Thermstat opening temperature

Thermstat opening temperature

Author
Discussion

WhiteVanMan123

Original Poster:

1 posts

27 months

Sunday 25th October
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I'm just replacing the thermostat on a car and thought I'd test it before fitting it (I've had my fair share of DOA therms!) Most of the time I just chuck them in a pan of boiling water and see if they open.

This time the therm I'm fitting says it operates at 105c. I've chucked it in a pan of boiling water and it hasn't opened or even started to open. Is that 105c the temperature at which it starts to open or the temperature at which it should be fully open? If it's the former, how does one test it considering I can't get water hotter than 100c?

E-bmw

5,785 posts

111 months

Sunday 25th October
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Use the oven.

GreenV8S

28,497 posts

243 months

Sunday 25th October
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The nominal temperature is usually the point where the stat starts to open. Typically it will be fully open 8-10c above that.

Chris32345

1,107 posts

21 months

Monday 26th October
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What's it for as 105c sounds very high for the thermostat to open at?
Most engines usually operate around 90c and over 100c isnt good

phumy

4,966 posts

196 months

Monday 26th October
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Chris32345 said:
What's it for as 105c sounds very high for the thermostat to open at?
Most engines usually operate around 90c and over 100c isnt good
Why is it not good, the system is under pressure so its not going to boil, his engine might be designed to run at that temerature?

Chris32345

1,107 posts

21 months

Monday 26th October
quotequote all
phumy said:
Why is it not good, the system is under pressure so its not going to boil, his engine might be designed to run at that temerature?
Read it again most engines some may run at these Temps but a lot 110c or so will start bringing on warning lights or at least move the dial into the red section

Hence why I asked what engine



Edited by Chris32345 on Monday 26th October 11:23

phumy

4,966 posts

196 months

Monday 26th October
quotequote all
phumy said:
Chris32345 said:
What's it for as 105c sounds very high for the thermostat to open at?
Most engines usually operate around 90c and over 100c isnt good
Why is it not good, the system is under pressure so its not going to boil, his engine might be designed to run at that temerature?
I did read it again and you said this in bold above and i asked why isnt it good, if its been designed for it, it will be fine.

GreenV8S

28,497 posts

243 months

Monday 26th October
quotequote all
phumy said:
Why is it not good, the system is under pressure so its not going to boil, his engine might be designed to run at that temerature?
Glycol based antifreeze would be at the point of boiling by the time the stat is fully open. For the engine to operate at those temperatures it would need a more exotic coolant - and the engine itself would need to be designed for it too.

VanDiesel99

98 posts

27 months

Wednesday 28th October
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I'm not particularly familiar with modern stuff, but I have been in a BMW with a calibrated temp gauge and its 'normal' appeared to be 105c

Me, I'd be having kittens if my 1990's Pug got to 105c, it runs at a rather more sensible (IMHO) 82c, but things have changed

rigga

6,742 posts

160 months

Wednesday 28th October
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Modern minis run at 105 to 108 degrees before the fan cuts in although they have electronically controlled thermostats in the cooling system, no exotic coolant required.