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  #1  
Old 08-12-2010
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Thermostat Myth

I had to replace my radiator last Monday, due to a "drip" coming from the core to tank seal. The system was clean, but I always do a distilled water FLUSH (about 10 gallons) running the engine without a thermostat to get the most flow through the system, before replacing the thermostat. It was in the mid 90's, so I thought I would prove (or disprove) the myth about an engine overheating without a thermostat. I drove it about an hour at highway speeds, and stop and go city traffic, and the temp gauge never got above the bar on C. (red circle in the photo below. This photo is a previous photo of the instrument panel):





The myth was disproved, no overheating without a thermostat!
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  #2  
Old 08-12-2010
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the reason for a thermostat is to close and keep the engine at optimum running temperature with out one there of coarse it wont over heat....
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Old 08-12-2010
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A few years ago, I had a heated technical debate with Rich (wydopnthrtl), where he claimed the thermostat had to close to allow the coolant to cool in the radiator. (post # 7 in this thread):

https://www.ranger-forums.com/f18/e-...heating-67079/

Of course, looking back, I was wrong where I stated that an engine would overheat without a thermostat (post #13), but
I knew that Rich's post was totally wrong!
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  #4  
Old 08-12-2010
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I never knew people thought that?

Now if the thermo sticks closed then ya it will overheat.
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Old 08-12-2010
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or stick open and never over heat lol.....
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  #6  
Old 08-12-2010
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I never knew people thought that?

Now if the thermo sticks closed then ya it will overheat.

Pretty incredible, eh? And this guy claimed to be a ME. However, he also owned a Cadillac, which told a lot!
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  #7  
Old 08-12-2010
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or stick open and never over heat lol.....
I had that problem with my GEO. When ever I stopped at a stop sign it would heat up and give me a few seconds of heat. When I would take off it would get freezing cold again.
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  #8  
Old 08-12-2010
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I had that problem with my GEO. When ever I stopped at a stop sign it would heat up and give me a few seconds of heat. When I would take off it would get freezing cold again.
i had that problem too but mine would never heat up lol
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  #9  
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Exactly! Contrary to Rich's understanding of thermostat operation (has to close to cool off) a thermostat closes to
heat up!
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  #10  
Old 08-12-2010
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Originally Posted by Takeda View Post
Exactly! Contrary to Rich's understanding of thermostat operation (has to close to cool off) a thermostat closes to
heat up!
exactly, A lot of derby car guys take them out to run as cool as possible and to never have a issue with it sticking.
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Old 08-12-2010
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It will overheat after time. I still believe that. It just takes a really long time and the correct conditions.

A ford procedure for flushing the cooling system is to remove the t-stats and run the truck for 1 hour at 2000 rpms, I am here to tell you after an hour of it sitting still the temps really start to move up there. Thus it will overheat in time. Rich's theory can be proved, in this case if the tstat closed the water in the radiator would get colder than if the tstat stayed open. air would be passing by it longer before it moved out the radiator.
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Old 08-12-2010
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Originally Posted by zabeard View Post
It will overheat after time. I still believe that. It just takes a really long time and the correct conditions.

A ford procedure for flushing the cooling system is to remove the t-stats and run the truck for 1 hour at 2000 rpms, I am here to tell you after an hour of it sitting still the temps really start to move up there. Thus it will overheat in time. Rich's theory can be proved, in this case if the tstat closed the water in the radiator would get colder than if the tstat stayed open. air would be passing by it longer before it moved out the radiator.
Yeah but in that procedure I'll bet the truck is stationary right? Moving down the road, even in 95* heat, it wouldn't overheat.

I thought it was common sense I guess... without a thermostat you'll likely never get up to optimal operating temperature, assuming normal driving conditions. This is the same as the T-Stat stuck open.

With the T-Stat stuck closed, yeah it's real easy to overheat.

The thermostat on my truck was stuck open last summer and never got up to temp. Replaced it, truck operates at a more optimal temperature, and I picked up some better fuel mileage as well.
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Old 08-12-2010
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This is not for Bob.. just for the rest of you with a brain.


I was not only a ME.. but a cooling engineer for ford for 6 yrs. Here is my input. Take it or leave it.. or you can be like Bob and go with your preconcieved notions that I'm full of xxxx Hey.. what ever floats you boat is ok with me. ;-)



The cooling system in a car/truck does two things.
1) It warms the engine as quick as is possible for both comfort and for reducing emissions. It does this by having the stat closed and recirculating coolant through the heater core.

2) Once up to full temp.. it provides on avg 40% of the engines cooling needs. Another 40% goes out the exhaust and 20% simply disipates into the engine room & tranny casting.

Here is the point which Bob willfully ignores... **on modern cars** the radiator volume is decreasing all the time. There are several reasons.. weight = mpg costs, more efficiency requires less fluid, and cost to produce smaller parts is lower.

Here is a mental example to help understand the point.. If a guy took the stat out of an typical ranger engine.. and made a 60x60, 10 core thick, aluminum radiator.. it would over cool the engine and never heat up to normal operating temps. Now if a guy made a 2x2, 1 core thick, steel radiator the engine would have inadequate cooling and over heat very quickly.

So.. the balance we OEM engineers try to shoot for is to understand where & how the car/truck will be used. (Alaska & the desert types of climates) Each OEM has their own standards that they design each platform to. Trucks always are expected to tow in hot climates and so they always have larger than car type of radiators.
We design (and test) them for the intended situation. For pickups this often results in cooling systems that are larger than the avg guy will ever need.
Point being.. the stat in a ford pu **for the most part** will remain mostly closed or to keep the engine up to operation temp.

Now Bob might kick and scream like a little child about what I say. And he might try to distort my words (watch for him taking things out of context)...this is simple thermodynamics. Again for those of you with a brain.. look at the example I give of two different radiator sizes and you'll understand the point I'm trying to make.

The stat needs to stay close to closed to keep the engine at the proper operating temp. (which is usually about 10-12F hotter than the stat is rated for)



Regards,
Rich
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  #14  
Old 08-12-2010
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Quote:
Originally Posted by zabeard View Post
It will overheat after time. I still believe that. It just takes a really long time and the correct conditions.

A ford procedure for flushing the cooling system is to remove the t-stats and run the truck for 1 hour at 2000 rpms, I am here to tell you after an hour of it sitting still the temps really start to move up there. Thus it will overheat in time. Rich's theory can be proved, in this case if the tstat closed the water in the radiator would get colder than if the tstat stayed open. air would be passing by it longer before it moved out the radiator.
You are right, but have you ever heard of it happening? There would have to be a load on the engine and idling for a extreme amount for time like you stated above.

A closed thermo stat will cause the engine to overheat

A open thermo stat "could" cause the engine to overheat but it would probably need a big load at a slow speed for a long period of time.

Its highly unlikely of it ever happening on a normal vehicle.
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  #15  
Old 08-12-2010
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Quote:
Originally Posted by wydopnthrtl View Post
This is not for Bob.. just for the rest of you with a brain.


I was not only a ME.. but a cooling engineer for ford for 6 yrs. Here is my input. Take it or leave it.. or you can be like Bob and go with your preconcieved notions that I'm full of xxxx Hey.. what ever floats you boat is ok with me. ;-)



The cooling system in a car/truck does two things.
1) It warms the engine as quick as is possible for both comfort and for reducing emissions. It does this by having the stat closed and recirculating coolant through the heater core.

2) Once up to full temp.. it provides on avg 40% of the engines cooling needs. Another 40% goes out the exhaust and 20% simply disipates into the engine room & tranny casting.

Here is the point which Bob willfully ignores... **on modern cars** the radiator volume is decreasing all the time. There are several reasons.. weight = mpg costs, more efficiency requires less fluid, and cost to produce smaller parts is lower.

Here is a mental example to help understand the point.. If a guy took the stat out of an typical ranger engine.. and made a 60x60, 10 core thick, aluminum radiator.. it would over cool the engine and never heat up to normal operating temps. Now if a guy made a 2x2, 1 core thick, steel radiator the engine would have inadequate cooling and over heat very quickly.

So.. the balance we OEM engineers try to shoot for is to understand where & how the car/truck will be used. (Alaska & the desert types of climates) Each OEM has their own standards that they design each platform to. Trucks always are expected to tow in hot climates and so they always have larger than car type of radiators.
We design (and test) them for the intended situation. For pickups this often results in cooling systems that are larger than the avg guy will ever need.
Point being.. the stat in a ford pu **for the most part** will remain mostly closed or to keep the engine up to operation temp.

Now Bob might kick and scream like a little child about what I say. And he might try to distort my words (watch for him taking things out of context)...this is simple thermodynamics. Again for those of you with a brain.. look at the example I give of two different radiator sizes and you'll understand the point I'm trying to make.

The stat needs to stay close to closed to keep the engine at the proper operating temp. (which is usually about 10-12F hotter than the stat is rated for)



Regards,
Rich
Obviously you don't know wtf ur talking about. I drove with my thermostat off for an hour and this is much more research than your so-called "6 years of ford cooling engineer" experience.
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  #16  
Old 08-12-2010
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Quote:
Originally Posted by wydopnthrtl View Post
This is not for Bob.. just for the rest of you with a brain.


I was not only a ME.. but a cooling engineer for ford for 6 yrs. Here is my input. Take it or leave it.. or you can be like Bob and go with your preconcieved notions that I'm full of xxxx Hey.. what ever floats you boat is ok with me. ;-)



The cooling system in a car/truck does two things.
1) It warms the engine as quick as is possible for both comfort and for reducing emissions. It does this by having the stat closed and recirculating coolant through the heater core.

2) Once up to full temp.. it provides on avg 40% of the engines cooling needs. Another 40% goes out the exhaust and 20% simply disipates into the engine room & tranny casting.

Here is the point which Bob willfully ignores... **on modern cars** the radiator volume is decreasing all the time. There are several reasons.. weight = mpg costs, more efficiency requires less fluid, and cost to produce smaller parts is lower.

Here is a mental example to help understand the point.. If a guy took the stat out of an typical ranger engine.. and made a 60x60, 10 core thick, aluminum radiator.. it would over cool the engine and never heat up to normal operating temps. Now if a guy made a 2x2, 1 core thick, steel radiator the engine would have inadequate cooling and over heat very quickly.

So.. the balance we OEM engineers try to shoot for is to understand where & how the car/truck will be used. (Alaska & the desert types of climates) Each OEM has their own standards that they design each platform to. Trucks always are expected to tow in hot climates and so they always have larger than car type of radiators.
We design (and test) them for the intended situation. For pickups this often results in cooling systems that are larger than the avg guy will ever need.
Point being.. the stat in a ford pu **for the most part** will remain mostly closed or to keep the engine up to operation temp.

Now Bob might kick and scream like a little child about what I say. And he might try to distort my words (watch for him taking things out of context)...this is simple thermodynamics. Again for those of you with a brain.. look at the example I give of two different radiator sizes and you'll understand the point I'm trying to make.

The stat needs to stay close to closed to keep the engine at the proper operating temp. (which is usually about 10-12F hotter than the stat is rated for)



Regards,
Rich
You are right, but from reading your post its not going to happen unless you use a super small radiator.

A normal vehicle its not going to happen with a t-stat stuck open.
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  #17  
Old 08-12-2010
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Quote:
Originally Posted by Red_Ak_Ranger View Post
Obviously you don't know wtf ur talking about. I drove with my thermostat off for an hour and this is much more research than your so-called "6 years of ford cooling engineer" experience.
I drove for 2 weeks in a GEO with a super small radiator with a stuck open T-Stat. 30 miles each way. Never had a issue with the car over heating.

Now "maybe" If I left the car in neutral and let it rev to 5k and sit there with no air movement it "might" start to get hot after some time. But that would happen if I had a T-Stat too!
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  #18  
Old 08-12-2010
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Quote:
Originally Posted by wydopnthrtl View Post
This is not for Bob.. just for the rest of you with a brain.


I was not only a ME.. but a cooling engineer for ford for 6 yrs. Here is my input. Take it or leave it.. or you can be like Bob and go with your preconcieved notions that I'm full of xxxx Hey.. what ever floats you boat is ok with me. ;-)



The cooling system in a car/truck does two things.
1) It warms the engine as quick as is possible for both comfort and for reducing emissions. It does this by having the stat closed and recirculating coolant through the heater core.

2) Once up to full temp.. it provides on avg 40% of the engines cooling needs. Another 40% goes out the exhaust and 20% simply disipates into the engine room & tranny casting.

Here is the point which Bob willfully ignores... **on modern cars** the radiator volume is decreasing all the time. There are several reasons.. weight = mpg costs, more efficiency requires less fluid, and cost to produce smaller parts is lower.

Here is a mental example to help understand the point.. If a guy took the stat out of an typical ranger engine.. and made a 60x60, 10 core thick, aluminum radiator.. it would over cool the engine and never heat up to normal operating temps. Now if a guy made a 2x2, 1 core thick, steel radiator the engine would have inadequate cooling and over heat very quickly.

So.. the balance we OEM engineers try to shoot for is to understand where & how the car/truck will be used. (Alaska & the desert types of climates) Each OEM has their own standards that they design each platform to. Trucks always are expected to tow in hot climates and so they always have larger than car type of radiators.
We design (and test) them for the intended situation. For pickups this often results in cooling systems that are larger than the avg guy will ever need.
Point being.. the stat in a ford pu **for the most part** will remain mostly closed or to keep the engine up to operation temp.

Now Bob might kick and scream like a little child about what I say. And he might try to distort my words (watch for him taking things out of context)...this is simple thermodynamics. Again for those of you with a brain.. look at the example I give of two different radiator sizes and you'll understand the point I'm trying to make.

The stat needs to stay close to closed to keep the engine at the proper operating temp. (which is usually about 10-12F hotter than the stat is rated for)



Regards,
Rich






Rich, for the last time, try to understand this concept:

A thermostat CLOSES to HEAT, and OPENS to COOL.......

Very simple!!!

And Rich your statement here:

It does this by having the stat closed and recirculating coolant through the heater core.

This does not happen in the summer when the heater isn't used. The heater control valve keeps coolant from going through the heater core. The coolant is circulated in the block via a bypass hose until the thermostat opens........

Last edited by Takeda; 08-12-2010 at 11:21 AM.
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  #19  
Old 08-12-2010
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Ehh, i didn't understand the argument til i read up on thermostats....

http://auto.howstuffworks.com/question248.htm
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  #20  
Old 08-12-2010
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Originally Posted by zabeard View Post
It will overheat after time. I still believe that. It just takes a really long time and the correct conditions.

A ford procedure for flushing the cooling system is to remove the t-stats and run the truck for 1 hour at 2000 rpms, I am here to tell you after an hour of it sitting still the temps really start to move up there. Thus it will overheat in time. Rich's theory can be proved, in this case if the tstat closed the water in the radiator would get colder than if the tstat stayed open. air would be passing by it longer before it moved out the radiator.

Zach, think about it, what would make the thermostat close? Hint: A thermostat CLOSES to HEAT, OPENS to COOL

The thermostat would close if the coolant going to the radiator was TOO COOL, not TOO HOT.
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  #21  
Old 08-12-2010
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Takeda,

I think what there saying is without a T-Stats you can have TOO MUCH flow thus the coolant is not in the radiator long enough to cool off before entering the engine.

Lets say you have a T-stat - Water comes out of the engine at 200 degress, goes into the radiator and sits in there 2 mins and comes out 150 degrees. (just making up numbers)

Lets say you take the T-Stat off - Water goes in at 200 degrees and goes into the radiator but only sits in there 30 secs, so it goes back into the engine at 190 degrees. Eventually the engine will keep rising and the rad can't keep up.

Now when you remove the T-stat this is what normally happends

Water goes into the radiator at 160 degrees stays in the rad 30 secs and comes out 150. 90% of the time the coolant is not in the engine long enough to heat up the coolant to 200 degrees.

It would have to be a perfect scenario to over heat a engine without a Tstat

Hope that makes since
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  #22  
Old 08-12-2010
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Originally Posted by JoshK View Post
Takeda,

I think what there saying is without a T-Stats you can have TOO MUCH flow thus the coolant is not in the radiator long enough to cool off before entering the engine.

Lets say you have a T-stat - Water comes out of the engine at 200 degress, goes into the radiator and sits in there 2 mins and comes out 150 degrees. (just making up numbers)

Lets say you take the T-Stat off - Water goes in at 200 degrees and goes into the radiator but only sits in there 30 secs, so it goes back into the engine at 190 degrees. Eventually the engine will keep rising and the rad can't keep up.

Now when you remove the T-stat this is what normally happends

Water goes into the radiator at 160 degrees stays in the rad 30 secs and comes out 150. 90% of the time the coolant is not in the engine long enough to heat up the coolant to 200 degrees.

It would have to be a perfect scenario to over heat a engine without a Tstat

Hope that makes since
I understand that scenario, but I didn't see it when I ran without a thermostat.

Rich thinks that the thermostat has to close, to allow the coolant to cool in the radiator, which isn't the case. Just the restriction of the thermostat body when the thermostat is open allows enough restriction for the coolant to cool in the radiator. I'm sure a "stuck open" thermostat has never caused overheating!
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  #23  
Old 08-12-2010
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Originally Posted by Takeda View Post
I understand that scenario, but I didn't see it when I ran without a thermostat.

Rich thinks that the thermostat has to close, to allow the coolant to cool in the radiator, which isn't the case. Just the restriction of the thermostat body when the thermostat is open allows enough restriction for the coolant to cool in the radiator. I'm sure a "stuck open" thermostat has never caused overheating!
I have never ever heard of it happening like you said.

It would have to be the perfect scenario or a super super small radiator on the car.
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  #24  
Old 08-12-2010
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I have never ever heard of it happening like you said.

It would have to be the perfect scenario or a super super small radiator on the car.
Another possibility would be for the water pump to cavitate easier without the thermostat. But, I would probably have to run the engine at 5000 RPMs continuously for that to happen.
And if this happened, it would cause too little coolant flow into the radiator, not too fast of a flow.

Last edited by Takeda; 08-12-2010 at 12:30 PM.
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  #25  
Old 08-12-2010
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How stupid is this thread? We have 2 grown men arguing over the operation of a thermostat, and one of them acting extremely... juvenile.

Move on and get over it.

Bob, Rich has already acknowledged that a thermostat needs to stay closed to keep the vehicle at optimum operating temp. What more do you want? He is absolutely correct. IF the thermostat was to stay open, or non-existant in the cooling system, the vehicle would likely never reach operating temp. What else are you trying to argue about? From the confrontational vibe of your posts ("Rich this, Rich that"), it seems you're just fishing for drama.

I like the photos you post Bob (or used to post, have not seen any recently but I have not been online much). Apparently you hold a grudge against Rich for whatever was argued about before. Maybe it's time to get over that, or keep it to yourself?
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