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Old 10-20-2005, 11:27 AM
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Do you NEED a thermostat?

is it bad to run an engine without a thermostat? I dont use my heater so I dont need it for that. I didnt know if the water pump needs to have some sort of back pressure on it.
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Old 10-20-2005, 11:48 AM
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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.
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Old 10-20-2005, 12:07 PM
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Quote:
Originally Posted by DoubleVision
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
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Old 10-20-2005, 12:18 PM
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I was under the same impression as Bob C. and my engine is a 70 non computer controlled engine, so thats not an issue.
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Old 10-20-2005, 12:42 PM
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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.
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Old 10-20-2005, 01:17 PM
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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
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Old 10-20-2005, 01:55 PM
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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.
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Old 10-20-2005, 02:00 PM
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Quote:
Originally Posted by brainsboy
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
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Old 10-20-2005, 02:12 PM
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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.
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Old 10-20-2005, 02:57 PM
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......
...mis posted, sorry
..
.

Last edited by brainsboy; 10-20-2005 at 03:31 PM.
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Old 10-20-2005, 05:03 PM
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yes, you do
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Old 10-20-2005, 05:31 PM
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Doc here,

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
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Old 10-20-2005, 06:10 PM
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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
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Old 10-20-2005, 06:19 PM
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Most engines today are designed to run about 195 to 220, when you below that range running too cool gas mileage drops dramatically.
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Old 10-21-2005, 12:46 AM
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I suppose this question was asked by every auto manufacturer about 70 years ago. Its funny they all came up with the same answer.
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