To thermostat or not to thermostat (1 Viewer)

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Joined
Nov 28, 2019
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Location
Houston, TX
I am wondering if I should put my theromostat in and would like some opinions.

I currently run no thermostat and have overheating issues when I go above 60mph. Have a 1969 1F engine. Since I live in Texas and it is real hot all the time, I figured if I don’t have the thermostat in I will have nothing slowing down / inhibiting water flow and have increased cooling efficiency. I have burped the system a number of times and water temp still likes to climb (even had 1 over heat).

So, should I 1) put it in because I am a dumbass for not having it in or 2) should I keep running without it and a pro radiator flush or possible new radiator or ???.
 
Put it back in and find the actual problem that is causing your rig to overheat.

That's my 2 cents.
 
Flush your radiator and block, check the inside of your radiator to see if it is totally clogged. How's your water pump?
Does the fan work like it's supposed to?
 
Flush your radiator and block, check the inside of your radiator to see if it is totally clogged. How's your water pump?
Does the fan work like it's supposed to?
To add to these, make sure your timing is set at least in the ballpark of correct and that your carburetor isn't running really lean.
 
Flush your radiator and block, check the inside of your radiator to see if it is totally clogged. How's your water pump?
Does the fan work like it's supposed to?

I should have mentioned before that I have already replaced the fan we a new racer city plastic fan (clutchless), new water pump, and flushed the block.

To add to these, make sure your timing is set at least in the ballpark of correct and that your carburetor isn't running really lean.

Will do.
 
To check for clogs in your radiator get a spray bottle filled with cool/cold water. Get the engine good and hot and then spray the cool/cold water onto the radiator. You'll be able to tell if there are clogged spots in the radiator by how quickly the water evaporates, or doesn't.
 
there is no good reason to not run a thermostat long term. engines are designed to run in a certain temp range for a reason, running one cold isnt doing it any favors.
 
Also, the thermostats on these rigs don’t just open and close. They also control a bypass function. When the T-stat closes, it opens a bypass at the same time. That’s the little hose running from the water pump to the T-stat housing. When the T-stat opens, it also closes off the bypass so ALL the coolant being pumped circulates between the engine and radiator. Without a T-stat the bypass is always open, and a portion of the water gets bypassed.
 
I would drive a 45 in southwest Asia and it got significantly warmer there than in Texas and never had a problem with overheating. You have other problems that need to be resolved. I would answer yes to question 1 and the last half of question 2. Be methodical in your efforts.:bounce:
 
I'm an advocate for a fresh radiator; it is dollars well spent. But, I had to learn the hard way. The new radiator is best with the original fan shroud.

This is what I would do. A few Mudders have diagnosed their engines with infrared thermometers. I'd do this route because it is smarter than turning wrenches, but I've never had an overheating problem on an vehicle that I worked on, so I'm not an expert.

Then, drain both the radiator and block; empty and clean overflow tank. Remove the lower radiator hose. If your not too crusty, then flush with distilled water. It is inexpensive, but tap water is cheap, and I don't trust all the chlorine, chloramines, and dissolved minerals in tap water. Then, install a new radiator, and the thermostat.

If the engine (by that I mean the area around the temp sender unit) is still cooking, and all the cooling components are deemed okay, then I'd personally, pull the head and see what and where things are obstructed.
 
I currently run no thermostat and have overheating issues when I go above 60mph. Have a 1969 1F engine. Since I live in Texas and it is real hot all the time, I figured if I don’t have the thermostat in I will have nothing slowing down / inhibiting water flow and have increased cooling efficiency. I have burped the system a number of times and water temp still likes to climb (even had 1 over heat).

your thinking is flawed. the water flow needs restricted in order to slow the flow down so it can pick the heat up.
 
And the coolant’s heat needs time to dissipate through the radiator fins. But if it’s moving constantly it’s just recycling ever-warming coolant.
 
I probably should leave this alone but, this is a topic that has been debated forever, and I believe will never get settled. There is so much info out there from supposed experts that have totally opposite theories and opinions. You can take your pick but getting to the truth ain’t so easy. Respectfully I do not agree with the “Flowing too fast to cool” theory.

I first heard of it from my dad when I was 8 or 9 years old (in the late 50s. He routinely built up Ford flatheads for stock cars that my uncle drove at a local racetrack in South Jersey. All the flatheads at the track ran without thermostats but placed flat washers in there of specific size to slow down the flow and overheating was prevented.

However, decades later I learned that those cooling systems were open to the atmosphere and non-pressurized. What was happening was, the restrictor washer raised the pressure inside the engine which in turn raised the boiling point and the coolant flashing to steam was prevented. With the engines running at high rpm the flow rate decrease was negligible if any. There are those who claim that this practice helped begin the theory that slower flow is better.
 
To back up Steamer's point, the radiator and engine don't know how fast the coolant is moving. Heat is transferred by photons.
More of the photons move at the speed of light from an area of higher heat to an area of less heat. About the only thing that can
interrupt that effect is an insulating layer of air or vapor. The turbulence from faster flow ought to minimize this.
 
I have never seen the “flowing too fast to cool” theory demonstrated in any accurate or controlled comparison. My friend of a few decades who has done a lot of drag car, and swamp buggy building supports this theory and we often get in long heated debates over it. Not long ago I had a chance to test his theory while doing some flushing on my F.5.

To do a thorough flush with a garden hose in the radiator and the block and radiator drains open, the thermostat will not open with the steady flow of fresh water coming in, so I removed it. To block off the bypass I tapped and plugged a spare housing top and put the bypass hose back on. This way I got full flow through the engine & rad with nothing bypassing and no restriction from the thermostat. In his theory, without the restriction of the thermostat, I would not be cooling as well.

To test my friend’s theory, I got it up to a steady temperature and then restricted the flow by various amounts with a simple clamp on the hose only inches downstream from the T-stat housing. I went back and forth from restricted to non-restricted. I also had thermocouples going to a pair of Fluke meters on the inlet and outlet of the radiator. The Fluke readings and the dash mount VDO mechanical temp gauge all responded the same to the restriction change. Temps went up with more restriction and came down when the restriction was removed. This was no quickie test. It went on for hours leaving it run at a steady rpm both ways while I did other chores.

My friend still believes in his theory and that my test was an unexplained phenomenon. We're still friends but just don't discuss it anymore.

BypassPlug.jpg


Hose Squeeze.jpg
 
To back up Steamer's point, the radiator and engine don't know how fast the coolant is moving. Heat is transferred by photons.
More of the photons move at the speed of light from an area of higher heat to an area of less heat. About the only thing that can
interrupt that effect is an insulating layer of air or vapor. The turbulence from faster flow ought to minimize this.
I think you are confusing radiant vs conduction. A liquid cooled engine is definitely utilizing conduction not radiant thermal transference.
 
Without expert analysis from HaryV this discussion is pointless.
 
I think you are confusing radiant vs conduction. A liquid cooled engine is definitely utilizing conduction not radiant thermal transference.
Heat is energy and and is transferred by photons. AFAIK there is no other way energy gets from one place to another, conduction included.
However, I am not a physicist and I'm willing to hear from anyone who is informed on this subject. :)

The way I see it, and how it is pertinent to this thread, is that the exchange of heat happens in such a way that as the speed of the coolant
through the engine and cooling system increases there is no logical way it will reduce that exchange.
 
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