Thermostat Inquiry.-

Sea Rider

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Sep 20, 2008
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Was wondering if it would be possible for a pristine in good working order thermostat to open al less temp than factory stated say less than 60C? when should open at +60 C?, any ideas.

Happy Boating
 

roscoe

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Oct 30, 2002
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21,657
Yes, but then it wouldn't be in good working order.

In my experience, outboard thermostats are not very precise, but I have only tested a few.
 

Sea Rider

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Sep 20, 2008
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I'm asking as there's the posibility for a thermo doing such, opens prematurely and cylinder head doesn't sufficiently warms up, OB misses slightly when openning throttle past idle after its 3-4 factory stated min warm up time. Does so only on cold next day starts or re starts when cold on same day, seems a thermo temp related issue. Will install a new one and see what happens..

Happy Boating
 

GA_Boater

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If the spring happens to weaken due to age or some other reason, the thermostat can open before the target temp. You can put both the new and old in a pot of heating water to see if they open at different times. Then you should know if the old one is in or out of spec.
 

Sea Rider

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Thanks,

To check need to suspend thermo right in middle of a pryrex cooking pot filled with water, thermo must not touch lower pot, say middle heigtht. While water heats slowly, suspend a thermometer next to thermo, if opens at 60C? it's good. If at less than 60C? still good, OB will take bit more time to fully warm up. If more than 60C? Kaput...don't use it or risk having a powerhead overheat..

My thermo is in immaculate clean cond, don't know if with time, use and abuse goes bad, opens prematurely ?

Happy Boating
 

phillnjack2

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Apr 30, 2011
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you can get different spec thermostats for different regions, this is not just an outboard thing its used like that in cars as well.
if you were to be using an outboard up near the artic the water would be terribly cold and you might find a thermostat that opens a touch later is what the dealers there use.
go down to florida and they might use a thermostat that opens early due to much warmer water.

what make of engine is this, and have you checked that the makers did not do 2 or 3 different temp units for this motor ?
 

Sea Rider

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Sep 20, 2008
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Tohatsu only makes one specific thermo for each of its HP engines, assume all other brands does same.

If working at the poles, thermo will take longer to open, needs to wait till operating head temperature is reached before it opens up.

Happy Boating
 
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