What does a automotive thermostat do?

[4WDKC]

I say it is a device that determines if the coolant in the motor is routed through the radiator or not and will bring the coolant to operating temperature.

Once it does that, its job is done. Should the coolant temperature drop below the rating of the thermostat, it wakes up and by routing the coolant away from the radiator, the temperature of coolant will again rise to the rating of the thermostat, and again it will route the coolant through the radiator.

Now here is the kicker. It has absolutely no control over the temperature rising and sometimes rise to overheating.

Just like the thermostat in your house, if you set it on heat at 68F, the house temperature will not go below, 68F. It has no control in how hot your house can get.

If you set the AC to 68F, the house temperature will not get hotter than 68F, but the house temperature can drop below freezing.

It only works in one temperature direction.

What say ye?

It doesnt determine routes like it switches paths to the radiator or the engine it merely allows coolant to flow or not to flow.

I've found without one the water pump circulates the water too fast not allowing the coolant enough time in the radiator to cool it. Then eventually caused it to overheat. I'm not saying it happens to every car or truck but, I have seen happen to some of them. They're a cheap and easy part to change so I don't see a benefit in not having one. I think the difference between the temps on them is how much they open and control the rate of flow thru the radiator and motor.

IT doesnt hold coolant in the radiator to cool it holds it in the engine till it gets up to temp, it overheated because the coolant wast staying in the engine sufficient time to be absorb heat from the block. Racers dont use thermostats they use restrictors in place of t stats for this reason.

I'm no engineer, but if its flowing faster through the radiator and doesn't have enough time to sufficiently cool, wouldn't that also mean its spending less time in the block to heat up?

And as far as the flow capabilities of the water pump go, is a fully open thermostat really much of a restriction compared to not having one?

I've always thought that "no thermostat can cause overheating" was just a theory and it's never been proven. Or has it?

agree with first part, yes it is next time you have one out look at the size of the passage when open vs the overall diameter of it, a t stat that never opens can and will cause an engine to overheat by not allowing coolant to exit.

Vette has a 160*, truck had 180*, dd has stock.... these also depend on your intentions.

 

[Blue Ox]

Put an OE thermostat in, and the problem went away with no other changes made.

Flow rate issue , I assume .

I had a similar problem with my Suburban. At high RPM the engine would consistently overheat. It appeared the flow of coolant at high speed would push the aftermarket 'stat shut. Replaced with an AC Delco part and the problem went away. Interestingly the aftermarket 'stat was rated at 180° while the GM was 190°. I think the aftermarket co. knew they had this problem and tried to get ahead of it with a cooler 'stat.

 

[73c20jim]

I agree with all you are saying. I might have worded it poorly.

The most important thing I was trying to say is has no control over the coolant's high temperature once it had opened.

 

[bucket]

What does everyone like to run and why? I.e. 195, 185, 175 etc.

In trucks, I like to run a 180 stat. It gives a 10-15* head start for pulling a load up a long hill. It's also warm enough that fuel injection will function properly and heat in the winter is sufficient.

 

[73c20jim]

On the street I run the one that is OEM. The water and oil need to be heated to a certain temperature to function properly.

Remember the thermostat does NOT control the high temperature, only the low.

If a motor runs at 200F without a thermostat, it will run at 200F with a 160F 180F, 195F thermostat.

If you run a 210F thermostat, the car will run at 210F.

 

[73c20jim]

http://www.tuneruniversity.com/blog/2012/04/low-temp-thermostats-whats-the-advantage/

 

[Camar068]

[QUOTE="bucket, post: 509606, member: 82" It gives a 10-15*[/QUOTE]

10-15°.......hold ALT 0176 for degree symbol. One of those geeks things I couldn't forget if I tried lol.