Thermostats - whats the deal??

Jongould · Jul 31, 2012

My 200 is currently not running a stat, I got it like this and I believe it was taken out as the gauge rear hot (disco sender fault) all the time. The engine is fine so nowt to worry about there. Basically I have fitted 2 stats now and neither of them show any signs of opening even when my gauge (have fitted a durites marine gauge now) shows it just under 100 degrees, definitley over 90 degrees...

What temp are they meant to operate? My understanding is open 88, close 82, I got this from the web so may not be correct. Can I get a lower opening temp one? Like a towing/hard duty one?

Dave90 · Aug 3, 2012

I'm sure you can get different temp one's, mine is rated at 88 degrees

natas · Aug 3, 2012

Hmm, so mine must always be open?
Even parked in the garage. Today its in the high 90's and very humid!

tottot · Aug 3, 2012

If you are running that hot with out a stat then the rad cant be to good. the stat does not control the engine temp it only helps the engine to warm up faster,unless it jams shut and causes overheating.

Dave90 · Aug 3, 2012

tottot said:
If you are running that hot with out a stat then the rad cant be to good. the stat does not control the engine temp it only helps the engine to warm up faster,unless it jams shut and causes overheating.

It does control the engine temp really, when the engine get's to a set temperature, the wax in the thermostat melts and opens to allow coolant water to flow through the radiator, if the engine cools to a set temp and the wax solidifies, the thermostat closes until the engine warms up again, but usually the temp will stay consistent unless the weather very cold or very warm

tottot · Aug 3, 2012

Dave90 said:
It does control the engine temp really, when the engine get's to a set temperature, the wax in the thermostat melts and opens to allow coolant water to flow through the radiator, if the engine cools to a set temp and the wax solidifies, the thermostat closes until the engine warms up again, but usually the temp will stay consistent unless the weather very cold or very warm

Most engines run normal at a temp higher than the switching point of the stat so it just remains open and the upper limit is controlled by the fan,but as you say the air temp on the day affects what happens.I think that jongould has most likely a blocked rad his stat should most certanly be open at 90 degrees plus.

tacr2man · Aug 4, 2012

The engine temp is not controlled by the fan , otherwise if you were going at higher speeds the engine would run cooler , as the rad cooling capacity always has to be well in excess of the engines ability to produce heat . If it is not then the vehicle will overheat when worked hard . The thermostat is what roughly controls the eng temp , subject to the previous rad cooling cap proviso . The fan is there to boost airflow to increase the rate of heat exchange in the rad, usually at lower airspeeds. HTSH

tottot · Aug 4, 2012

Engines and rads are matched so for most normal running neither stat or fan are doing anything, they limit upper and lower temp a motor is allowed to run at.An engine with out a stat or fan will run at normal temp if its not worked to hard or to little or is in too hot or cold conditions.Had a look at jongoulds marine gauge and it looks like a water level unit? If your engine is running at 100 degrees thats HOT either rad is not cooling enough or fan is not working.If it works ok with out stat then stat was stuck shut.

Thermostats - whats the deal??

Jongould

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Dave90

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natas

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tottot

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Dave90

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tottot

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tacr2man

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tottot

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