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.
How do I test my boat thermostat?
There is a simple test to determine if a thermostat is opening and closing properly. Place it into boiling water. It should open in the water and close when removed. If it fails, replace it and the gasket with new ones.
How do I know if my outboard thermostat is bad?
Symptoms of a Bad ThermostatEngine overheating, particularly at idle and low running speed.Engine going into limited power or slow mode to mitigate against overheating.Increased fuel consumption.
What temp does a boat thermostat open?
Two-Stroke Outboard Engines The thermostat opens at 118F – 160F (47C – 70C). The overheat warning activates at 160F (70C).
How often should a boat thermostat be replaced?
every two to three yearsTypically, water pumps and thermostats should be serviced every two to three years. This varies on where you do most of your boating.
Can I run my boat without a 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.
What are the signs of a bad thermostat?
Thermostat failure symptoms that you should knowHigh temperature readings. The main symptoms of a failing thermostat are related to engine overheating. ... Erratic changes in temperature. ... Leaking coolant. ... Increased fuel consumption. ... Unusual noises.
How hot is too hot for a boat engine?
The maximum cooling water temperature you should see on your instruments will generally be at or below 195 degree F. The cooling system in a marine diesel engine is fitted with a high water temperature alarm which will alert you if you exceed the safe operating temperature.
How does a thermostat work in a marine engine?
The thermostat is in a housing at the coolant outlet of the engine. As the coolant in the engine warms up past a preset temperature, the thermostat senses it and opens allowing coolant to circulate through the radiator to be cooled. Prior to opening the coolant just recirculates without passing through the radiator.
How do I know if my thermostat is opening?
Start your car's engine and allow it to idle. Look through the radiator filler neck to see if the coolant flows. At this time, it should not be flowing as your car has not reached the operating temperature to cause the thermostat to open. If you find the coolant is flowing, it means the thermostat valve is open.
How do you know if your outboard is overheating?
0:475:24Diagnosing an Outboard that Overheats - YouTubeYouTubeStart of suggested clipEnd of suggested clipEspecially if you don't have a temperature gauge or some type of indicator. Because if you see theMoreEspecially if you don't have a temperature gauge or some type of indicator. Because if you see the flow decreasing. It's a sure sign that something is going on down deeper in the motor.
Why is my boat overheating?
The number one cause for overheating boat engines is a problem with the flow of water to the engine. Most boats have a water strainer which catches harmful items before they can cause damage to your engine.
Why does a boat have a thermostat?
A thermostat regulates the temperature of the water for engine cooling and keeps pressure in the cooling system to facilitate heat transfer from the heads and the cylinder walls.
How do you know if your outboard is overheating?
0:475:24Diagnosing an Outboard that Overheats - YouTubeYouTubeStart of suggested clipEnd of suggested clipEspecially if you don't have a temperature gauge or some type of indicator. Because if you see theMoreEspecially if you don't have a temperature gauge or some type of indicator. Because if you see the flow decreasing. It's a sure sign that something is going on down deeper in the motor.
Is the water coming out my outboard supposed to be hot?
When you shut the engine off and water drains out of the water jacket through the tell-tale, stick your hand under it and it should be warm. Also, these outboards operate at much lower temps than a typical car engine. With a standard thermostat, they are running around 140 degrees F.
Should I change thermostat when changing water pump?
its a good idea to replace the thermostat whenever replacing a water pump. The thermostat may have suffered some damage during the overheating that occurred before the water pump failed.
Can a bad thermostat cause water in oil?
Finding water mixed in with your outboard engine's oil is a nightmare. Before you start tearing down the motor looking for cracks in the cylinder head or blown gaskets, you might want to check the thermostat. Believe it or not, a faulty thermostat can cause water buildup in an outboard's engine oil.
Why is the thermostat closed?
Thermostat Functions. Stays Closed - the thermostat should be closed when the engine is cold so that the block can reach its optimal operating temperature as quickly as possible. With the thermostat closed, coolant circulates inside the block but does not pass through the heat exchanger, where it would be cooled.
What happens if you remove the thermostat?
In some (mostly marinized "land" engines), the engine will likely run cool for much of the time which will promote carbon build-up, because the engine does not come up to temperature.
How does raw water work in an engine?
Raw water from the raw water pump bypasses the engine but still flows through the heat exchanger and exhaust elbow. In a direct cooled engine, the water by-passes the engine block but still flows to the mixing elbow in the exhaust elbow. What happens if the thermostat is removed depends on the design of the engine.
What happens if the thermostat does not open?
If the thermostat does not open, the engine will overheat, causing a temperature alarm to sound and risking engine seizure.
Can a thermostat leak if it is re-used?
If a torn gasket is re-used it will likely leak under pressure.
How does a thermostat work?
The strip works as a bridge in an electrical circuit connected to your heating system. Normally the "bridge is down", the strip carries electricity through the circuit, and the heating is on. When the strip gets hot, one of the metals expands more than the other so the whole strip bends very slightly. Eventually, it bends so much that it breaks open the circuit. The "bridge is up", the electricity instantly switches off, the heating cuts out, and the room starts to cool.
What is a thermostat called?
It's called a thermostat , a modern word based on two ancient Greek ones: thermo (meaning heat) and statos (which means standing and is related to words like stasis, status quo, and static—meaning to stay the same). We can tell just from its name that a thermostat is something that "keeps heat the same": when our home is too cold, the thermostat switches on the heating so things quickly warm up; once the temperature reaches the level we've set, the thermostat switches the heating off so we don't boil.
How do bimetallic strips work?
The trouble with bimetallic strips is that they take a long time to heat up or cool down, so they don't react quickly to temperature changes. An alternative design of thermostat senses temperature changes more quickly using a pair of metal discs with a gas-filled bellows in between. The discs have a large surface area so they react quickly to heat and they're corrugated (they have ridges in them) to make them springy and flexible. When the room warms up, the gas in the bellows expands and forces the discs apart. The inner disc pushes against a microswitch in the middle of the thermostat turning the electric circuit (and the heating) off. As the room cools, the gas in the bellows contracts and the metal discs are forced back together. The inner disc moves away from the microswitch, switching on the electric circuit and turning the heating on again. You can also find corrugated bellows thermostats in other applications (for example, older cars), and, instead of gas, they're sometimes filled with a volatile (low-boiling) liquid such as a diluted alcohol; the exact chemical inside depends on the range of temperatures over which they need to operate.
What is the difference between a thermometer and a thermostat?
Let's just be clear about the difference: a thermometer is something that measures the temperature; a thermostat is something that tries to maintain the temperature (keep it roughly the same). Photo: An electronic room thermostat showing a digital temperature reading (22.9°C).
What is a Honeywell thermostat?
Photo: A simple, mechanical Honeywell thermostat mounted on a wall. This one is marked in degrees Celsius. Once you've set the temperature, the thermostat is supposed to switch the heating on and off, as necessary, to keep the room more or less that warm.
How does turning the temperature dial work?
Turning the temperature dial moves the discs nearer to or further away from the microswitch in the center. That means the gas bellows has to expand more or less to turn the electricity on or off—effectively raising the temperature at which the switch triggers (and the room temperature).
What happens when a heat strip gets hot?
When the strip gets hot, one of the metals expands more than the other so the whole strip bends very slightly. Eventually, it bends so much that it breaks open the circuit. The "bridge is up", the electricity instantly switches off, the heating cuts out, and the room starts to cool.
What is the purpose of thermostats?
By constantly opening and closing, the thermostat keeps the motor at its ideal operating temperature. This prevents the engine from overheating, and ensures the fuel combustion is perfectly optimized to provide maximum power while minimizing fuel consumption.
What is a Thermostat?
A thermostat is a valve in the outboard’s cooling system that opens or closes depending on temperature. 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.
What happens if an outboard thermostat fails?
When an outboard has two or more thermostats and you have to replace one because it has failed, replace all the others at the same time. Outboard thermostats wear evenly, so if one fails, the others will soon follow.
How long does an outboard thermostat last?
When to Replace an Outboard’s Thermostat. Thermostats are fairly robust, and can last for several years depending upon how many hours you put on your outboard, and what types of conditions you run it in. For example, the thermostat of an outboard that runs in salt water will experience far more corrosion than thermostats in outboards primarily used ...
Why does my outboard thermostat keep shutting off?
Usually a thermostat remains closed when it fails, cutting off the supply of coolant to the outboard. However, a thermostat will occasionally fail in the open position or get jammed by corrosion or debris, thus allowing coolant to constantly flow though the motor regardless of whether the outboard needs it or not.
How to tell if thermostat is bad?
Symptoms of a Bad Thermostat 1 Engine overheating, particularly at idle and low running speed 2 Engine going into limited power or slow mode to mitigate against overheating 3 Increased fuel consumption
Can you replace an outboard thermostat?
Outboard thermostats can’t be serviced or repaired, so when the time comes to change them out, discard the used thermostat after installing a new one. The good news is that thermostats are inexpensive, and considering how important they are to the health and performance of the motor, buying a new thermostat once every couple of years is not something you want to cheap out on.
How does a bad thermostat affect water?
How a Bad Thermostat Causes Water Buildup. 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. In other words, if a thermostat fails in ...
Why does my engine have condensation?
When this happens, condensation forms within the engine due to hot engine oil coming into contact with cold engine surfaces. The condensation forms water, which mixes with the oil and eventually forms a milky residue.
Do Yamaha outboards have thermostats?
NOTE: Some outboards such as Yamaha V MAX models have two thermostats, in which case you would remove them both.
Can a faulty thermostat cause water buildup?
Before you start tearing down the motor looking for cracks in the cylinder head or blown gaskets, you might want to check the thermostat. Believe it or not, a faulty thermostat can cause water buildup in an outboard’s engine oil. If you find water mixed in with the oil, test the thermostat first before you panic.
