the thermostats purpose is to hold back water long enough for the radiator to radiate the heat off the coolant just cycled from the block, once the temp of the coolant in the engine gets to the thermostats opening temp it opens and the cycle starts over. If there`s no thermostat the coolant can flow too quickly causing the engine to overheat since the radiator won`t have time to radiate enough heat to properly cool it.

 

the thermostats purpose is to hold back water long enough for the radiator to radiate the heat off the coolant just cycled from the block, once the temp of the coolant in the engine gets to the thermostats opening temp it opens and the cycle starts over. If there`s no thermostat the coolant can flow too quickly causing the engine to overheat since the radiator won`t have time to radiate enough heat to properly cool it.

If the water stays in the radiator longer to get rid of more heat, isn't it also staying in the engine longer and building more heat? Flow Cooler water pumps claim a temp. reduction by circulating water faster.
A computer controlled engine will run very poorly without a thermostat.
Bob

 

I was under the same impression as Bob C. and my engine is a 70 non computer controlled engine, so thats not an issue.

 

The cooling system is designed to be able to keep the engine temperature within an optimal operating range regardless of temperature and conditions. In other words, the system is designed large enough for "worse case" operation. In that "worse case" situation, the thermostat would be fully open.

The thermostat works from both ends to keep the engine temperature within operating range.

On the cold side, the thermostat keeps the coolant inside the engine when engine temp is below the optimum operating range so that the engine temperature quickly rises to within its optimum range.

On the hot side, the thermostat regulates the amount of coolant to the radiator so that as much heat as is required is released to the outside air to keep the engine from overheating, but not so much that the engine temp drops below the desired operating range.


If you don't have a thermostat, and assuming the the cooling system is working properly and sized properly, the engine will nearly always operate at well below its optimal range, unless its under heavy load on a hot day. Having an engine too cold is almost as bad as an engine too hot.


Think of the furnace in your house (use A/C if you live in a warm area). Its big enough to keep the house at say 68 degrees, during the worst cold snap you'd expect in your area, which might be 10 below zero. If you run that furnace continuously when its 60 degrees outside, your house is going to be well above 68 in short order.

On the other hand, when its 40 degrees and you turn on the furnace for the first time, you want it to run continuously up until the house is at 68, then you want the heat regulated so it doesn't go over that.

The thermostat in your house does the same thing that the thermostat in your car's cooling system.

 

Whether a thermostat is required depends on a number of issues:

1. Is you car computer controlled? If no, see #2. If yes, then you need the engine to reach the proper temperature so the engine management system leans out the fuel mixture.

2. Is the climate in your area cold? If no, see #3. If yes, then having a thermostat helps the engine to get rid of deposits that can cause sludge to form in the crankcase.

3. Take an old thermostat and removethe temperature sensing element, the spring and so on so that you end up with a disk of metal with a hole in the middle. Put the disk in the thermostat housing just like it was a thermostat. It will slow the flow of coolant through the system to allow the cooling system to do its job.

Cheers

 

I have heard people say u need a thermostat for keeping water in the radiator longer to cool down, personally I think its more of a myth, not sure if it is true or not but they never made a difference with any of my non-computer cars.

 

I have heard people say u need a thermostat for keeping water in the radiator longer to cool down, personally I think its more of a myth, not sure if it is true or not but they never made a difference with any of my non-computer cars.

I'm with you on this.
Bob

 

Thermostat or not?

No myth here! No thermostat, and you will run hotter than running say a 160.

You need something to keep the water in the engine long enough to pull the heat out of the engine. This is why the thermostat opens when it gets to temp, and flows back into the radiator to cool off. It doesn't have to be a thermostat, you can put a restrictor in place to control water flow. This is done on most race engines.

Regardless of how you do it, you want to control engine temp weather your computer controlled this will give you your best power, and life out of your engine.

 

......
...mis posted, sorry
..
.

 

yes, you do

 

Doc here, imp:

The thermostat REGULATES the water cooling..

It is not a matter of "Holding Back" the water circulation if you will, because it is a heat issue, not a timed issue..another words, 180 degrees is 180 degrees no matter how long it takes to achieve it..

You have 2 temps going for you, slightly hotter engine coolant, and the slightly cooler radiator water...the thermostat is what regulates the amount of cooling the coolant receives...Thermostat opens, the system stabilizes at a temp, then when below the cut off, closes and cools the water..

Without it, Cold Engines would run cold longer, (not good for it and parts that will wear, and unburned petroleum byproducts) and then Engine heat as it rises, would become additive...If you pull a long uphill grade, for instance, the heat would continue to build without regulation, until such time as pure airflow could bring the temp down..(which may be miles) which may be over 230 degrees by the time it starts back down..

Inversely proportional, If you run a long downhill grade the coolant may run as low as 125 degrees..not good for the engine at all...

The thermostat provides a short "Window" of cooling for the engine to keep it mostly constant..say 190 to 205 (ideal op temp) Which is why you don't see the gauge doing large excursions under different driving conditions...Also without this "regulation" a host of different things wouldn't work properly, like the radiator cap for instance, (constantly blowing off pressure/water)

The thermostat holds that "Window" of temp to keep the engine at optimum operating temps..The net results are better Fuel economy, lower emissions, better internal (oil) operating temps..

If the whole radiator runs hot during the high cycle, than that heat is transfered to the cooling side of the Transmission cooler..for automatics..meaning that fluid will also run hotter, cutting the useful life of the transmission..somewhere I read (may be true, may not..) For every hour the fluid runs hot, it cuts 10 hours life of the gearbox..

So yes a Thermostat is needed for a Better running engine..

Doc imp:

 

The thermostat regulates the RANGE of temp that your engine runs in by restricting the flow of cooland throught the sysytem. If your engine is too cold the thermostat (say a 160) will close and allow the temp to build up. When the tempurature rises to 161 degrees the thermostat will open and try to keep the tempurature at 160 degrees by allowing coolant to pass through the rad. Without a thermostat the size of the radiator becomes the main determinming factor in the temurature that your engine runs at. If it is a large enough rad your engine may never reach proper operating tempurature.
This is not good. Generally the cooler an engine runs the more wear it will experiance. I have heard that the rate of wear is somthing like 1000% of normal during the first few minutes of warmup.
The rad in your vehical is designed to keep your engine cool enough to not destroy your oil, or have a multitude of other problems which may occur in extreamly hot conditions which may be compounded by things like headers.
Sooo the odds are without that $15 thermostat that takes what 20 minutes to install? Your engine is going to run too cold, wear out prematurely, and burn a lot of oil.

Guys that race may get away without running a thermostat because they operate in a far narrower band of conditions than a street engine ( especially in northern climates) because they can tailor their cooling systems to their operating situation.

So can you run without one? Yes. Would I? Not a chance.

Scott

 

Most engines today are designed to run about 195 to 220, when you below that range running too cool gas mileage drops dramatically.

 

I suppose this question was asked by every auto manufacturer about 70 years ago. Its funny they all came up with the same answer.

 

I dont agree with the take the thermostat and coolant flows too fast to remove heat idea.
When the thermostat fails and is constantly open engine doesnt run too hot it runs to cold thats the same as taking thermstat out.

I think even wide open the thermostat is providing some restriction that creates a certain amount of pressure in block that is greater than the radiator cap which helps prevent steam pockets from forming.

I would always run a thermostat or at least a metered orifice like the circle track guys do.

 

I dont agree with the take the thermostat and coolant flows too fast to remove heat idea.
When the thermostat fails and is constantly open engine doesnt run too hot it runs to cold thats the same as taking thermstat out.

I think even wide open the thermostat is providing some restriction that creates a certain amount of pressure in block that is greater than the radiator cap which helps prevent steam pockets from forming.

I would always run a thermostat or at least a metered orifice like the circle track guys do.

You said it yourself, even an open thermostat will have some restriction. From past expierence running with no thermostat, or restrictors my engines have run hotter.

 

Ding ding ding. The winner is Greg!

Here is an post from another site that I have read in the past. I wish I could take credit for it but I'm not that smart. hahaha



What some people will say in public. This is absolutely false, of course. Try to conceive of blowing on something hot, say a spoonful of soup, first slowly and then more rapidly. Which cools faster? For extra credit, try imagining the same spoon with first slow and then fast water moving across the bottom. Sheesh!

The issue with running without a thermostat is two-fold. The first part is that the thermostat provides drag on the water flow. This drag increases the backpressure the water pump and all of the enginesees. This additional pressure, over and above the nominal 15 psistatic pressure the radiator cap sets, raises the boiling point of the coolant. The reason this is important is that it suppresses localized film boiling at hot spots such as around the exhaust port. The transition from nucleatic boiling (bubbles of steam originating from irregularities on the surface) to film boiling (where the hot surface is coated with a film of steam) is called Departure from Nucleatic Boiling or DNB. DNB is very bad, for steam is a very good insulator compared to water. Once DNB occurs, the area under the steam gets hotter because the steam doesn't remove very much heat, adjacent metal which is still wetted heats from conduction. DNB happens there. The process spreads until substantially all the coolant-wetted surfaces are insulated by a film of steam. The engine overheats. In addition, the buildup in steam pressure forces the radiator cap open, bleeding coolant, therefore making the situation worse.

The second issue is that of water pump cavitation and surge. If the pump is operated at high RPM with insufficient head pressure(provided by the frictional losses in the coolant passages and the thermostat), there is a great likelihood that the pump will either cavitate (localized boiling and/or degassing on the impeller) or surge (an unstable flow regime). Either phenomena is destructive. Cavitation's collapsing bubbles act like little sand blaster, eroding away impeller material. Surge can do the same thing and in addition, can vibration stress the impeller enough to break it. Many times what looks like corrosion damage to the impeller, especially when the housing is damage-free, is actually cavitation damage.

The myth of velocity originated among those unschooled in physics or thermodynamics, I suppose, because a common racer "solution" is to press a fixed restriction into the thermostat housing neck when no thermostat is desired. The conventional (but wrong) wisdom is that the restriction "slows the water" as stated by the previous poster. In reality, all it does is provide some more dynamic pressure in the block by restricting the flow. The exact same result could be accomplished (assuming the water pump doesn't surge or cavitate) with a higher static pressure (cap pressure), assuming the system could withstand it.

 

Maybe Fords are different but I have never noticed any difference in Temp with or without a thermistat.

Just to add in, my current 408w runs the same with/wo one, and I custom lathed my own water pump pulley which is about 1/2 the diameter the stock one should be, so technically im turning even faster then most V8's. My purpose was to save 250$ on an SVO pulley set and all I had was 3.5" diameter stock to start with. Anyhow point and case, If this theory was true my case would of shown more of a difference then other V8's.

Perhaps its more related to motor design and water passage design then it is to just try and answer it by YES or No

 

thermestats

Ding ding ding. The winner is Greg!

Here is an post from another site that I have read in the past. I wish I could take credit for it but I'm not that smart. hahaha



What some people will say in public. This is absolutely false, of course. Try to conceive of blowing on something hot, say a spoonful of soup, first slowly and then more rapidly. Which cools faster? For extra credit, try imagining the same spoon with first slow and then fast water moving across the bottom. Sheesh!

The issue with running without a thermostat is two-fold. The first part is that the thermostat provides drag on the water flow. This drag increases the backpressure the water pump and all of the enginesees. This additional pressure, over and above the nominal 15 psistatic pressure the radiator cap sets, raises the boiling point of the coolant. The reason this is important is that it suppresses localized film boiling at hot spots such as around the exhaust port. The transition from nucleatic boiling (bubbles of steam originating from irregularities on the surface) to film boiling (where the hot surface is coated with a film of steam) is called Departure from Nucleatic Boiling or DNB. DNB is very bad, for steam is a very good insulator compared to water. Once DNB occurs, the area under the steam gets hotter because the steam doesn't remove very much heat, adjacent metal which is still wetted heats from conduction. DNB happens there. The process spreads until substantially all the coolant-wetted surfaces are insulated by a film of steam. The engine overheats. In addition, the buildup in steam pressure forces the radiator cap open, bleeding coolant, therefore making the situation worse.

The second issue is that of water pump cavitation and surge. If the pump is operated at high RPM with insufficient head pressure(provided by the frictional losses in the coolant passages and the thermostat), there is a great likelihood that the pump will either cavitate (localized boiling and/or degassing on the impeller) or surge (an unstable flow regime). Either phenomena is destructive. Cavitation's collapsing bubbles act like little sand blaster, eroding away impeller material. Surge can do the same thing and in addition, can vibration stress the impeller enough to break it. Many times what looks like corrosion damage to the impeller, especially when the housing is damage-free, is actually cavitation damage.

The myth of velocity originated among those unschooled in physics or thermodynamics, I suppose, because a common racer "solution" is to press a fixed restriction into the thermostat housing neck when no thermostat is desired. The conventional (but wrong) wisdom is that the restriction "slows the water" as stated by the previous poster. In reality, all it does is provide some more dynamic pressure in the block by restricting the flow. The exact same result could be accomplished (assuming the water pump doesn't surge or cavitate) with a higher static pressure (cap pressure), assuming the system could withstand it.

well stated. i am amased at the miss info regarding cooling systems out ther.with no therm the by passis not functioning as desighned and in some systems this will cause over heat

 

http://www.stewartcomponents.com/tech_tips/Tech_Tips_3.htm

 

What about a nice high flow ball valve so you could restrict the flow?
I never liked the idea of a thermostat, but do like the restricter plate, but dont like taking my water neck off to change it.
Once you have it set where it works the best just take the handle off.

When I do run a thermostat I always drill some small holes in it to keep some water moving and avoid air in the system.

 

Well, I am heading to Detroit to let all of those nice young automotive engineers know that they, along with all other automotive engineers, that thermostats never were necessary. The boss(es) is going to mad as hell about all of the research and developement that went into such a worthless item and then to think of the cost for supplying the item, installing the item, and warrantying the item.

I believe that some folks initially forget that,

1). Automobile manufacturers never ever include anything anywhere that aint necessary. Do you suppose those engineers overlooked the possibilty of putting a disc in there and drilling a hole?

2). To randomly remove components of a complete, engineered cooling system is in and of itself ignoring that engineering.

 

thermostat problem

i love all these answers yes you need a thermo or a restrictor try to keep temp at 180/200 what ever it takes less than 160 no good more than 220 no good less radiator no fan what ever!!! 190 is nice.

 

You do need a thermostat to keep your engine at a minimum temp, and without one in the winter, you will freeze your a** off. I don't believe that your engine will run hotter without one. I think some of the overheating problems come from using a cooling system designed for 250 hp and trying to run 600 hp on the same cooling system. HP is energy, energy is heat. More hp and you need more cooling.
Bob

 

I will agree that all the things put on autos are there for a reason but sometimes that reason is void. such as a catalytic convertor, sure it helps with pollution but when you take it off you get a performance gain. same with smog controls. as for needing a thermostat for confort features like the heater, I dont need that cause I never drive it in the winter anyway. so I dont buy the because an engineer put it there it needs to be there.