[FNFGTO]

Can I get some opinions on not running a thermostat on a 69 GTO 400. No heating problems but would like to get opinions on the pros & cons.
Thanks, John

[jwcfbd]

from what I have heard it's a bad idea. The coolant doesn't spend enough time in the rad. if you remove the thermostat. It will run hotter without it.

[kate`s67gto]

Use a stat it helps keep the engine at a constant temp. Better for warm up =better fuel economy , in this day you want all the MPG you can get.

[rareta]

Yes you do need to run a stat or one at least with the guts removed. You need a restriction to slow the coolant down so it can pick up the heat from the motor.

[Red Box Rebel]

1. Definetly need a stat. It is there to maintain an operating temperature. You can change the heat range of a stat, but you still need one.

[Pontirag]

A mear restriction is not enough. you need pressure to hold the water in a fluid form against all contact surfaces in your engine. Otherwise you may get localised boiling at a hot spot where the water boils away from the surface which is hotter than the surfaces around it. If the water fails to cool that area sufficiently or not at all it may eventually ... or suddenly cause damage like blown gaskets or cracks to develope.

What problem or situaltion are you trying to correct/ improve. Fixing a problem ,per se is not normally achieved by disabling another piece of equipment like a thermostat. Unless its stuck in the closed position and your broken down along the highway. Other wise, with the emphasis on wise, keep it in and troubleshoot other components or conditions that effect the system.

Thermostats have been around almost as long as the watercooled combustion engine itself.You find them in just about every water cooled engine made. there is a reason, other wise why would manufacturers impose cost, reliability and warrenty issues upon them selves. Furthermore, engineers have attempted to redesign or invent countless different types of thermostats. While the design may vary over time, its purpose has never changed. That in and of itself is a pretty clear indication of the need to thermostaticaly control water temp.

[BILL BOWMAN1]

I'm the odd man out, all of my vehicles run cooler without a thermostat. I'm not saying anyone is right or wrong, just my cars run cooler without one, but have to put them back in wintertime to make any heat.

[LPete]

I think one of the most important reasons for having a thermostat is to help rid the oil of contaminants -- if the engine doesn't heat up the oil will become loaded with unburned fuel and water, causing acids and sludge to build up and eventually damage the engine.

[george kujanski]

The idea of "moving the coolant thru the radiator too fast" is a fallacy. More flow is better as testified by Bill Bowman. See......

http://www.stewartcomponents.com/tec...ech_Tips_3.htm

The thermostat helps maintain a minimum engine temp and a high flow stat allows more flow for best cooling. Period.

[70GS455]

Get a high-flow thermostat, like the one from Stewart.

[george kujanski]

Think of it this way: The laws of physics and heat transfer don't change abruptly at some tstat opening. Try an example:

Assume you start with no restriction, large pipes and hoses... and assume the engine gets hot. Now start adding restrictions and the engine supposedly gets cooler...keep restricting to the point where you end up with a pinhole...is the engine going to be the coolest at this point, or will it be the hottest? A gut feel tells you it will be the hottest.

Sorry gang, the real world doesn't work like that; it wouldn't get cooler as you restricted it than all of a sudden get hotter.

In the real world due to the laws of physics and heat transfer, the results trend in one direction and then usually flatten out, ending up with little or no further improvement/degradation due to restrictor size.

Now say you start with a system with no stat. The engine is producing waste heat ( a certain amount of heat per unit time) less than the capacity of the cooling system. The engine temp will be low since the cooling system can dump more heat than the engine is making.

The cooling system also can move a certain amount of heat per unit time depending on air flow rates, coolant flow rate, size of radiator, etc.

Now increase the power output of the engine; the amount of waste heat will increase also, (more heat per unit time). The cooling system must move this heat from the engine to the rad to keep the engine cool. Since more heat is generated per unit time, the heat must be removed faster also.

The ability of the system to dump heat is affected by the airflow thru it, the coolant flow thru it, and the heat exchanger size.

Since the radiator size is fixed, in order to move the heat faster, we need to move more air and more coolant per unit time.

I hope this helped and not confused.....

George

[DScruggs]

Running without a T-stat CAN NOT and WILL not make any car run hotter ever. You can tell me all of your anecdotal who shot John stories until the cows come home and it still is a dog that wont hunt. A T-stat also hes ABSOLUTELY ZERO effect on pressure at any point on the systems EXCEPT as a function of temperature.

That said running without a T-stat is not wise due to the fact that engines are designed to run at certain temps. A way too cold engine will not be operating within design parameters.

[Matt Danger]

Let me just add that when I got my car it had no thermostat and took a good 5 minutes to warm up and run properly. It drove me nuts and I was like "Man I need a carb rebuild or something to take care of this" but then I replaced the thermostat and sure enough the car fired and ran great right from cold.

The thermostat helps control the temp of the block and when the engine is cold you do not want coolant circulating or else it'll take a long time to warm up, like in my case.

And, basically there's no point to take it out. You gain nothing.

[David Holmberg]

For a street driven car you are correct, a thermostat is vital to keeping the temps in the motor in the desired range. Heat is horsepower, but it also brings along its friends detonation, vapor lock and heat soak.

There is a time and place for running without a thermostat, and that would be a track car where you want to be able to circulate the water at any temp, at any time. This way you can cool the car down as quickly as possible, to be ready for the next round, or lap.

[engineer]

put a pressure gauge on the top radiator hose or replace the cap on a downflow radiator with a gauge and you will see what the pressure difference is with or without a t stat. The pump is centrifugal and always will run better with a pressure restriction on the outlet, ie the t stat. it is that pressure drop thru the radiator and t stat that keeps the pump fluid from bubbling (vaporizing) inside the block passages when there is a hot combustion area. like Pontirag said. although you tend to think of the heat release being uniform throughout the block, actually it is not, but big heat releases are individually happening only around the cylinders being fired. The pump flows fluid thru block passages based on pressure through the path of least restriction, the least pressure drop, the more flow. plugged passages, less flow, have higher pressure drop. no surprise, but by the time it reaches the water outlet, the t stat will provide the final restriction to keep water passages thru the heads flowing, if not , the water flow will not uniformly pass thru all passages and therefore not remove all the heat it can. Yes it looks like the water temp might be cooler without t stat, but unless you looked at all temps at various points on the block, you do not know. The engineers did that work at the factory and do know the value of the t stat. it is true you can not flow too much thru a radiator because the tube size will limit the flow regardless of how much you try to push thru any individual tube. but you can change the water pump characteristics by varying outlet pressure and the t stat at certain conditions gives a known pressure drop. A t stat is an orifice plate which is a device to affect pressure, it is higher upstream of one. It will only affect a change when the upstream flow reaches a certain point of heat (temp) and flow. Even race cars have an orifice plate in the water loop and there the attempt is too keep engine efficiency high which is a controlled heat release. most horsepower for the amount of heat produced. if it was better without, don't you think they would leave them out? there is no magic temp. to achieve. too cool is too bad for combustion products in the oil but too high is only bad if the system can not handle the higher pressures as set by the radiator cap. Mercedes use a 30 psig cap. the system can handle the pressure and the fluid boiling point is greater. (less tendency to vaporize). Does that mean the car needs to runs a 180 deg F? It can run at hotter temps and the engine will still be efficient. Look at new cars today, with smaller radiators, and running hotter temps. are they less efficient? no quite the opposite, they are designed to perform at hotter water temps and work better. Can we do that in our vintage cars, somewhat but we are limited by the stock engine water passages, metallurgy, the stock water pump in the timing cover, etc. unless you change enough of these and lose that stock look.

[BILL BOWMAN1]

Originally Posted by george kujanski

The idea of "moving the coolant thru the radiator too fast" is a fallacy. More flow is better as testified by Bill Bowman. See......

http://www.stewartcomponents.com/tec...ech_Tips_3.htm

The thermostat helps maintain a minimum engine temp and a high flow stat allows more flow for best cooling. Period.

Thanks George, I always believed that to be true.

[Geoff]

Ditto.

[hal101]

the only purpose of a thermostat is to provide a minium operating temp

[engineer]

sorry, it is also a pressure device for the pump

[billkinney]

If you dont use a tstat You will over heat everytime you get stuck in traffic on the hot days. The radiator will not keep up with engine and tranny heat at an idle if it doesn't stop the water in the radiator to cool off. Maybe you can get away with it in the far north but one day you'll get nailed. Been there done that...oops
Bill