Quote:
Originally Posted by Daox
You think this happens even with the water pump cycling the water in the block? I would think it would be enough flow to eliminate hot spots... thats its job after all. Perhaps at low rpms... I can't say for certainty.
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No, I don't mean that there are hot spots, I was just explaining the cooling cycle that happens in the engine.
The water pump is constantly moving coolant, even if the stat is closed, so there aren't hot spots in the engine block. When the stat opens, it creates a new circuit which was previously cooler than the coolant in the block, which is then re-heated by the waste heat of the engine block.
I over-simplified it because it's a fairly difficult concept to comprehend at times. There isn't two specific sets of coolant at all times, since the coolant is turbulent, it is constantly mixing. What happens, though, is that the coolant heats up because of the block heat, and that opens the stat, which allows the coolant into the radiator, where it cools. The previously cooled coolant enters the block, and when it touches the stat, the stat closes down to prevent the coolant from flowing into the radiator to be cooled again.
If you boil-test a stat, you'll see that at a specific temperature, it will *pop* open semi-violently. As you lower that temperature, it will slowly close back down. If you quickly douse it in colder water, it will snap shut with the same force.
The stat's job is to modulate flow at all times, so it doesn't just open and stay that way when the engine warms up.
Also, under dynamic operation, an engine will heat and cool consistent with load (lagged response, obviously), which means that the coolant will be more or less heated by the engine, accordingly. This means that the thermostat needs to be somewhat dynamic in it's ability to restrict coolant flow in order to keep the engine cooled (or heated) properly.
Hopefully, that made it more clear, instead of making it more obscure.
