[Corazon20]

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.

[antimatter15]

How do you know if your outboard is overheating?

[bootfast]

Secondly, what happens when you run a boat without a thermostat? more

[Kir]

Went thru the same search last year. Thought merc had really hidden it well then the experts here set me straight. The motor really runs cool (cold ?) without a t-stat. Temp gauge never exceeds 110F. Checked the sender accuracy with boiling water and the gauge was right on. Guess these motors just run on the cool side.

[rickyfoley32]

thanks, no wonder i couldnt find it.<br />thes less parts the better.

[Renton777]

Re: Do 1994 40 HP 4 cyl. Mercs have thermostats ?

[galeru]

Re: Do 1994 40 HP 4 cyl. Mercs have thermostats ?

[bitcoinboy]

Also, what is the purpose of a thermostat? Any liquid-cooled car engine has a small device called the thermostat that sits between the engine and the radiator. Its job is to block the flow of coolant to the radiator until the engine has warmed up. When the engine is cold, no coolant flows through the engine.

[mimarob]

As long as the system is operating the thermostat continues to control the flow of liquid through the radiator in accordance with engine cooling requirements. The purpose of the jiggle valve (a small pin-style valve) is to facilitate refilling of the system by acting as a self-clearing vent hole. more

[jorgeclam]

Similarly, how do you know a thermostat is bad? here

[JohnVChampion]

How does an auto thermostat work? more

[Huffmankatie]

I am an I/O guy. looks like a thermostat bypass of some sort to me.

[kmac]

I think it is basically a relase valve for bypassing the thermostat (that has closed off the heads from water coolant,) when the water pressure reaches a certain amount. Or if the thermostat is open to allow more coolant flow. more

[konaya]

the poppet valves are spring operated k , as the motor starts the impeller sucks water pushing it into the motor , that water has to go some where , next to the poppet valves is the therm-st k, when the motor is cold & the water has not reached temp & the therm-st is still closed , the pressure builds up pushes the poppet valves up, the spring compresses the valve opens up & the water goes out , also when the motor has reached temp the stat opens but does not handle the amount of volume that the impeller pumps when the rpm increases , that extra volume of water then goes out through the poppet valves & then out the exhaust . the whole idea to put the poppet valves there is to keep the water in the motor until it warms up , so if you start your motor & SUDDENLY take off the rpm picks up , more volume of water , its got to go some where , cause the pressure builds up, now remember you did not give the motor time to warm up for the thermostat to open up k if you gonna do that , poppet valves open water out & bobs your uncle , cheers m8t
what you can do is fit a **** hole in the thermostat cover , then when you see the water coming out , then you know your motor has warmed up , cause the thermostat has opened , then you ready to go.& at the same time it tells you the thermostat is working , cause you cannot see it opening .the water coming out , den you know for sure its working here