continuously flow through the engine, and the motor will run too cold. When this happens, condensation forms within the engine due to hot engine oil coming into contact with cold engine surfaces.

How to diagnose a bad outboard thermostat?

1 Step 1: Remove the thermostat from the motor. NOTE: Some outboards such as Yamaha V MAX models have two thermostats, in… 2 Step 2: Put the thermostat in a bowl and immerse it in boiling water. As the thermostat heats up, it should open. When… More