Found the link/site below as well.  Nice write-up.  I must admit that I had heard the "slows the fluid down to improve heat transfer" and though I questioned it, the source was highly respected.  I searched a few other sites for laminar versus turbulent flow - with higher flows and flow velocities, the fluid is more turbulent and you get better heat transfer.  Nice smooth flow "laminar) creates a boundary layer right at the surface between the coolant and the block or radiator which limits the "mixing" of fluid and limits heat transfer.  Turbulent flow makes the boundary layer thinner and takes hotter fluid into the flow and deposits some cooler fluid back close to the boundary to grab more heat.  Flow restriction is necessary in some areas, however.  Different sized passages are used in head gaskets to ensure that all portions of the head get the same amount of flow front to back and side to side.  Good thread and has dispelled some myths that I had accepted.  http://www.stewartcomponents.com/tech_tips/Tech_Tips_6.htm

I didn’t realize this was a debate, I thought I was contributing for the sake of a fellow members cooling issues.

For the record it was never my position that stopping the coolant flow was to allow for the coolant inside the radiator to get more dwell time for better cooling, what I said was-

Daze wrote:

This idea that water needs to sit in the radiator, uncirculated, for periods of time to adequately cool the engine is simply not true. A thermostat is there to maintain heat not aid in cooling.

Jon Richard wrote:

A thermostat is there to maintain a relatively steady engine temp, it’s not limited to maintaining heat. A properly designed cooling system will expect that the charge of coolant flowing from the radiator when the thermostat opens will be cooler than the charge from the engine to the radiator. In order to ensure this will happen under different demands, loads, and ambient temps, there must be airflow through the radiator independent of vehicle speeds. It’s not a matter of coolant sitting in the radiator un-circulated for adequate cooling, but rather a function of radiator temps being maintained independent of the engine temp to properly exchange heat as needed.

ultrastang wrote:

The temperature you see on the temp guage is not an accurate reflection of what the actual temperatures are, at various points inside the engine

This holds true for the external components of the cooling system as well, which is why I believe the temp switch would serve Daze’s Galaxie better if mounted further down stream in either the lower radiator tank or inline in the lower radiator hose. Wherever that switch is mounted, the fans will run till the temp in that particular area drops to where the switch is set, and the fans job is to regulate radiator temps, not engine temps. Regulating the engine temp is the thermostat’s job.

DAZE ""BUT I stand by the argument that I have been arguing from the beginning of this thread and that IMHO Ultrastang's post backs up.  The function of a thermostat has never been to hold the water in the radiator so that it has a chance to cool more.  The only function of the thermostat is to hold coolant in the engine so that the engine stays hot enough to run at the optimum running temperature.  It is there to maintain heat not aide in cooling.
 
Maintaining heat is aiding in cooling.    It like the saying 6 of 1 or half dozen of the other. 

MarkinSC wrote:

DAZE ""BUT I stand by the argument that I have been arguing from the beginning of this thread and that IMHO Ultrastang's post backs up.  The function of a thermostat has never been to hold the water in the radiator so that it has a chance to cool more.  The only function of the thermostat is to hold coolant in the engine so that the engine stays hot enough to run at the optimum running temperature.  It is there to maintain heat not aide in cooling.
 
Maintaining heat is aiding in cooling.    It like the saying 6 of 1 or half dozen of the other. 

 
That is correct. The thermostat is the 'brain' of the cooling system. Its purpose, from a cold start up, it to cause the engine to quickly get to operating temerature. From that point, it opens and then its function is to hold the engine at its optimum operating temperature.

Too hot a cooling system and oil breaks down which destroys moving parts and mechanical damage results. If the engine runs too cool (as when deleting a thermostat from the system) then the viscosity of the oil is too high (not thinned enough) to adequately flow between critical clearance components --like main & rod bearings to name a couple, also resulting in mechanical damage.

The cooling system should be relatively cool while the oil should be relatively hot. The engine temp should be hot enough to cause the moisture in the oil to flash off, be sucked up through the PCV valve and then be burned off with the combustion process. If the engine never gets to its optimum operating temperature to do this ...well, we all know moisture (water vapor) circulated through an engine won't make for an engine with a long, happy lifespan.

Daze wrote:

MarkinSC wrote:

 Maintaining heat is aiding in cooling.    It like the saying 6 of 1 or half dozen of the other. 

Wow there really must not be anything good on TV, now we are debating semantics  

What I am trying to say is that having a functioning thermostat installed in the engine correctly will not make the system cool any more effectively.  (think I covered all the words to eliminate loop holes )  and that removing the thermostat so that the water can flow freely in the same system that just had functioning thermostat installed in the engine correctly, will not cause the engine to eventually overheat.  It also won't allow it to reach optimum operating temperature but that's a different issue that I am not debating  This is the statement that I have been arguing fervently against all along.

Derek wrote:

Ahhhgg!...... I've had this argument with many ah redneck in Florida. Okay let me see if I can explain this correctly. ...The purpose of the thermostat in your engine, isn't to let (Hot water out). It's to (Keep hot water in the rad), long enough for it to cool down before being introduced back into the engine.

 

Daze, your body  has a thermostat, its called the thyroid gland. It maintains your bodys temperature at 98.6.  so maintaining heat is aiding in cooling.  when the thyroid can't maintain your bodys temperature, too hot or too cold, hypothyrodism and hyperthyrodism respectively, then pills are required to aid the thyroid to maintain temperature.  When the thryoid fails completely, drs will basically remove the bodys thermostat altogether, either thru surgery or radiation, and you must take pills the rest of your life to help your body maintain its temperature, its optimal running temperature.  My point?  you can't do away with a thermostat, it will cause problems.

As far as Dereks quote,  the thermostat does keep water in the engine till it gets to a certain HOT temperature,  not sure if it actually helps keep the hot water in the radiator until it cools though, yes we want that to happen, but i think thats the design of the overall cooling system,  radiator size, type, number of rows, material, etc. that does that part. 
 

MarkinSC wrote:

Daze, your body  has a thermostat, its called the thyroid gland....My point?  you can't do away with a thermostat, it will cause problems. 

Your analogy is beautiful.  I agree with you, in fact I put the thermostat back in yesterday

I like to break things down to their simplest parts when a question comes up.  I want your help to help me understand this correclty.  It seems that someone postd an argument that keeping water in the radiator longer does not help it cool any more.

To simplify this, lets assume we have a simple radiator ALONE.  No engine to complicate things.  If I pour the radiator 100% full of 200 degree water and push it through the air for 30 seconds, the water will be cooled down a certain amount.  Now, if I do the same experiment, but I push the radiator through the air for one minute, it would make sense to me the water would get colder than if it was only done for 30 seconds.  I cannot see why this would not be true.

That said, the longer the water stays in the radiator, the cooler it will be when it comes OUT of the radiator.

Now, the complicating factor to this seemingly simple experiment is that the water being held in the engine by the thermostat is getting hotter and hotter all the while.  Waiting on the water in the radiator to get as cool as possible is creating an adverse condition in the block.

So, there needs to be a balancing act involved.  The thermostat holds hot water back until it reaches a preset temperature, then releases a bit of water into the radiator, at the same time, some of that cool water is coming out of the radiator.  When the cool water reaches the thermostat, it closes down, maybe just a little, maybe alot, depending on how cool the water is.  Then the cycle repeats.

The science of all this is sizing the radiator correctly to match the thermostat and the engine's mass and coolant volume so it all actually works.  That is the class I slept through, I guess. 

So...somebody 'splain it to me how water held in a radiator longer does not get cooled more than water held for a shorter time...  I'm listening...

Let me get my .02 cents worth in here. 160 degrees is too cool for an engine. 185-195 is optimal. And yes, without the thermostat can cause overheat problem. In fact (and this dates me) the old flathead V8s used a large washer in the two upper hoses to restrict coolant flow to not overheat. However modern engines work best at 192 degrees. And the pressure cap is used to raise the boiling point of coolant, amoung other things
Howard
 

Last edited by hmartin025 (8/28/2013 8:00 AM)

MustangSteve wrote:

.  If I pour the radiator 100% full of 200 degree water and push it through the air for 30 seconds, the water will be cooled down a certain amount.  Now, if I do the same experiment, but I push the radiator through the air for one minute, it would make sense to me the water would get colder than if it was only done for 30 seconds.  I cannot see why this would not be true.

Ultrastang article explains better than I can but basically in your one minute analogy the first 30 seconds will be more efficient in cooling than the second 30 seconds because as the hot fluid temp gets closer to the ambient temp the system is less efficient.

So lets take your simple approach and add just a bit.  Lets say 200º coolant in a radiator for 30 seconds cools 20º  That same coolant sitting for 1 minute might only cool 30º total because the rate of cooling decreases as the temperatures get closer.   Now you have a radiator and a tank, (tank substituting the engine still leaving out heat being added to the system to try to keep it simple )  both hold the same liquid volume and are at the 200º.  If you let the coolant sit in the radiator for 1 minute it drops to 170º then you mix it with the tank of 200º coolant the temperature will balance out at 185º

Experiment two you put the coolant in the radiator for 30 seconds and the temp drops to 180º  then you remove that coolant and pore the tank of coolant into the radiator for 30 seconds. (still one minute total cooling time) It too cools to 180º  When you mix the two fluids together the net result is 180º coolant. 5º cooler than cooling half of it for twice as long and then mixing the two together.  

Ultimately I would look at Ultrastang repost in blue it explains it much better than I can.  simple or complicated when a thermostat is closed the heat of the engine increases and when it is open the heat decreases.  Restricting the flow will not improve cooling.

I sure am glad my little old thermostat is smart enough to know all this.

Don't confuse me with the truth, my minds made up!!!!

Howard

Jon Richard wrote:

Well I'm glad it's working better for you and it was a fun topic for me, but I think for turnin' our collective crank you at least owe us a pic of the Galaxie
 

I'm crossing my fingers hoping my new 427 doesn't overheat.  I guess if it does, I will have to add more electrical doodads to fix it...

Going with 180 degree thermostat and 74 Maverick original 17" flex fan and a Griffin 24" wide downflow aluminum radiator with two rows of 1-1/4" wide tubes (most use 2" wide tubes).  Wish me luck!  

I don't think I could stand it if someone suggests removing the thermostat!

Last edited by MustangSteve (8/28/2013 6:13 PM)