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  1. #1

    Thermostat , 158 or remove it ?

    What are the negatives to removing the thermostat ?


  2. #2
    HOSS's Avatar
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    None! Unless you ride in really cold water which I don`t. You can read in every mag out there in relation to thermostats. There will always be the one editor that prints an article about engines actually running HOT without one due to not enough time or good "heat soak" or heat transfer to take place. I`ve never in my life seen a motor of any kind in any application run hotter.
    Now this brings us to internal combustion engineering and design. Yes a specific piston/block design is engineered for certain thermo properties. Running a motor too cold will in fact wear cylinder walls, skirts and rings. This is where your riding water temps come into play. The water down here never gets below 63! And I`m not doing much riding then either. Most of the time the water here is in the 80`s. So I`m fine. Your engine will take longer to get to operating temperature. In myy case maybe 30 secs more without the thermostat. But operating temp will be down. Still safe just lower. This will in fact enable my intercooler to work better and my hull temp to drop. When you leave the dock you motor is not at operating temp. When you first start it its not. Most engine wear is at initial startup due to lubrication. This is fact. Other wear is from operating wear amongst other things. So you see, it comes down to water temps where you ride.

  3. #3
    Moderator RX951's Avatar
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    * For practical 4 stroke applications dealing with air transfer (fan) for heat exchange in a closed loop cooling system, no thermostat can allow it to overheat at higher speeds if that speed is maintained.

    This is also often indicates diminished capacity of the cooling system.
    The dimished capacity is due to the increase in heat prodced from the combustion process.
    The Delta T thus increases and heat absoprtion diminishes.

    Basiacally; the faster an engine revs, the more cylinder firings in a certain amount of time which means there is more heat to dissipate; and the engine's cooling system has lessened in capacity (residence & area), it will be more difficult to handle the extra heat.

    Once the engine is lowered in speed/rpm, the heat produced will decrease and the Delta T will narrow and heat absorption will transfer more readily.
    In an automobile application with no thermostat where ambient air is involved with a radiator as part of the heat-exchange process, it is very likely that a motor can overheat as the coolant will eventually reach the temperature of the motor as there is not enough residence time to allow heat absorption to take place.

    This is also true if no air flow is present in a fan coolant operation.

    *
    But in the watercraft application, the heat exchange-process is always in the water.
    The water temp is always steady.
    The only variable that will change is flow of the coolant due to RPM changes.
    The flow will fluctuate more if none is present vs having the orifice of the thermostat.

    Thermostats are calibrated in flow and size for each application.
    Another thing to note too, thermostats "miantain" & "regulates" the temperature and flow.

    Maintaining an engines temperature is crucial to energy and power efficiency and holding it stable and constant.

    Thermal expansion is important. Too cold a motor and wear will increase from added friction. In cooler climates, a thermostat will help a motor reach its efficient operating temperature.

    In warmer climates, a thermostat will allow a motor to maintain its operating temperature.
    On you guys motor, down in the lower states where water temps stay temperate year round, no thermostat would not hurt it.

    But [prolonged periods] of high RPMS without letting off can increase the risk for overheating as the coolant will not allow to stay in the heat exchanger long enough to transfer heat.

    Not having a thermostat down here given the warmer temps in the south, no thermostat will not be that detrimental to the motor.

    The flow will increase,
    The residence time will decrease
    Operating temp will slightly decrease
    Heat transfer (Delta T) will also decrease.


    But also given the implicit facts of No Wake zones, Idling, and Cruising Speeds some of the time & Geographic Location it may not be that big of an issue considering the location and riding habits.

    Engine modifications also play a role in this question too especially if certain modifications produce more heat.

    Personally for me, I would be more apt to keep the lowest temp thermostat you can find in there. ....thats just me.....

  4. #4
    I'm in warm water 80+ usually 100% of the time. My only concern is I'll cruise at 70 for about 30-45 minutes. Sometimes the lake/river is pretty smooth. This is one of the reasons I'm looking for a 160 automotive thermostat.

    Thermostats are calibrated in flow and size for each application.
    RX951 what are your thoughts on using an automotive thermostat do you think the flow would be calibrated differently

  5. #5
    daverxp4's Avatar
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    even for canadian guys (joke) the thermostat will be beneficial i usually cruise at arount 50 mph and small elapses of 5 min WOT.

  6. #6
    Moderator RX951's Avatar
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    Quote:
    Thermostats are calibrated in flow and size for each application.

    RX951 what are your thoughts on using an automotive thermostat do you think the flow would be calibrated differently




    Important note guys:


    Just like your body needs to warm up when you begin to exercise, your engine needs to warm up when it starts its exercise. The thermostat provides temperature control for your engine's warm-up period.
    This little temperature-sensitive spring valve stays closed during engine warm-up. When the thermostat is closed, it prevents coolant from leaving the engine and circulating through the cooling system until the correct running temperature is reached.
    The correct running temperature for most engines can be anywhere from 160 degrees F and 210 degrees F. When the right temperature for that particular motor is reached, the spring valve opens, allowing coolant to circulate through the coolign system to be cooled-- almost like our bodies begin to perspire after we've warmed-up.

    The temperature at which the thermostat is designed to open is called its rating, and may be stamped on the body.

    Lets say a thermostat that has preset temperature of 158 degrees. This is what the temperature rating in Degrees F rating the thermostat begins to open at. 158 Degrees F, it will begin to open and should fully opened at 200 degrees F.
    The opening of the thermostat allows coolant to circulate through the engine and cooling system. As the temperature of the coolant begins to drop, the element cools off and contracts allowing the thermostat to partially or fully close.
    Thus, by cycling open and shut, a relatively constant operating temperature is maintained..
    I don't think that an automotive thermostat will matter as they all work in the same fashion. But, I would try to stay with one that is for a 4 cylinder motor vs an 8 cylinder as the coolant capacity is different. Coolant flow to a V8 vs a 4 cylinder is different as there are more cylinder to produce heat and the flow requirements are different.

    I would also use a fail-safe one too if you replace it with an automotive one.

    I would also look at the cost of one for the exact application OEM vs. an alternative replacement.

    Also, can the temp rating you are looking for be found for your exact OEM application?

    If not, then the alternative would be a different application. i.e.) motorcyle, car, ect….
    And if you to, try to make sure it si the same size height ect....proper fit is a must.

    Here is a good link on basically the 3 styles of thermostats.
    I would also use a fail safe one too if you replace it with an automotive one.
    http://www.cooperstandard.com/us/en/...Thermostat.asp

  7. #7
    skipSC's Avatar
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    In outboards we would not remove them but gut them and leave the housing so the flow would be metered. If you just remove the thermostat, the coolant would not have as much a chance to absorb the heat generated by the engine. And the engine would take much longer to thermally equalize for proper engine performance. Just another opinion.

  8. #8
    HOSS's Avatar
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    Ah sorry ,,,big damn truck took out my line! All i can say as to what I read is,,,,,COUGH COUCH,,,,,BUlLLLSHIIIIT!

  9. #9
    Moderator RX951's Avatar
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    COUGH COUCH,,,,,BUlLLLSHIIIIT!

    you can go ahead and re-eat what you coughed up :P

  10. #10
    HOSS's Avatar
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    Doubt that,,,very seriously.

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