Always. I want my engine to get up to its optimal running temp quickly, and stay there. I can definitely tell a difference before it's warmed up, and the thermostat keeps the temperature stabilized. Without it I might do 150 on the highway and 190 in traffic, and fluctuate back and forth a lot depending on speed. I can't see all that rapid expanding and contracting while I drive being a good thing. I also like to use my heater in the winter... But there have been times when it made sense to go without one. I had a POS slant-six Dodge truck that would blow oil at normal temp but run fine cold, so I left it out. And my dad's truck had a minor head gasket leak, so my brother put some of that miracle-head-gasket-in-a-can junk in there and took out the thermostat to reduce coolant pressure. But these are just temporary, "get you down the road until it can be fixed right" kind of situations.
I have been building only performance 302's and 351's for the last 15 years. I have yet to ever see one single motor overheat due to water running too fast through a radiator because of not running a thermostate. Water flow is going to be control more by the size and number of cores in the radiator than anything else. Ben
High Volume water pumps are generally used with larger than normal cooling systems. IE: Big tube aluminum radiators.They provide more coolant flow yes.But,they do so becuase the heat exchanger (radiator)has more surface area(larger tubes)to allow it to transfer more heat to the tubes/fins and air flow from a larger amount of coolant at one time.Thus the water pump flows more coolant to be able to utilise the bigger rads capacity.Make sense??? The radiator (heat exchanger) will not do its job well if the hot coolant does not remain in it long enough to transfer its heat to the core tubes/fins. Hence one reason for the T stat. IE: Coolant absorbes heat from the engines combustion process and friction(Note: oil is also a coolant)It heats to the point where it opens the T stat at a level determined by the T stats heat threshold be it 160 or 195 deg.At this point, cold coolant in the radiator that has been cooled by heat transfer enters the engine,cooling it and closing the T stat when it reaches it,causing it to close.The hot coolant in the rad now begins its process of heat exchanging and cools down.The coolant in the engine heats to the point where it opens the T stat and starts the process all over again. Pressure in the cooling system is created by the water pump circulating coolant in a closed system AND the heat produced by the engine causing expansion of the coolant(hence the need for an overflow tank) The caps pressure rating simply sets boiling point and when the coolant stops expanding.If the coolant were allowed to continue expanding as it builds heat and pressure it would simply find another way out of the engine (through the weakest point).Back to the overflow tank... The cap releases pressure at its set point allowing pressure to release and dribbling coolant into the overflow tank.This will also create a negative pressure environment which allowes coolant back into the radiator from the coolant tank depending on the tanks setup.Some just catch...most catch and return coolant to the system. I can go on if you wish but I am hungry and must eat dinner now or the blurry vision will make my spelling and grammar worse than it is allready.
ummmm, just want to point out also that coolant is not water. water has one boiling temp and purpouse in a radiator. Coolant however has SEVERAL..... the ethylene glycol keeps the water from dropping below freezing helping to stabalize the temp and work with the heat transfer properties of the water to absorb that heat out of the engine. the inhibitors and lubricants are self explanatory. the one most often overlooked and the part that is usually lost first in coolant making it lose its max cooling capability, is what is most often overlooked\unknown. Methylene Chloride is in coolant in one of the smallest percentages but is a chlorinated solvent related to freon. it helps the radiator act like the cooling coils in your refrigerator, increasing the heat flash capabilities of the system. that is why a good cooling system needs to have a pressurized cap. you cannot flow water too quickly through the system, however as your flow rate goes up the ability of the MCH to cool and return goes down. there is much more than the coolant of course to the comparison of when the cooling systems performance has been exceeded and the heat will not be maintained, however i think that may help to clarify why there is a window of flow rate vs cooling capability or make it muddier? dont get me wrong, i run a high flow pump since i spend a lot of time at low idle but i would never run unrestricted with no t-stat either. as for temp, i have to worry about winters where even with the t-stat i barely get it open and summers where electrics barely keep up in town....
The MCH raises the vaporization point(latent heat of vaporization threshold) Keeping the coolant in the system as opposed to it cooking off...Very good points you raise sierra grabber...
See, I told you all this would end up being a neat thread! Very informative. Lots of stuff here I have never heard of. Keep it up guys
Thats the argument/reasonability that I've come across, to low a t-stat makes it where the coolant doesn't stay in the radiator long enough to cool down... so I guess I'll be changing that my t-stat soon. I'm in arizona so I get highs of 110 degrees, so in stop and go my car gets upto 230+ although in winter it stays between 160 and 170 which is as I said before abit low. Now I got to remember everything I need to do it... I know it's basic but life has prevented me from doing any work on my care for a very long time. t-stat, gasket, gasket sealer... try to remember the torque specs for those bolts... thanks for the comments.
If you dont need to...dont...If you do need to... figure out why and fix it.Sealer isnt recommended because, ham fisted fellows will use too much and get it into the cooling system and or, plug up the T stat.You can use it...in moderation.Should be a thin film between the housing and gasket if at all.JMO
Leeches are still used today for post-op body part reattachment. Their saliva prevents clotting and keeps the blood flowing for healthy healing. Actually I don't know much about leeches or cooling problems for that matter. But I have a book on the subject (cooling, not leeches). I also work with chillers, heat exchangers, and pumps in a high rise office building, so the subject is interesting and a lot of intelligent and thought provoking comments have been made. First the basics: Retarded timing, lean fuel mixture, vacuum leaks all contribute to overheating. Shroud is a must, and an over-sized transmission cooler installed in series, but before the radiator will reduce heat load. Make sure you have a recovery system. T-stat installed in correct direction. Synthetic engine oil/ automatic trans fluid should help too. T-stat: expect to see 15-20deg above rating on a hot day. Even higher if you are pushing the engine. But I would have to agree, a 160 and a 180 will flow the same at 180 degrees. Now according to what I have read on the subject engines can overheat due to circulating too fast OR too slow. You need to find the correct rate. the best way to do this is by running a test: establish a baseline. Then remove the t-stat, if it runs cooler, you need to increase the flow. I would try a high flow t-stat, then add the high volume water pump if needed. The high flow t-stats respond quicker and have a larger passage but still close to allow proper warm up. If overheating is worse without a t-stat, you are flowing too fast. Although thats not likely, a pulley ratio change would be in order. Now something to think about: "Water traveling too fast through the radiator to cool" sounds reasonable enough to me. However the larger the radiators capacity, the slower it will flow, for increased cooling.
Hmm, I am gonna have to dispute this. While antifreeze raises the boiling temp, which allows cooling to continue where water will boil and lose its heat carrying efficiency, pure water does conduct heat better than a water/antifreeze mix. Without getting too technical, refrigeration by nature is a cycle of refrigerant going from a high pressure to a low pressure through a metering device where there is flashing and boiling through the evaporator. The flashing and boiling (evaporating) removes BTU's by reducing latent heat between changes of state (liquid to gas). There isnt a significant pressure drop nor boiling or flashing and condensing of refrigerant going on inside a radiator. While antifreeze is needed for water pump lube, freeze protection and raising the boiling point, cutting the ratio will actually increase cooling. The pressurized cap is important simply because the increased pressure suppresses coolant boiling by raising the boiling point (weather pure water or a coolant mix). There are also additives such as "Water Wetter" or "Purple Ice" that can be added to coolant for increased heat transfer although I dont have any experience to confirm that.
I have the griffin universal radiator from summit, edelbrock victor aluminum water pump, external trans cooler, and 7qt oil pan and 160 t stat thats about to get changed to a 180 for gas mileage. at 160 ive noticed a huge difference in my gas mileage going down. but anyway, my car never gets over 160 anywhere, except hotlapping and staging at the dragstrip and then it bumps to about 190 as i am not running an electric fan.
That stuff does work. You've brought up interesting things and I agree with most of it. Even further explained how running without a thermostat can decrease cooling efficiency under the right conditions. This is a great thread. My original point can be condensed simply into this... "Not letting the water stay in the radiator long enough to allow heat transfer" is the concept I disagree with, and consider a widely-believed myth. Any one of the other numerous reasons mentioned here why you should always run a thermostat, I agree with. I never suggest removing the thermostat except when diagnosing, or when trying to limp a car down the road until a problem can be fixed. I also think there's no point in running a thermostat rated far from a temperature you can maintain. The thermostat is just for setting the lower boundary of your running temperature. It doesn't hurt anything if you put a 160 thermostat in a car that wants to run 180, but if you use a 180 instead, you'll have a much narrower range of fluctuation during your daily romp around town. And I'm not an engineer, but I speculate that keeping the temperature relatively constant contributes to the longevity of an engine.
