Overheating - Thermostat Testing

[MUD-PIGSIERRA]

Hey guys thought this might be a suited to a more general tech question than just the Zuk section. The thermostat in my Sierra says 82deg so I assume that's what temperature it would open letting cooland flow through the motor quicker...? So I want to test to see if it is opening around this temperature. Now my question is can I boil water in the kettle chuck the thermostat in a glass cup or what not and pour in the boiling water (assuming water boils at 100deg) and that once the boiling water hits the thermostat it will open straight away and if it doesn't its broken, or does the thermostat work around the slow heating of a engine and require slow heating as in to properly test if its working ill need to put it over the stove and bring the heat up slowly...?

Everything else in the Zook is all good new radiator coolant, oil etc etc. It never used to rise above 1/4 and would only require the thermo to come on after either heavy mud work or long periods of slow crawling and even then it would still sit just on half way on the gauge.

[croozaman]

prob best way is to heat it in a pot on the stove with a thermometer to tell what temp it opens and so you can see if it opens up properly

[MUD-PIGSIERRA]

Well decided i'd go test out both theories, putting the thermostats in a cup and pouring boiling water did not seem to open three different thermostats I had and I was finding it hard to believe that all three did not work. So I put them in a pot and put them in water just to the tip of the thermostat that way if they worked I would see them rise out of the water and well they would open up, one opened up earlier than the other two but the others both opened as well. I don't have a thermometer though but I was getting bubbles coming up from the bottom so it would have been pretty much close to boil.

[turkey]

X 2, thats the way I've always tested them in the pot on the stove...

[chimpboy]

Hey guys thought this might be a suited to a more general tech question than just the Zuk section. The thermostat in my Sierra says 82deg so I assume that's what temperature it would open letting cooland flow through the motor quicker...? So I want to test to see if it is opening around this temperature. Now my question is can I boil water in the kettle chuck the thermostat in a glass cup or what not and pour in the boiling water (assuming water boils at 100deg) and that once the boiling water hits the thermostat it will open straight away and if it doesn't its broken, or does the thermostat work around the slow heating of a engine and require slow heating as in to properly test if its working ill need to put it over the stove and bring the heat up slowly...?

Everything else in the Zook is all good new radiator coolant, oil etc etc. It never used to rise above 1/4 and would only require the thermo to come on after either heavy mud work or long periods of slow crawling and even then it would still sit just on half way on the gauge.

This is not quite right, the thermostat should start to open below the stated temp and be fully open a few degrees above it. The total operating range is usually about 8-10 degrees.

Anyway, I have tested plenty of thermostats the way you've described and they definitely should open before normal boiling temperature if they are working properly.

[MUD-PIGSIERRA]

Thanks for the input guys, I figure two are broken or just not working in their range any more....? I could be wrong but if the one that was in there was opening to late which would be why my temp was sitting up quite high then was being cooled it was probably closing to soon again which was not allowing the engine to get back down to lower temperatures...?

I took the Sierra for a drive down the road without any thermostat, had traffic lights stopped at servo left it running whilst I checked tire pressures, talked to a mechanic who wanted to know about the lift, then drove home temp gauge pretty much sat under half way on highway cruising, whilst at idle at the service station it dropped right down. I called up AutObarn to see if they had any new thermostats, they said they had a listing for two different temperature ranges one what might be for colder climate areas maybe with a higher opening temp, and one that comes on at a lower temperature so I'm grabbing the one that opens up at a lower temperature and I'll see how it goes.

[chimpboy]

I would get the hotter one as it improves fuel economy, as long as it is still a safe operating temperature for the engine.

[Bumpy45]

For a more accurate result keep the thermostat off the bottom of the pot and stir the water with a spoon keep the thermometer near the thermostat.