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No ones even mentioned the consensus the 4 rows over 3 is a diminishing return compared to 3 over 2.
But seriously, the smartest and hardest professions ask questions that strive for a single correct answer. If my questions are answered i can put them into an infallible and logical syllogism that might prove I am wrong in spite of my anecdotal evidence. i'm ok with that..
Regards the "what is happening to you" as being some theory that "hotter water in equals hotter water out" is, as I say, only part of the story. It's the inability of the cooling system to keep up with the heat source. So, either your cooling system has some defect where it isn't working as designed or the engine is generating heat in excess of it's design. These cars were engineered with a significant "safety margin" between how much heat the engine could generate and how much heat the cooling system could shed, even in instances where ambient heat and humidity were very high. It isn't the "hotter water in" that is the issue, it's the capacity of the cooling part of the system.

As far as "will the heat pulling capacity of the radiator decrease or increase in relation to volume" question.... if you mean "volume" as in flow rate the answer is neither. If you mean volume as in the amount of fluid capacity of the radiator itself, with all other factors being equal (surface area, fin count, etc.) then the answer is still "neither". If you mean volume as in radiator surface area then the answer is, obviously, cooling capacity is increased. We have to stop thinking of coolant as individual molecules moving through the system. A good parallel is a closed electrical circuit with voltage being equal to the pressure in the system (how hard the water pump is pushing the coolant through), amperage being the rate of flow through the system, and resistance being the coolant passages that need to be followed. You can't increase the flow (amperage) without affecting pressure (voltage) or resistance. Since resistance is more or less a constant (other than thermostat actuation) it's pressure that will be affected.
 

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I'm seeing a lot of forest in this thread and no trees. We're fixing a 1965 Mustang cooling system, not going to the moon.

Having one myself, I think the 4-row radiator is not ideal. I think the reduction in airflow through the core offsets the increased cooling capacity. Air takes the path of least resistance. Start reducing airflow through the core and it may find a new path. My experience is also that engines produce a lot of heat at low throttle cruise because this area of operation is often ignored when it comes to tuning.

How's your vacuum advance set up?
What carb do you have?
How new is your engine (fresh builds can sometimes run hotter)?
How's the carb tune in general? Any surging at low throttle or enrichment problems when giving it gas?
Sorry if this information was stated, it may have gotten lost within the thermodynamics lectures.
 

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Regards the "what is happening to you" as being some theory that "hotter water in equals hotter water out" is, as I say, only part of the story. Thats the only part that matters for this discussion, and yes this>>> It's the inability of the cooling system to keep up with the heat source. So, either your cooling system has some defect where it isn't working as designed or the engine is generating heat in excess of it's design. These cars were engineered with a significant "safety margin" Which size radiators were in those Fairlanes, Galaxies, Broncos and trucks? between how much heat the engine could generate and how much heat the cooling system could shed, even in instances where ambient heat and humidity were very high. It isn't the "hotter water in" that is the issue, it's the capacity of the cooling part of the system. It is both in relation is the argument and as I tried to ask. If there is a finite capacity of water to rad contact, would time in the rad (what I think is Loki's low volume) increase or decrease cooling of the water once leaving the rad?

As far as "will the heat pulling capacity of the radiator decrease or increase in relation to volume" question.... if you mean "volume" as in flow rate the answer is neither. If you mean volume as in the amount of fluid capacity of the radiator itself, with all other factors being equal (surface area, fin count, etc.) then the answer is still "neither". If you mean volume as in radiator surface area then the answer is, obviously, cooling capacity is increased. Thats not what I think @vegasloki is saying.We have to stop thinking of coolant as individual molecules moving through the system. A good parallel is a closed electrical circuit with voltage being equal to the pressure in the system (how hard the water pump is pushing the coolant through), amperage being the rate of flow through the system, and resistance being the coolant passages that need to be followed. You can't increase the flow (amperage) without affecting pressure (voltage) or resistance. Since resistance is more or less a constant (other than thermostat actuation) it's pressure that will be affected. You keep talking around the issue like its about to become political:) Funny to me since increasing the load in either increases heat.
 

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I'm seeing a lot of forest in this thread and no trees. We're fixing a 1965 Mustang cooling system, not going to the moon.
It’s the physics of how this works and the relative lack of understanding of how this translates to the application. Most of the anecdotal stories of what happened where and what they did show a lack of knowledge of the basic principles and based on hunches and myths handed down over the years. It’s not reasonable to expect everyone to know the nuts and bolts of the physics just as it’s not reasonable to discount them out of hand based on myths and misunderstandings.

Some of these misnomers include running a lower temp thermostat to prevent overheating and in general not being familiar with what the job of a thermostat is in the first place. One is 200* being too hot for these cars. Another is increasing the velocity of the stream making for better cooling. Yet another is dwell time within the cooling vessel. These are presented as fact when they flying the face of proven engineering practices and basic physics. If it’s fact it can be proven and replicated with data but in many if not most cases here it’s taken as gospel on little more than an observation. Like the profs used to tell us “prove it and show your math and citations”. What we see in many suggestions is a perception of cause and effect in a single system (eg. “I put this part on and it cured my issue) and not really what is happening that could have solved the issue or if it’s a Band-Aid that’s masking the real problem.

Like Bart and others are saying the reason these now old cars are having issues isn’t because of an inherent design flaw. The ran great when new and for a few decades after that. In the meantime things on and inside the engine have changed. Wear and tear, incorrect or poor quality parts or changes to the engine that exceed the design parameters. By using some of these simple methods such as cleaning the water jackets in the block, using the best parts you can get and replacing aging parts you can get your classic running properly again. When one plays parts darts without fully understanding what is happening in basic manner (not talking about deep physics here) it’s not addressing the core of the problem.
 

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Which issue am I talking around? The OP has a car that is supposedly overheating. The reason it is overheating is because the cooling system can not keep up with the heat load being placed on it by the excess heat generated by the engine.... for SOME reason which, to my knowledge, has NOT been determined. A number of potential causes have been mentioned and it will probably take the process of elimination to find out which is the cause(s). You have referenced some common myths about automobile cooling systems in general and Mustang's, specifically, that have been addressed, yet the answers given by multiple people do not seem to satisfy you.

In an attempt to, once and for all, address what seems to be the "sticking point" as I see it...

a. Slowing down the flow in the cooling system WILL, when the coolant in the engine becomes saturated (its temperature equals or exceeds the surface temperature of the metal that the coolant is trying to remove heat from) RAISE the engine temperature. THIS is exactly the function of the THERMOSTAT in the automotive cooling system. When the engine is cold, the block, etc., and coolant is at the ambient temperature. You start the engine and the thermostat is closed. The engine heats up and transfers the heat to the coolant. Some engines transfer heat faster than others. Diesel's are known for their very slow rate of warming up due to the mass of the engine assembly. Anyhow, as the engine keeps generating more and more heat, the coolant keeps getting hotter. At some point the coolant temperature is high enough to actuate the thermostat and it begins to open. Some water flows. If enough water flows and is cooled by the radiator and the cooler water re-enters the engine and balances the heat being generated the thermostat will stop opening and "modulate" to a point where it allows the proper amount of flow to maintain the minimum temperature. If the heat generated by the engine exceeds the ability of the cooling system, with the thermostat open wide, to offset the heat generated then the engine temperature will exceed the thermostat's minimum.... it may settle at some point a few degrees, fifteen degrees, thirty degrees.... whatever.... higher than the thermostat's rating when that point of equilibrium between heating and cooling is reached.

b. "Time in the radiator", when you are talking about a closed cooling system, isn't a factor. Ideally, unless you've botched up your flush and fill, there is little, if any, air in the system, which means that coolant is present throughout and in constant contact with the radiator and the engine assembly and all the hoses and parts in between. You slow down the flow in one part of the system you slow down the flow in the ENTIRE system. That would, in effect, be like CLOSING the thermostat as the engine gets hotter.

c. DYNAMICALLY, your "time in the radiator" argument doesn't hold water (like that pun?)... HOWEVER, if you DOUBLED the size of the radiator you would be increasing the surface area available for cooling and the total volume of the cooling system. All other things being equal... water pump, system restrictions, etc., if your water pump is moving "x" number of cubic feet of water per minute and you have increased the volume of the system than you have, effectively, slowed the flow rate of the coolant, but it isn't the decreased flow rate that is the factor but, rather, the additional surface area available for cooling. Also, your flow rate decreases exponentially due to surface tension between the coolant and surfaces and the friction between the water molecules so doubling the size of the radiator doesn't nearly approach doubling the cooling capacity of the system.

d. Yes, there are mathematical formulas that relate to the physical properties of ALL the system components... the chemical composition of the coolant, the flow rate, the surface area of the water jackets, the mass of the engine assembly, the characteristics of the radiator..... that's the information the engineers crunched with their slipsticks to come up with the appropriately-sized radiator.

PHEW!
 

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Slipsticks. Ha. How old AND geeky do you have to be to catch that?




Wait, holy crap, I'm old and geeky.
 

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Didn't even bother to read that last screed past the first bit. The OP merely mention it was running hotter on the highway, 200*, NOT OVERHEATING. I said why I thought it was "hotter" and you mostly agreed on the how and why but don't seem to accept that you agree with me.
 

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It’s the physics of how this works and the relative lack of understanding of how this translates to the application. Most of the anecdotal stories of what happened where and what they did show a lack of knowledge of the basic principles and based on hunches and myths handed down over the years. It’s not reasonable to expect everyone to know the nuts and bolts of the physics just as it’s not reasonable to discount them out of hand based on myths and misunderstandings.

Some of these misnomers include running a lower temp thermostat to prevent overheating and in general not being familiar with what the job of a thermostat is in the first place. One is 200* being too hot for these cars. Another is increasing the velocity of the stream making for better cooling. Yet another is dwell time within the cooling vessel. These are presented as fact when they flying the face of proven engineering practices and basic physics. If it’s fact it can be proven and replicated with data but in many if not most cases here it’s taken as gospel on little more than an observation. Like the profs used to tell us “prove it and show your math and citations”. What we see in many suggestions is a perception of cause and effect in a single system (eg. “I put this part on and it cured my issue) and not really what is happening that could have solved the issue or if it’s a Band-Aid that’s masking the real problem.

Like Bart and others are saying the reason these now old cars are having issues isn’t because of an inherent design flaw. The ran great when new and for a few decades after that. In the meantime things on and inside the engine have changed. Wear and tear, incorrect or poor quality parts or changes to the engine that exceed the design parameters. By using some of these simple methods such as cleaning the water jackets in the block, using the best parts you can get and replacing aging parts you can get your classic running properly again. When one plays parts darts without fully understanding what is happening in basic manner (not talking about deep physics here) it’s not addressing the core of the problem.
It looks more obvious I must not be speaking proper engrish sentax structures so I be kept this un shote
Does more time in the rad result in lower or higher temps out the bottom? Does this dwell time equate to more or less "volume," as you mentioned earlier, volume through the rad?
 

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Younger folks STILL won't know what that is. :D
 

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Lots of interesting theories.

Heres my take:

I use a laser temperature gun and measure the temp at the top of the radiator and at the bottom of the radiator. Coolant out and Coolant in.

What you want is the temperature at the top of the radiator to be nearly equal to your designed thermostat rating. If the temperature is much higher, then the engine is either producing more heat than the cooling system can discharge or the cooling system is under rated or not operating properly.

For this example lets say the top (core) temperature is 190° and the bottom temperature is 180°. A 10° difference.

Small vs large radiators: A large radiator with more cooling fins requires a lessor temperature difference between the core temperature and the ambient temperature to achieve the desired 10° temperature drop., While a smaller or less efficient radiator would require a greater temperature difference to achieve the desired 10° drop.

Removing the thermostat or installing a 165° unit does not help cooling. The engine is designed to run at x° and modifying the cooling system does not change that.

Flow rate is determined by the design of the system and engine rpm. The amount of coolant has no bearing on flow rate. The system flows x amount, be it a 2 gallon or 10 gallon capacity.

Altering the flow rate with a higher gpm WP or increasing the coolant capacity will change the amount of time that it takes each molecule of water to complete one "lap" through the system.

Ideally, the engine transfers heat to the coolant, the radiator then transfers that heat from the coolant to the atmosphere. In a properly operating system that 2-step process happens over and over.

There are many factors that can prevent that 2-step process from occurring. I think most of them have been covered.

My advice, use a laser heat gun and take some temps.
 

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Probably a dumb question but here it goes. Our radiators are designed to fill up to cover the fins. That leaves an air gap at the top. Is there any benefit of using a overflow tank with a radiator cap that allows fluid to be sucked back in when the car cools. That would allow complete filling of the radiator eliminating the air gap.

Allen
 

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Can i call it science and not anecdotes if I've predicted and replicated results? I've over filled so many things before....

I "think" the instruction to cover the fins is two fold. 1 it gives max fluid and a buffer for expansion, 2 once its over the fins a bit it should also be full in the upper hose indicating that the entire block is full. After a heat cycle of course.

I can't see a net positive to filling completely, that space that was for the hot water to expand and pressurize the air is now gone so with heat and pressure it by-passes the cap into the overflow. That overflow would have expanded to fill the empty space. I see no net positive to it, except....
My guess is that new-ish cars of the last 25 years or so use the expansion tank with two level markers to more easily verify the fluid level without taking off the cap.
 

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Probably a dumb question...
Not dumb at all. many people have found if you overfill an old Ford it will spit out some of the excess coolant. They "like" that air gap. What you are proposing would simply keep that coolant from being spat out. Not a bad idea, and exactly why some people add such tanks. Some race cars have a simple "catch can" meant to ensure not coolant gets on the race track surface. Also a good idea.
But if you want to fully fill the radiator, what you are really after is a "degas" setup. About everything new uses these. The idea is to have the system completely full of fluid with no air (gas) in it to cause problems with air pockets, aggravate cavitation issues, and boilover/steam pocket problems. New cars tend to run hotter than our old stuff. On purpose, for more power and fuel efficiency. But this puts them kind of on the edge of mechanical danger so they need more precise control of the engine cooling and a degas setup is part of that.
Kind of overkill for our old stuff but not a bad idea, I have seen evidence of cavitation damage on our old stuff. What I haven't seen (or just not noticed) is a degas setup for us. One main problem is the setups look a heckuva alot like traditional overflow reservoirs.
 
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