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whats the reasoning for drilling a hole in thermostat?


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i'm currently running a 180* thermostat with a 30/70 coolant mix with water wetter. my rad and fans are running correctly. i'm just looking at seeing about making the car run cooler, i may look into a 160* thermostat, but have read before about drilling a couple 1/4" holes in the thermostat. i'm just wondering what the reasoning(besides allowing more coolant to flow) for this is and if it would be a safe option?
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1/4 inch holes would be over kill and defeating the reason you run a thermostat,, a single 1/8th holes will alow air to move freely thru the stat and out of the system,, also alow a little coolant to slowly flow maintaining a slightly lower temp then 180 f ,, all your more expensive thermostats have an air bleed hole already
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1/4 inch holes would be over kill and defeating the reason you run a thermostat,, a single 1/8th holes will alow air to move freely thru the stat and out of the system,, also alow a little coolant to slowly flow maintaining a slightly lower temp then 180 f ,, all your more expensive thermostats have an air bleed hole already

 

thanks Shelby,

 

i couldn't remember what size hole it was. i have no overheating problems with my setup. my temp is at a steady 210* on a hot day in traffic with no fluctuations. so i was just looking to run a little cooler

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  • 2 weeks later...

I think that my Stant 180 DEG engine coolant thermostat is either slowly operating or stuck in one position. I suspect this cuz since the weather has turned cooler the engine temp at the Dash coolant Temp gauge is just about 1/8th inch above the line at the bottom end of the scale. And in the HOT weather here in Atlanta, back in August, I was running at the mid-mark, or just a tad below it - and it took a while to warm up.

 

The Stant only has the 1/8th inch hole in it.

 

Based upon the above, I went to my "friendly" MITSU dealer and bought a MITSU thermostat PN MD97 2903 WITH THE MARKING OF 88 DEG C. This thermostat has a 1/8 inch hole drilled in it BUT IT ALSO HAS A BRASS LIFT CHECK VALVE ( for lack of a better term) IN THE 1/8th inch HOLE.

 

Why is the MITSU thermostat different than the STANT one?

 

What does MITSU know that required this lift check valve in the 1/8th inch hole?

 

Is the "lift check valve there to help warm up's in the winter?

 

I'm starting to think that the MITSU thermostat should be used vice the Stant or any other after-market thermostat. Similar to using the MITSU PVC valve vice any aftermarket one.

 

For what it's worth

 

KEN

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if you are at the 210 mark, that means you are at the boiling point for the water in your system. Think back to Physics class, water will boil at 212*, and all the water will remain at this temp untill all the water is boiled off, then the steam can/will increase in temp.

 

If you are at 210 (actualy probalby 212) then your car is probalby hotter than you realize, just that the water won't get any hotter than this untill it's all been converted to steam. Once you pass 210, you are pushing steam, and that won't absorb anywhere near as much heat as the liquid water did. It is then very close to quickly overheating (often with little warning).

 

Your water temps should always be within 10 degrees of the stat rating, if not, you aren't cooling the system propperly and the stt isn't regulating the temps anymore. That means wither your radiator is clogged or full of rust (rust doen't transfer the heat very well thought to the fins), the stat isn't functioning propperly, or the pump isn't moveing the water efficently. It's usualy one of the first 2.

 

88 degree Celsius = 190.4 degree Fahrenheit

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if you are at the 210 mark, that means you are at the boiling point for the water in your system. Think back to Physics class, water will boil at 212*, and all the water will remain at this temp untill all the water is boiled off, then the steam can/will increase in temp.

 

This is absolutely true... when the water is exposed to atmospheric pressure. Because the coolant is under 13psi to 16 psi of pressure, the boiling point is raised considerably. The coolant also raises the boiling further.

 

At sea level and with a 13 psi cap, the boiling point of pure water is raised to 246 degrees Fahrenheit. Don't ask me to prove the math because I used online calculators. :lol:

 

Toss in a 70/30 mix of coolant and water and that temperature will become 269. In other words, hotter than you'd ever want your engine to reach! :shock:

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Hmm, I nee dto do some more research ...

 

...

 

 

I found this:

 

http://www.are.com.au/feat/techtalk/coolan...COL%20SOLUTIONS

 

My calculator got 257 *F (125*C) with a 33/67 mix. I'm sure there are some hot spots in these motors that reach that temp, they will still boil the water in that spot if the baseline temperature is elevated from a faulty stat. Even if the coolant is all liquid, you can still get severe hot spots.

 

Looks like having a good radiator spring (elevated cooling system pressure) makes more of a difference on retaining a cooling systems ability to stay a liquid than just the presence of glycol.

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