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In the interest of keeping things civil, and so I can learn, I have had a dump truck that collapsed a lower hose until I put a spring in it and I always thought running an engine without a thermostat was something one did temporarily when the thermostat wouldn't open or was clogged, and it actually would keep an engine from reaching its optimum operating temperature for much longer versus having one, i.e. cold starts and screwing with ported vacuum switches, chokes etc.
 

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I had a friend that was a cold storage refrigeration engineer. His theory was that removing the thermostat could not make it run hotter because if removing it caused it to circulate through the radiator too fast to dissipate the heat it would circulate too fast through the engine to absorb the heat. He was plant engineer for a two-million sf cold storage food facility. Heat transfer is what his specialty was.

Removing the thermostat causes the temperature to vary which cause parts to expand and contract which causes excessive wear. The tolerances are designed for a constant operating temperature so it is never a good idea to run an engine without a thermostat.

This debate about coolant flow and temperature goes on all the time on the flathead forums. The story that has always gone around is that a flathead V8, with its two water pumps, circulates the water too fast too cool it. What guys have been told for 70-80 years is to stick a washer with 5/8" size restrictor hole in each upper hose to slow the flow down. Other people cut off every other fin on the water pumps. Ford engineered weren't stupid, if it would have cooled better with those modification they would have done it.

One day I was reading an original 1940s Midget racing article and I ran a cross where those myths came from. There were no pressurized radiator caps back then. A track roadster of Midget could turn 5000 rpms on an 1/8 or 1/4 mile circle track. At high rpms the pumps would pump the coolant faster than it could go flow through the radiator. Without a pressurized cap the coolant went right out the overflow tube. They had to slow the coolant flow down for high rpm racing. It had nothing to do with making the engine run cooler. People still put those restrictor washers in because of those stories have been repeated for 70-80 years. No remembers that was a racing trick and not a daily driver trick Actual testing has proven that faster circulation improves the cooling on a flathead.

Here are some statements from some of the most visited internet sites.

This one makes absolutely no sense to me????

Typically removing the thermostat will cause the engine to overheat at normal operating RPM. ... When the restriction is removed by removing the thermostat, at idle too much coolant will flow typically causing the engine to fail to reach it's operating temperature.

This guy makes the most since to me. He said, "I think the concept arises from the fact that sometimes removing the thermostat worsens an over heating problem. Since with less flow restriction the coolant circulates faster, 'obviously' the overheating must be because it is moving 'too fast' through the radiator. The actuality is that the flow resistance provided by the thermostat (which of course is at the outlet of the system) greatly increases the pressure in the block and raises the boiling point so that local hot spots don't flash to steam and insulate the metal from the coolant. Such a process can snowball until a major meltdown occurs."

What he said above might come from the vehicles having thermostats but not having pressurized caps. So the thermostats restriction did create a little pressure inside the engine. For every one pound of pressure you raise the boiling point four degrees. So if the coolant system was just about at the boiling point and there was not a pressurized cap. removing the thermostat could cause the coolant to boil.


I have found argument after argument on this subject but nothing from a reliable source like a Thermostat manufacturer. I checked at Stant who makes more thermostats than probably all the other manufacturers combined. They only talk about it running too cool and not maintaining a consistent temperature which causes premature wear. I have seen many, many thermostats stick open and prevent the engine from warming up The first complaint is their heaters are not putting out hot air. I have never seen a stuck open thermostat cause one to get hot. A stuck open thermostat is not the same as removing one. removing one would increase the flow more than a stuck open one. Nobody has ever proven to me that removing one would case it to run hot.

Another guy suggested that faster circulation would mean the coolant made more trips through the radiator so it should cool better. That makes since too me also.

Good short thermostat YouTube video. Everything he says is correct.

 

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VFG -you are entirely correct. As a mechanical engineer with a master's degree and 15 years designing in the aerospace industry (including dealing with heat issues), I could write a book on how all these old wives' tales are simply wrong.
Simple answer: you need a thermostat (it determines the engine's cruising temperature), you need a radiator with a large enough fluid capacity to deal with the heat (bigger is better), and a high-volume water pump is rarely necessary and could cause cavitation (which worsens the problem).
 

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I had a similar problem with a dual fan on my mach. Basically came down to air flow, fan was restricting flow at speed. Removed electric fan and went back to mechanical fan no other changes problem solved.
 

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I think we're talking past each other. I'm not saying no stat will cause over heating(although it can in worst cases) but a rise in temps in most, yes! Take away the variable of air flow as mentioned above and lets agree the variable of adding heat from running harder rises.
Now please tell me how a radiator can remove more heat as the water temp rises. Tell me how hot water is not even hotter after passing through the engine.If the water is X and the rad can remove up to y heat before the engine adds z heat then x-y+z=X2-y+z=x3-y+z=X4-y+z=x5. (forgive the poor expression). BUT hotter water going in is going to equal hotter water coming out, every time. Hotter water going through the engine is going to come out even hotter, i dont know if its linear or exponential since i barely passed geometry. The only way i can see to cool the water more is to have it be in the radiator longer which a higher stat rating will do. Foregoing the anecdotes, without a stat, or with a low stat, in a marginal system the temp must rise. Right or wrong and why?
 

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If coolant is spending more time in the radiator to get cool, it will also be spending more time in the engine getting hot.

Coolant flow through the radiator = flow through the engine.

The best way to improve cooling ability is to increase the surface area of the heat exchanger.
i.e. get a bigger radiator
 

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I've seen it happen on some of my cars that were not Mustangs. One was a Toyota. It normally didn't seem to have a problem. But when driving it on long trips in the summer the temp gauge would slowly start to read higher than normal after driving 100 miles. Turned out there was a perfect circle of cottonwood fuzz between the condenser and radiator caused by the fan that was not visible until the radiator was pulled out. If the car was never driven over 100 miles it would not have mattered for several more years until the blockage because worse. In the coldest days of Minnesota winters, I use a piece of cardboard in front of the radiator with an 8-inch hole in front of the fan. If the outside temperature gets much over 20 degrees the gauge will start to climb after about 20 miles of freeway driving. When I got my Cougar it didn't have a fan shroud. It was fine until I moved to LA.
 

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Unless you guys found a way to break the second law of thermodynamics in a closed system :p some of what has been posted is not accurate and not supported by science.

Among them...

Starting with the basics. A thermostat in an automotive cooling system has one task. The task is to restrict the flow of coolant until the engine reaches the optimum temperature operating window. Once that window is reached the job of the thermostat is complete. The thermostat doesn’t prevent overheating. The thermostat only causes overheating when it fails closed or is not able to open as intended and blocks coolant flow to the radiator.

Velocity of the cooling stream having an impact on heat transfer is false. It‘s not the rate, it’s the volume. It’s the amount of coolant being able to be applied to the cooling vessel as well as the capability of the cooling vessel.

Same goes for time coolant spends dwelling in the radiator. Heat transfer is instantaneous at the molecular level. If the cooling vessel is of a suitable size and material there shouldn’t be an issue. One issue is when the heat generated overwhelms the design capability of the cooling system.

It’s not linear and is in part based on a delta between the hot and cold parts of the system. It’s a quadradic equation. That means it’s an unknown second power (a square of the number) that is solved as all the variables are calculated. That’s why we can’t say unequivocally that the temps will rise at a uniform level between diiferent systems of different designs or even systems of the same design.

So what does all this mean to us? In practice nothing. It’s in the weeds math. In terms of how the system works it’s the science on which an automotive cooling system is based. What we can do is make sure our parts are in good shape, working as intended. Ensure we’re using the right parts and that those parts are suitable for the degree of our build and tune. My plain Jane 289 driver isn’t going to need the same as a badass stroker or Coyote.

In many of these old cars and certainly with my driver years of use leads to a less effective system. I easily put 20 gallons of water after a liter of flush. It took that much to get the water mostly clear. The first few gallons it was coming out in reddish brown chunks.

Want more proof as to how this works? Cool. Many of us have a lot of time on our hands now...

This is what we used at Cal Poly Pomona some years decades back.
Thermodynamics, Kinetic Theory, and Statistical Thermodynamics (3rd Edition)
From a spot check on the Google it looks like many profs are using this one now.
An Introduction to Thermal Physics
 

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Yes, @MrFlash and @vegasloki, but which is greater, the rates of the rad to remove or the engine to add heat? Wouldn't the radiator have a finite ability and a degrading ability at that to some point, to lower temps? Meaning that it might take 185* to 150* but will it take 200* to 150* in the same amount of time?
I'll toss an anecdote of my ongoing "science." Car came with a punched out stat, overheated. Tried a 195* in standard rad but i think I added to much weep hole to it so no real help. I could watch the gauge rise and fall in cycles but it would get to what i called "run away" given enough time. Now Ive had a 205* stat with smaller hole in my car for 2 years, it was a cure unless on a long drive 45min+. Watched the gauge rise and fall to greater extent but the same end result. The ultimate cure was a the next size up radiator, greater exchange capacity as Ford saw fit to add as the minimum for a V8 in '67. So it cured what I called "run away." Over this winter the coldest i drove was in upper 40s. Just as long and maybe harder driving than past summers. Temps never got to 200*. I think my weep hole is too big. Next will be the 195* with a small or no bleed hole. Overall theory- less volume of water through the rad = lower temps top of engine thus cooler for a marginal system. The design of this system appears marginal and easily overwhelmed.

So if i am thinking wrongly please tell me,.there is a chance i am only wording it wrongly.
This singular "task" of the stat also has side affects to as you say, the volume of water. Would a greater volume came out at a lower or higher temp? Will the heat pulling capacity of the rad decrease or increase in relation to volume?


OP still can have a handful of tweaks needing done to help but I still maintain the lower temp stat, guessing its 180*, ain't helping. How is it not hurting if its marginal overall?
I will offer to send you a 195* if you will try it without changing anything else.
 

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Yes, @MrFlash and @vegasloki, but which is greater, the rates of the rad to remove or the engine to add heat? Wouldn't the radiator have a finite ability and a degrading ability at that to some point, to lower temps? Meaning that it might take 185* to 150* but will it take 200* to 150* in the same amount of time?
I'll toss an anecdote of my ongoing "science." Car came with a punched out stat, overheated. Tried a 195* in standard rad but i think I added to much weep hole to it so no real help. I could watch the gauge rise and fall in cycles but it would get to what i called "run away" given enough time. Now Ive had a 205* stat with smaller hole in my car for 2 years, it was a cure unless on a long drive 45min+. Watched the gauge rise and fall to greater extent but the same end result. The ultimate cure was a the next size up radiator, greater exchange capacity as Ford saw fit to add as the minimum for a V8 in '67. So it cured what I called "run away." Over this winter the coldest i drove was in upper 40s. Just as long and maybe harder driving than past summers. Temps never got to 200*. I think my weep hole is too big. Next will be the 195* with a small or no bleed hole. Overall theory- less volume of water through the rad = lower temps top of engine thus cooler for a marginal system. The design of this system appears marginal and easily overwhelmed.

So if i am thinking wrongly please tell me,.there is a chance i am only wording it wrongly.
This singular "task" of the stat also has side affects to as you say, the volume of water. Would a greater volume came out at a lower or higher temp? Will the heat pulling capacity of the rad decrease or increase in relation to volume?


OP still can have a handful of tweaks needing done to help but I still maintain the lower temp stat, guessing its 180*, ain't helping. How is it not hurting if its marginal overall?
I will offer to send you a 195* if you will try it without changing anything else.
I'm thinking there's another issue/problem with your engine. Generally closed-loop systems like our car's cooling systems will find a steady-state balance and stay there.
Note that as the water entering the radiator increases in temperature the radiator will transfer more heat to the air, and the water will drop more degrees in temperature as it passes through the radiator. This is the error in your previous math - "y" is not a fixed number but will increase as the temperature increases.
As has been said before, these cars did not overheat when they were new even with A/C, so if you have an overheating issue it usually means that one or more components in the entire system (engine and cooling) have started to fail or changes that you have made are over-taxing the system's capability.
 

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Um, late to the party? Forget about mine, I know theres problems like 50 year old engine scale and rust maybe even a clogged port somewhere. Yes I know that expression was not accurate just an illustration and yes as the water gets hotter the radiator removes more heat but only to a usefull point. And as for when new, no sheat Sherlock but how many '65-6 289s have temp control problems compared to '67 and up? WHAT DID FORD CHANGE?
Im still defending that with a low or no t-stat the temp can go higher with marginal radiators than with a higher temp stat..
 

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I'm enjoying this circulation flow conflict except that I don't have the smarts to compete with the engineering degrees with nothing other than a high school education, with 54 absences in one quarter because I'd rather work ay $3.00 am hour to make money to build my fake Shelby back in 1977. I wouldn't wish becoming a mechanic for a living on anybody but in order to become an automotive engineer you have to have an interest in cars. Which means your more likely to become a mechanic than an engineer. I'm already trying to figure out how to turn my little grandson into an engineer without him someday wanting to skip college and go straight to work as a mechanic like I did. Big mistake!!!!!!!

Here is a question for you guys. If you removed the thermostat would the increase in coolant flow allow the pump to create additional suction on the lower hose and have a greater chance of collapsing it without a spring?

I like Ford history. Here is a mistake Ford engineers made, not so much they made it as Henry insisted this was where he wanted "his" water pumps. When the flathead Ford was developed in 1932 they put the water pumps on top of the heads. That sucked the water out of the top of the engine instead of pushing it in through the bottom. That suction lowered the boiling point of the water in the block. They tried fan design changes, they added more louvers to the hood to let more heat out of the engine compartment. Finally in 1937 they moved the pumps to the block where it pushed the water in which created some pressure in there which raised the point the water turned to steam.

The first 1932 design sucked the water through the engine which lowered the boiling point. bad idea.



The second generation in 1937 moved the pumps to the block and sucked the water into the pump and then the pump sent it out under pressure into the block. That raised the boiling point which was a big improvement.
748064



They tweaked the cooling one last time from 1949 to 1953. They moved the upper radiator hoses to the front of the heads. Installed modern type thermostats instead of ones that clamped inside the hose and they redesigned how the coolant flowed through the block and head by changing the location of the holes and their sizes between the block and the heads and that upper hose outlet location. These cool better than the earlier versions.

748065



My Grandfather was steam Locomotive engineer. When I was kid he use gave me one those working steam stationary toy engines. Instead of playing video games I was lighting fires under a little copper boiler and waiting for it to create the steam to move the piston, rod and wheel. So at 12 year's old I was learning that when water turns to steam it expands by a volume of 1700 times. The incredible pressure explodes radiator hoses, rips apart solder joints in radiators and cracks blocks and heads.

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Back then we built model rockets and flew them, flew gas powered tether string airplanes, built kites out of sticks string and newspaper and flew them, built model cars and airplanes, erector sets and of course blew things up. Went out and shot our 22 rifles at 14. Learned about wind resistance and velocity effects on hitting the target. Junior high had wood shop, metal shop, ceramics even a rocket building class. High school had electronics and auto shop classes You spent most of your free times discovering how things worked. I beg kids now to get mechanical, electrical , materiel composite, chemistry or a civil engineering degree's. I ask them, don't you want to design and build stuff so that the nd of the day you can sit back and admire your work. Look forward to working on it the next day. I have not found one yet that wants to do any of that stuff anymore.

I better get going out to the garage and get a couple hours of work in or its going to be a bad day.
 

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Here is a question for you guys. If you removed the thermostat would the increase in coolant flow allow the pump to create additional suction on the lower hose and have a greater chance of collapsing it without a spring?
Lovin’ the pics and history. (y)

The removal of the thermostat wouldn’t cause the lower hose to collapse without the spring. The system is pressurized so that’s going to cause expansion rather than contraction. What can happen though is by changing the passage cavitation could be introduced. For those unfamiliar cavitation is a disruption in the stream that “churns”in more air when the pressure drops. Because the thermostat is a restriction even when fully open due to the housing or “skirt” in the flow of the circuit removing it can change the pressure. If it matters depends on the system. Removing it may or may not have an impact on the system. Many racers eliminate the thermostat by either punching out the spring and valve and using the housing or by making plates the size of the housing and running those in order to minimize the cavitation.

Over time cavitation will damage the impeller in the water pump. If you’ve looked at your pump impeller and it’s pitted and the edges are eaten away that’s cavitation. A damaged impeller will not flow the volume of coolant needed to meet the design of the system. Some cavitation will happen regardless but the more there is the more the pump impeller wears.
 

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Um, late to the party? Forget about mine, I know theres problems like 50 year old engine scale and rust maybe even a clogged port somewhere. Yes I know that expression was not accurate just an illustration and yes as the water gets hotter the radiator removes more heat but only to a usefull point. And as for when new, no sheat Sherlock but how many '65-6 289s have temp control problems compared to '67 and up? WHAT DID FORD CHANGE?
Im still defending that with a low or no t-stat the temp can go higher with marginal radiators than with a higher temp stat..
An engine that will overheat WITHOUT a thermostat is going to overheat WITH a thermostat.

The only time your "theory" is true is when the engine generates heat in excess of that which the cooling system can not properly dissipate. Even then, it's not a "hotter water in, hotter water out" scenario... it's a "so many BTU produced versus so many BTU dissipated". The net result is what determines, in an engine without a thermostat, the operating temperature. If the cooling system can dissipate more heat than the engine creates (this is the desired scenario...and the one for which the engineers have designed the cooling system to do) then the operating temperature will settle at a point which can be mathematically determined based on those factors. Thus, the reason why they put a thermostat in the system...to maintain a satisfactory temperature to have the engine run efficiently.

The old wives tale of "coolant traveling too fast" is just that.... in a closed system there is always "x" amount of surface area in constant contact with the coolant as well as "x" amount of surface area in constant contact with the heat producing aspect of the combustion process. Absorption of heat by a particular liquid in a closed system occurs over time whether or not that liquid is stationary or moving.

FWIW, I've owned 3 '65-66 Mustangs and none every had a cooling issue....nor did my '63 Fairlane, '66 Fairlane, '67 Cyclone, '70 Econoline, '70 Maverick, '71 LTD, or '80 F-250.... other than when I split a heater hose on the '66 Fairlane...... NOR did these cars overheat when new, even in the desert. The issue with heating problems in these cars is one of, or a combination of several of the following factors:

1. Poor quality or defective parts. This includes water pumps with poorly engineered and cheaply made impellers, radiators with insufficient fin count or poor design and construction, poor quality thermostats, etc.;

2. Improper component installation. This includes radiators spaced too close to air conditioning condensers, too far from the fan, fans with blade tips completely shrouded, "Cleveland" without the thermostat "plate", undersized crank or oversized water pump pulleys, missing DVCV's, Hot Idle Compensators, mismatched block/head steam holes, wrong or improperly installed head gaskets, wrong or improperly installed intake manifold gaskets (Windsors), excessive engine internal friction, too much quench/too little compression height piston leading to detonation, etc.;

3. Improper tuning/adjustment. This includes excessively lean fuel mixtures, too much valve preload, not enough spark advance, excessive exhaust restrictions, etc.;

Performance engines don't always run hotter than stock engines... what they DO produce for extra heat is, if the engine is efficient, is convert more of that heat into motion, exhausting the excess.
 

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An engine that will overheat WITHOUT a thermostat is going to overheat WITH a thermostat.
NOPE, I think you contradict yourself below.

The only time your "theory" is true is when the engine generates heat in excess of that which the cooling system can not properly dissipate. <<THIS IS THE RUB AND WHAT CAN HAPPEN! AND I ACCEPTED IS HAPPENING TO ME. AND IS SUBJECT TO WHAT THE OP IS EXPERIENCING Even then, it's not a "hotter water in, hotter water out" scenario... it's a "so many BTU produced versus so many BTU dissipated". THATS BS SEMANTICS> THATS WHY I ASKED "Would a greater volume come out at a lower or higher temp? Will the heat pulling capacity of the rad decrease or increase in relation to volume? "The net result is what determines, YES, THE NET SEE MY POOR EQAUTION ABOVE in an engine without a thermostat, the operating temperature. YES, SAME AS A LOW STAT THAT IS WIDE OPEN EARLY Thus, the reason why they put a thermostat in the system...to maintain a satisfactory temperature to have the engine run efficiently. WE CAN AGREE THE STAT IS TO RAISE THE TEMP TO A POINT THEN STOP THE RISE

The old wives tale of "coolant traveling too fast" is just that.... in a closed system there is always "x" amount of surface area in constant contact with the coolant as well as "x" amount of surface area in constant contact with the heat producing aspect of the combustion process. YOU ASSUME THESE ARE EQUAL? THAT THE ENGINE IS ADDING HEAT AT THE SAME RATE THE RAD IS TAKING IT AWAY Absorption of heat by a particular liquid in a closed system occurs over time whether or not that liquid is stationary or moving. TIME, YES TIME! AND YOUR CONTRADICTION THAT IGNORES THE TIME IN COOLING. I THINK I"M BUYING WHAT @VEGASLOKI SAYS AS "ITS THE VOLUME." THUS THE QUESTIONS ABOVE. HOT IN AT LOW VOLUME OUT EQUALS MORE OR LESS COMPARED TO HOT IN HIGH VOLUME OUT? OR< maybe another version, Will increased heat in benefit from lower volume? which I am translating as more time in rad.

FWIW, I've owned 3 '65-66 Mustangs and none every had a cooling issue....nor did my '63 Fairlane, '66 Fairlane, '67 Cyclone, '70 Econoline, '70 Maverick, '71 LTD, or '80 F-250.... other than when I split a heater hose on the '66 Fairlane...... NOR did these cars overheat when new, even in the desert. The issue with heating problems in these cars is one of, or a combination of several of the following factors: JUST LIKE THE OP DIDN"T SAY OVER HEAT NEITHER AM I, I SAID 200* WASNT OVER HEATING. FOR ABOUT THE FOURTH TIME, MERELY HOTTER! AND MORE TIME TO COOL AS A VOLUME IN THE RAD MAKES FOR A LONGER TRIP IN TIME TO THE HIGHER TEMP IN THE ENGINE.
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..
 

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Disclaimer: I have an ME degree and agree with more flow =more cooling camp
I and a friend were both having overheating at speed problems in two different vehicles.
He had a GT350 Mustang that he vintage raced. He was blowing coolant past the radiator cap part way through a race.
I have a Sunbeam Tiger with a 260 Small block Ford engine. At freeway speeds or on hill the temp would rise to 230F plus. The Tiger could idle in a garage for over an hour and the temp was stable at 210F. This on a day when it was 103F in the garage. I had replace a blown head gasket, new radiator, thermostat etc.
I replaced the water pump with an Edelbrock high flow pump. Immediately the temps were stable at 210 max on the freeway or hill climbing. This was close to 15 years ago and the car still runs at the same temps as it did the day I changed the pump.
Upon hearing my results, my vintage race buddy installed an Edelbrock pump and his overheating problem on the racetrack stopped. Period full stop.
So, the theory makes sense to my engineering mind and my experience with a high flow pump backs up the theory.
Make use of my story or not, it matters not to me.
 

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@Asm109 --- Could it be that the pumps you both had were starting to have impeller issues and putting NEW pumps on fixed that OR was it the fact you put high flow pumps on ? That is the problem with ALL these types of conversations--- Replacing a problem part with a new part fixed the issue (or covered up the real problem) without knowing for certain if the high flow pump OR a regular pump would have done the same job.
 

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Disclaimer: I have an ME degree and agree with more flow =more cooling camp
I and a friend were both having overheating at speed problems in two different vehicles.
He had a GT350 Mustang that he vintage raced. He was blowing coolant past the radiator cap part way through a race.
I have a Sunbeam Tiger with a 260 Small block Ford engine. At freeway speeds or on hill the temp would rise to 230F plus. The Tiger could idle in a garage for over an hour and the temp was stable at 210F. This on a day when it was 103F in the garage. I had replace a blown head gasket, new radiator, thermostat etc.
I replaced the water pump with an Edelbrock high flow pump. Immediately the temps were stable at 210 max on the freeway or hill climbing. This was close to 15 years ago and the car still runs at the same temps as it did the day I changed the pump.
Upon hearing my results, my vintage race buddy installed an Edelbrock pump and his overheating problem on the racetrack stopped. Period full stop.
So, the theory makes sense to my engineering mind and my experience with a high flow pump backs up the theory.
Make use of my story or not, it matters not to me.
In my two posts I said: “a high-volume water pump is rarely necessary” and “if you have an overheating issue it usually means that one or more components in the entire system (engine and cooling) have started to fail or changes that you have made are over-taxing the system's capability.” Both your examples actually prove my point as you were over-taxing the system as designed.
In both your examples you were dealing with an older car, thus possibly many components were subpar. Racing a GT350 really exceeds its design parameters (it was still a Mustang at heart) unless the cooling system was upgraded (which is what you did). And judging from my Tiger anything on the highway exceeded its design (I had a thick folder of articles detailing how to fix all the short-comings of the car; only the folder for my Europa TC was thicker). So, in both cases you improved on an inadequate or deficient system.
Not saying that you did, but many heating problem posts evidence people putting upgraded water pumps and radiators and new thermostats in cars that have other underlying issues.
And yes, as an ME you know that increasing the fluid flow will increase the system’s ability to dissipate heat. In most cases, however, it simply isn’t necessary.
IMHO, for all those putting in “mildly built” or stroker engine with a cooling system not doing its job, it simple needs a good 2-row aluminum radiator w/ stock fan and shroud.
 

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Disclaimer: I have an ME degree and agree with more flow =more cooling camp
I and a friend were both having overheating at speed problems in two different vehicles.
He had a GT350 Mustang that he vintage raced. He was blowing coolant past the radiator cap part way through a race.
I have a Sunbeam Tiger with a 260 Small block Ford engine. At freeway speeds or on hill the temp would rise to 230F plus. The Tiger could idle in a garage for over an hour and the temp was stable at 210F. This on a day when it was 103F in the garage. I had replace a blown head gasket, new radiator, thermostat etc.
I replaced the water pump with an Edelbrock high flow pump. Immediately the temps were stable at 210 max on the freeway or hill climbing. This was close to 15 years ago and the car still runs at the same temps as it did the day I changed the pump.
Upon hearing my results, my vintage race buddy installed an Edelbrock pump and his overheating problem on the racetrack stopped. Period full stop.
So, the theory makes sense to my engineering mind and my experience with a high flow pump backs up the theory.
Make use of my story or not, it matters not to me.
What is typically the case with a "high flow" pump helping with overheating is usually the result of increased PRESSURE which not only raises the boiling point of the coolant but also helps reduce the formation of steam pockets. Regardless of how "high flow" your water pump might be, the flow through the system is limited by the smallest opening the coolant must pass through which, when you measure surface area, would most likely be a toss-up between the thermostat and bypass or the 2 water passages exiting at the front of the cylinder heads.

In the vast majority of cases that I've seen over the past 40+ years the resolution of cooling system issues hasn't been the result of some "magical" part replacement other than it replaced something that wasn't performing properly in the first place, either through design or condition.
 
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