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I tried a search but it really only brings up threads about overheating. I know the previous owner of my car (98 Z28 in sig) put a cooler thermostat in the car but I'm not sure how cool that stat is. The car rarely ever gets barely over the first temperature hash mark and never reaches the normal operating temperature my old 99 SS ran at (170-180 degrees). I'd say on average the car is running anywhere from 120 -130 degrees. The fans are also often on and continue to run once the car is cut off. Is there any issue with this?
The car has never overheated on me the entire 8 months or so I've owned it save for last weekend which was my fault. I was driving around some mountain roads about 15 to 20 mph higher than the suggested road signs for a good 45 minutes or so all up hill when I noticed the car was starting to run where my old SS used to run. Then it kept getting hotter. And hotter. I pulled over and come to find out my dumb *** did not tighten the radiator cap all of the way which allowed most of the coolant to boil out of my car. After topping the car off with water, it has been fine since.
If its too low of a t-stat....like a 160*F t-stat....you could get to a point where it never closes fully.....which is what you want. If it does not close fully than the hot coolant that flows into the radiator when the t-stat opens will continue to flow through the partially open t-stat. This causes a downward spiral....
The coolant MUST stop moving through the system. If it is allowed to continually flow through a partially open t-stat then gradually your coolant will never begin to cool...it will gradually continue to get hotter and hotter. Then it will reach a point where the t-stat will stay pretty much open all the time....Then...its over. You will overheat.
I had a 160*F in my 427ci back in 2002 when it was THE THING TO DO. Its not the best choice. I changed to a 180*F t-stat and I ran cooler under all conditions. WHY.....because the t-stat would close fully, stopping the flow completely, and allowing the HOT coolant in the radiator more time to sit and cool off before re-entering the engine block/heads.
180*F...IMO...is the best for any LSx engine. I put that same 180*F into my new IRON BLOCK 390ci....it runs very cool.
185-190 or so.....On a hot *** South Florida day in stop and go traffic....210*F with the A/C on. But as soon I start moving it will drop down to 190 or so......
On the highway it sits around 180-185.......A/C on...hot *** day.
Thermostats are designed to stop the water, so that it will heat up quickly inside the engine, to warm the engine up faster. Driving an engine (any engine) with cold coolant is associated with premature wear and tear.
You need the coolant to hit 180*F+ asap, optimum ranges from 181-225*F.
The next is oil, you must also warm the oil up to 160-180*F before doing any hard driving. Running an engine hard with cold oil is also associated with premature engine wear.
If you remove the T-stat, the coolant might never warm up. It depends on the cooling system capacity, ambient temp, and other factors.
For your situation, I think you should look at it this way:
There is no such thing as a "free lunch." The lower temperature thermostats are on the market for a reason and the higher temps are on our cars for a reason.
When you change the average temperature of the engine, you change the conditions in which chemistry occurs in the combustion chamber. This will have an impact on emissions, fuel mileage, and possibly driveability.
That being said, if you modify the engine to the point where you need to look at that internal combustion/chemistry or are using the car for a non-standard use (pulling a camper, trailer, etc.) then it might be something you should look at.
Your stock engine should be able to go up and down desert mountains all day long if properly maintained.
SO it sounds like I'm going back to a stock thermostat. I believe the car might also have an edited fan profile but that I am fine with.
When I switched from a 160 to a 180....I left the fan tuning in the PCM for the 160.
My engine temps are great.
Just think, if the 180 t-stat can't quite keep up with cooling, then the fans will come on before things get too hot. This way you stop the momentum of heating up from getting out of control where the t-stat will not fully close any more.
As soon as the t-stat is not allowed to close fully, you are on your way to overheating, or running hot. The only way to fix that situation is to drive at a steady cruising speed on the highway. City driving on a hot day, if the t-stat cannot close all the way....and you are doomed....Or you will run hot on the ragged edge.
The coolant MUST stop moving through the system. If it is allowed to continually flow through a partially open t-stat then gradually your coolant will never begin to cool...it will gradually continue to get hotter and hotter. Then it will reach a point where the t-stat will stay pretty much open all the time....Then...its over. You will overheat.
I read this as nonsense. Did you mean to type this in this way? At a fundamental level, to say that fluid must completely stop moving through the radiator - the very place where the heat is actually removed - in order for cooling to happen doesn't pass the common sense test.
If you are saying that the coolant's effectiveness is directly related to the speed that it flows through the engine, that is not correct either.
Originally Posted by LS6427
Just think, if the 180 t-stat can't quite keep up with cooling, then the fans will come on before things get too hot.
The thermostat doesn't have a cooling function. The radiator does that part. The thermostat just holds heat back in the engine - to a certain point, then it opens up for the rest of the system to do its thing.
^ This is easier to put in to perspective when one remembers that "cooling" is technically the removal/release of heat.
If its too low of a t-stat....like a 160*F t-stat....you could get to a point where it never closes fully.....which is what you want. If it does not close fully than the hot coolant that flows into the radiator when the t-stat opens will continue to flow through the partially open t-stat. This causes a downward spiral....
The coolant MUST stop moving through the system. If it is allowed to continually flow through a partially open t-stat then gradually your coolant will never begin to cool...it will gradually continue to get hotter and hotter. Then it will reach a point where the t-stat will stay pretty much open all the time....Then...its over. You will overheat.
I had a 160*F in my 427ci back in 2002 when it was THE THING TO DO. Its not the best choice. I changed to a 180*F t-stat and I ran cooler under all conditions. WHY.....because the t-stat would close fully, stopping the flow completely, and allowing the HOT coolant in the radiator more time to sit and cool off before re-entering the engine block/heads.
180*F...IMO...is the best for any LSx engine. I put that same 180*F into my new IRON BLOCK 390ci....it runs very cool.
185-190 or so.....On a hot *** South Florida day in stop and go traffic....210*F with the A/C on. But as soon I start moving it will drop down to 190 or so......
On the highway it sits around 180-185.......A/C on...hot *** day.
.
See, I experienced the total opposite when I was doing my coolant flush and had completely removed the thermostat from the system, it was only after a LONG (over an hour) highway drive that I was able to get it up to full operating after slowing down and getting caught at a red light.
OP, the problem is you don't want things to run that cool, the engines are designed to operate at certain temperatures, being to cold leads to other issues, some of which include little to NO HEAT coming from the heater in the winter/colder months, also until you get to operating temp you run in "open loop" (if i'm remembering the right terminology) which dumps more fuel into the motor leading to bad fuel mileage really bad emissions as lots of unburnt fuel goes out the exhaust which is also bad for the CATs (if you have those)
I read this as nonsense. Did you mean to type this in this way? At a fundamental level, to say that fluid must completely stop moving through the radiator - the very place where the heat is actually removed - in order for cooling to happen doesn't pass the common sense test.
If you are saying that the coolant's effectiveness is directly related to the speed that it flows through the engine, that is not correct either.
The thermostat doesn't have a cooling function. The radiator does that part. The thermostat just holds heat back in the engine - to a certain point, then it opens up for the rest of the system to do its thing.
^ This is easier to put in to perspective when one remembers that "cooling" is technically the removal/release of heat.
In order for the coolant to have enough heat removed BEFORE it goes back into the block/heads, the t-stat must close to stop the flow of coolant through the system. Then as the cooler "coolant that just flowed into the block/heads starts to heat up, the t-stat will slowly open. swapping once again, the HOT and COOLER coolant.....and so on.
What dooms an engine.....is when things get too hot and even after the t-stat opens to swap the HOT and COOLER coolant.....the t-stat does not FULLY close. ((this can be seen if you idle an engine long enough with the A/C on and the radiator cap off. It will keep getting hotter and hotter.....and at some point after the flowing coolant does a swap.....the flow will still remain. It will be slight, but if you see the flow never stop completely, thats when overheating is coming.
When my t-stat opens and flow begins (radiator cap off) and then the swap has occurred, and the t-stat is now sensing cooler coolant....it closes completely.....because my coolant flow 100% stops. Then as you watch it.....you will see it start to trickle..(t-stat is cracking slightly open)...then spit..(its opening more)...then start to flow (t-stat is fully open). Then that flow will stop 100%....(t-stat just closed).
If someone has an issue that causes them to overheat....in all cases....the t-stat reaches a point where it never closes fully and coolant continually flows....and heats up more and more and more....then its over...OVERHEAT IS NEXT.
Basically....remove the t-stat and go sit in stop and go traffic on a hot day....you will overheat in a hurry.
And a tstat's purpose IS NOT to allow an engine to warm up when its cold..LOL...thats just what occurs because its not going to open until the coolant in the heads reaches a certain temp to command the t-stat to open. Its designed purpose is to regulate the temp as close to a certain temp as it can.
But a t-stat is like a red headed step child....it can be abused. When you abuse a tstat and try to overwork it.......it will NOT fully close and you will start the viscous cycle and you will be on your way to overheating.
Go drive a factory sized cooling system at 140mph for more than 4 minutes straight.....you will start to overheat. Because the tstat cannot keep up with how much coolant needs to be cooled in a given time.
I've driven a Lambo Merc out on Alligator Alley for about 5 minutes at 175mph....temps started rising past normal and wasn't gonna stop. We slowed down and it cooled off.
My car...with my 427ci....did well over 200 top end runs in its life. Many were held at 160mph for 3-4 minutes straight......it would always start to get hot. Slowing down is the only remedy.
Basically....remove the t-stat and go sit in stop and go traffic on a hot day....you will overheat in a hurry.
There are a lot of internet rumors about this with a lot of bad/false information attached to them.
No matter what tidbits we want to attach to, the laws of thermodynamics can not be altered:
- Heat is generated in the engine by friction.
- Heat is transferred to the coolant in the engine.
- Heat is released to the air at the radiator, making the coolant "cooler."
- The rate of heat transfer in the engine or the radiator depends on the temperature difference between the coolant and the device, the properties of the two materials, and the time the two are in contact. (There is no thermodynamic reason that says coolant needs to stop for efficient heat transfer to occur.)
At operating temperature, let's say 180*, then the thermostat is full-open. (just like it would be if it were removed) A properly designed system is meant to operate in this way:
Could removing a thermostat cause an engine to overheat? Maybe. But - only if the coolant is not spending enough time in the radiator for the heat to be removed from the system. If the system can't handle the extra flow from removing the little bit of restriction of a removed fully open thermostat or if an aftermarket change was made, (bigger water pump) these things could be problematic.
A stock car, with a fully open thermostat, operating in normal situations, should not overheat. Car manufacturers take their new models and flog them in the desert for months to prove this particular point out before they even hit the market.
Originally Posted by LS6427
In order for the coolant to have enough heat removed BEFORE it goes back into the block/heads, the t-stat must close to stop the flow of coolant through the system. Then as the cooler "coolant that just flowed into the block/heads starts to heat up, the t-stat will slowly open. swapping once again, the HOT and COOLER coolant.....and so on.
What dooms an engine.....is when things get too hot and even after the t-stat opens to swap the HOT and COOLER coolant.....the t-stat does not FULLY close. ((this can be seen if you idle an engine long enough with the A/C on and the radiator cap off. It will keep getting hotter and hotter.....and at some point after the flowing coolant does a swap.....the flow will still remain. It will be slight, but if you see the flow never stop completely, thats when overheating is coming.
^ So, this is not correct. This example neglects the fact that our cooling systems are pressurized. Once the radiator cap is taken off, the system will depressurize, and the fluid will not flow properly through the engine or radiator. This will impact the time part of the heat transfer equation and over heating can occur.
The thermostat doesn't make the system a start/stop proposition. Once the engine hits a temperature equilibrium, the temperature of the coolant going in to the engine will be cold, but it will gradually heat up as it travels through all the cooling passages and will be at a constant temperature as it exits the engine at the thermostat. That constant exit temperature will be the opening temperature of the thermostat, or greater.
Originally Posted by LS6427
And a tstat's purpose IS NOT to allow an engine to warm up when its cold
That IS one of the purposes. Here's a good external resource that details how a thermostat and this stuff works. If any of this is incorrect, I would like to see other external resources providing additional information:
There are a lot of internet rumors about this with a lot of bad/false information attached to them.
No matter what tidbits we want to attach to, the laws of thermodynamics can not be altered:
- Heat is generated in the engine by friction.
- Heat is transferred to the coolant in the engine.
- Heat is released to the air at the radiator, making the coolant "cooler."
- The rate of heat transfer in the engine or the radiator depends on the temperature difference between the coolant and the device, the properties of the two materials, and the time the two are in contact. (There is no thermodynamic reason that says coolant needs to stop for efficient heat transfer to occur.)
At operating temperature, let's say 180*, then the thermostat is full-open. (just like it would be if it were removed) A properly designed system is meant to operate in this way:
Could removing a thermostat cause an engine to overheat? Maybe. But - only if the coolant is not spending enough time in the radiator for the heat to be removed from the system. If the system can't handle the extra flow from removing the little bit of restriction of a removed fully open thermostat or if an aftermarket change was made, (bigger water pump) these things could be problematic.
A stock car, with a fully open thermostat, operating in normal situations, should not overheat. Car manufacturers take their new models and flog them in the desert for months to prove this particular point out before they even hit the market.
^ So, this is not correct. This example neglects the fact that our cooling systems are pressurized. Once the radiator cap is taken off, the system will depressurize, and the fluid will not flow properly through the engine or radiator. This will impact the time part of the heat transfer equation and over heating can occur.
The thermostat doesn't make the system a start/stop proposition. Once the engine hits a temperature equilibrium, the temperature of the coolant going in to the engine will be cold, but it will gradually heat up as it travels through all the cooling passages and will be at a constant temperature as it exits the engine at the thermostat. That constant exit temperature will be the opening temperature of the thermostat, or greater.
That IS one of the purposes. Here's a good external resource that details how a thermostat and this stuff works. If any of this is incorrect, I would like to see other external resources providing additional information:
There's not a single car that GM has ever built that can handle stop and go traffic like conditions in a 110*F desert, especially with the A/C on. Every one of them will over heat. Especially a Corvette. They sit at 225*F normally as is. They don't need a whole lot to push them over the edge.
Thats why every Corvette, Camaro, Trans Am and Mustang over here in Dubai....MUST have a larger radiator installed in them......because they will die in the summer on a normal 118*F day in traffic. When you see 20 cars pulled over on the highways or city streets in the summer....its because they are overheated and waiting for them to cool down.
Shops in Dubai take cars over here and they upgrade the cooling systems, on almost every make/model. They also have special tires for running long distances on hot days so the tires don't over-pressurize from the 160*F heat from the pavement.
Anyway....the only reason any engine, in any car, overheats....is because the tstat is slowly...gradually being overcome by hotter and hotter temps. Then it will reach a point where it will remain full open and then its all over....needle goes into the red.
I agree, that with the system properly pressurized, which allows higher temps before it boils over, a tstat on a normal driving day may not close "fully" each cycle that it opens and closes, but it sure does not always stay "fully" open for a long period of time. That will not allow any cooling time in the radiator, the coolant will never stop moving through the big giant metal heater.....the engine block/heads....and you will overheat.
Tons of people here have reported they had tstats that were stuck open....their symptom....Overheating. With a fully "stuck" open tstat the coolant will NEVER get enough sitting time in the radiator to cool off, it will re-enter the engine already hot, thats when the end is near.
If running with a fully opened tstat was no problem and would never cause an engine to overheat....everyone would delete them because its just another part that fails and then causes us to overheat, whether its stuck closed or stuck open, its an overheat situation.
And when I do my flushes and I start my engine with the radiator cap OFF...tstat removed.....the coolant gets hot in about 3-4 minutes while its free flowing non-stop through the system. So we do not need a tstat so we can warm our engines up in the winter...they warm up fast. The coolant surrounding the heads/cylinders are plenty hot. Try it....3-4 minutes and you will not be able to keep your finger in the radiator coolant.
Everything this guy says is incorrect, incomplete, conjecture. Just ignore.
LOOK at a T-stat. Its got a hole. Its not a very complicated part. The hole shuts to hold water inside the engine. The only result of this is: Engine is allowed to warm up. Once the engine warms up X*, the hole opens. Walaa, now the radiator can do it's job. If the radiator does it's job too well, the hole shuts again when the water temp drops below X*, once again holding water in the engine so it can warm up. Rinse and repeat. Doesn't take science or school to understand a hole opening / shutting.
Not to quote the entire post but mine handles daily driving desert heat. As does my suburban. And my daughters camaro. And my daughters S10. And my daughters trailblazer. Yes I have lots of teenage girls.
5 for 5 here.
My car and the S10 are heavily modded. Suburban is cam only. Camaro and TB are stock
A stock car, with a fully open thermostat, operating in normal situations, should not overheat.
Originally Posted by LS6427
Thats why every Corvette, Camaro, Trans Am and Mustang over here in Dubai....
Dubai ≠ "normal situations"
I'm sure AZ and Death Valley are not accurate approximations of the Gulf States. I'm also sure that drawing a correlation between conditions in Dubai and Florida is ludicrous.
With all due respect to my friends in the UAE, stock vehicles there will need modifications. Same goes for my friends living north of the Arctic Circle, those stationed in Antarctica, and anyone living above 13,000 feet.
I don't think the OP's situation is applicable to these situations. ^
OP, the problem is you don't want things to run that cool, the engines are designed to operate at certain temperatures, being to cold leads to other issues, some of which include little to NO HEAT coming from the heater in the winter/colder months, also until you get to operating temp you run in "open loop" (if i'm remembering the right terminology) which dumps more fuel into the motor leading to bad fuel mileage really bad emissions as lots of unburnt fuel goes out the exhaust which is also bad for the CATs (if you have those)
It will also lead to diluted/contaminated oil, as the open loop dumps fuel and causes cylinder wall wash down (with all of the problems associated with this as well) past the rings (YES, even very 'tight' rings).
Some will say that the first long highway drive will 'burn off' this fuel in the oil, but, IF it is bad enough, or the rings are just a little bit worn, even the extended heating of the oil will not get rid of it completely.
There's not a single car that GM has ever built that can handle stop and go traffic like conditions in a 110*F desert, especially with the A/C on. Every one of them will over heat. Especially a Corvette. They sit at 225*F normally as is. They don't need a whole lot to push them over the edge.
Thats why every Corvette, Camaro, Trans Am and Mustang over here in Dubai....MUST have a larger radiator installed in them......because they will die in the summer on a normal 118*F day in traffic. When you see 20 cars pulled over on the highways or city streets in the summer....its because they are overheated and waiting for them to cool down.
Shops in Dubai take cars over here and they upgrade the cooling systems, on almost every make/model. They also have special tires for running long distances on hot days so the tires don't over-pressurize from the 160*F heat from the pavement.
Anyway....the only reason any engine, in any car, overheats....is because the tstat is slowly...gradually being overcome by hotter and hotter temps. Then it will reach a point where it will remain full open and then its all over....needle goes into the red.
I agree, that with the system properly pressurized, which allows higher temps before it boils over, a tstat on a normal driving day may not close "fully" each cycle that it opens and closes, but it sure does not always stay "fully" open for a long period of time. That will not allow any cooling time in the radiator, the coolant will never stop moving through the big giant metal heater.....the engine block/heads....and you will overheat.
Tons of people here have reported they had tstats that were stuck open....their symptom....Overheating. With a fully "stuck" open tstat the coolant will NEVER get enough sitting time in the radiator to cool off, it will re-enter the engine already hot, thats when the end is near.
If running with a fully opened tstat was no problem and would never cause an engine to overheat....everyone would delete them because its just another part that fails and then causes us to overheat, whether its stuck closed or stuck open, its an overheat situation.
And when I do my flushes and I start my engine with the radiator cap OFF...tstat removed.....the coolant gets hot in about 3-4 minutes while its free flowing non-stop through the system. So we do not need a tstat so we can warm our engines up in the winter...they warm up fast. The coolant surrounding the heads/cylinders are plenty hot. Try it....3-4 minutes and you will not be able to keep your finger in the radiator coolant.
.
and the way you "beef up" a cooling system to handle larger heat loads from extreme temperatures is you install BIGGER RADIATORS, since it's the RADIATOR that serves the function of removing the heat, once you get over the temp on the themostat, thats it the thermostat is OPEN AND STAYS OPEN unless the cooling system is powerful enough (large radiator and fan controller providing more cooling then stock) to lower operating temps back low enough for the thermostat to close and in a situation with a stock car in 118* heat of the desert that thermostat will never close and it's because the cooling system is being pushed beyond it's capacity to cool which leads to overheating, the overheating is not caused by the thermostat staying open its caused by the radiator and fans being to small (rad) or not enough airflow (fans), lets give an example, the thermostat in my Trailblazer is like a 190* (which is the point at which the thermostat is fully open), once my TB reaches operating temp it fluctuates between 207 to 217 depending on airflow and external temperatures (measured with Torque app and Bluetooth OBD2 scanner on several separate occasions and on that car the temp sensor is immediately above the thermostat), that means that once the car reaches temp the thermostat never closes but I don't overheat unless I'm atleast a half gallon low in the radiator and even then it's not by much.
so my point is it's the size of the radiator and fan capacity (and temp settings for engagement of fans) that set how hot the car will ultimately run, not the Thermostat, so in extreme temperatures like the desert you need bigger radiators with fans that move more air to create an adequate temperature drop to prevent the overheating.
There's not a single car that GM has ever built that can handle stop and go traffic like conditions in a 110*F desert
Yikes, you have posted some misleading/incorrect info here, this being a stand-out example.
Plenty of AZ members on this site with stock/mild cars that don't "overheat" in the desert. Even here in Chicago we sometimes see temps in the upper 90s/low 100s - the entire summer of 2012 was like this, and my stock cooling system '02 Z28 had ZERO issues with overheating.
With a fully "stuck" open tstat the coolant will NEVER get enough sitting time in the radiator to cool off, it will re-enter the engine already hot, thats when the end is near.
from one perspective this is true. but you need to consider the entire system, which is a closed system. and it's basic heat transfer, moving heat via the coolant from the cylinder head & block to the radiator where that heat is expelled into the air passing thru it.
how long the coolant spends in the radiator is a function of water pump speed, and length of the tubes making up the radiator. if coolant flows too fast and does not having enough time in the radiator to release enough heat, then you either need to increase the delta-t (temp difference between coolant temp and outside air temp) and/or move more air thru the radiator to make up for that. when the delta-t is not enough (coolant temp is 212° and outside air thru radiator is ??? 170°F or more?) and you cannot push enough air thru radiator to remove the required amount of heat... only then is your radiator size too small. 220° coolant vs 120° outside air is a delta of 100°F, that is more than enough in nearly all conditions and i would bet $1 no one after year 2000 has designed a car with too small a radiator. if there are overheat problems, its for other reasons.
i think you guys are silly for wanting to upgrade the oem ls1 radiator to the bigger lt1 version or whatever, thinking that the oem ls1 radiator does not have enough cooling capacity. if it doesn't, it's most likely contaminated internally and there's an insulating later of gook on the inside of the radiator or the exterior fins are clogged/smashed preventing airflow thru it... or you modified the car preventing sufficient airflow thru and away from the radiator. when you do the math, you would be surprised how small heat exchangers can be.
04-14-2016, 03:05 PM
Any such thing as too cool a thermostat? 
