Car still running 190⁰+ even with 170⁰ thermostat

[TheCrowdPlow]

So I installed a 170⁰ thermostat and set the low and high speed fans at 186⁰ and 190⁰ as instructed a couple months back in my 2010 GT. I never actually checked with my handheld tuner the coolant numbers till now and even when cruising down the highway on a 70-75⁰ day the handheld tuner showed 192-196⁰ coolant temps. When coasting to a stop it will go down to only 190⁰, and I can hear the high-speed fan working and will only turn off to low speed after maybe a minute or 2 idling. I don't think I've ever noticed the low speed fan ever turning off, it seems to always be on once the car is warm. When doing a WOT pull on the highway coolant temps will go above 200⁰.
I even noticed my water temp gauge in the car has always gone up to the same area (almost vertical) as it did before with the stock 192⁰ thermostat that was in the car.
Is something in the tuner not correct or do I have some other cooling issue?

 

[Dino Dino Bambino]

Your coolant temperatures are normal so there's no issue. A lower temperature thermostat just allows coolant to circulate through the radiator earlier than normal as the engine's warming up. During the winter months your engine may run at 170*F but higher ambient temperatures will cause the engine to run hotter.
The 4.6 3V was designed to run at 190-200*F for optimum fuel efficiency and reduced emissions. Therefore I suggest you set the high speed fan mode at about 210*F, the low speed fan mode at about 200*F, and have the fan switch off altogether at 190*F.

 

[TheCrowdPlow]

Your coolant temperatures are normal so there's no issue. A lower temperature thermostat just allows coolant to circulate through the radiator earlier than normal as the engine's warming up. During the winter months your engine may run at 170*F but higher ambient temperatures will cause the engine to run hotter.
The 4.6 3V was designed to run at 190-200*F for optimum fuel efficiency and reduced emissions. Therefore I suggest you set the high speed fan mode at about 210*F, the low speed fan mode at about 200*F, and have the fan switch off altogether at 190*F.

Ya I understand what you are saying, but I still want to know why with a 170⁰ thermostat the coolant temp still is in the 190's. It shouldn't be like that unless it's a faulty thermostat no?

 

[Dino Dino Bambino]

Ya I understand what you are saying, but I still want to know why with a 170⁰ thermostat the coolant temp still is in the 190's. It shouldn't be like that unless it's a faulty thermostat no?

There's nothing wrong with the thermostat. The rated opening temperature is merely the minimum temperature the engine will operate at once it's fully warmed up. The idea is to allow the engine to warm up as quickly as possible and prevent it from running too cool, especially in the winter months. It doesn't necessarily mean that the engine will run at 170*F just because you have a 170*F thermostat. In the summer months the engine is likely to run hotter and that's fine. Just adjust your fan temperature settings and you'll be good to go.
Even if you removed the thermostat altogether (and that's a bad idea BTW) your engine would still run at 190-200*F in the summer 'cause it was designed to do so.

 

[GlassTop09]

Ya I understand what you are saying, but I still want to know why with a 170⁰ thermostat the coolant temp still is in the 190's. It shouldn't be like that unless it's a faulty thermostat no?

1st off....what Dino said.

To be more specific though, the reason why you're seeing what you're seeing has nothing to do w\ the thermostat but everything to do w\ radiator & radiator fan cooling capacity. If you're still using the same radiator & radiator cooling fan\shroud along w\ the same water pump (read coolant circulation rate thru engine & radiator here which affects coolant retention time thus heat transfer rate from radiator core to airflow passing thru it) prior thermostat changeout then the engine operating temps will still remain close to the same operating temps regardless of the thermostat's lower opening temp due to no effective increase in cooling capacity, which can only be achieved by increasing the size of the radiator being used & increasing the cooling fan's CFM airflow rate w\o excessively increasing the amount of amps draw (another reason why BEC's get burned...spend too much time running fan in hi speed mode trying to make up for a lack of adequate radiator cooling capacity) by using fans w\ more blades at same pitch to increase airflow CFM rate thru radiator to further increase low speed cooling capacity but using trap doors in fan shroud to allow air at hi speed to bypass the cooling fan itself (fan becomes a restriction to air flow movement thru it) to maintain a higher overall system cooling capacity rate. Once this is done in addition to using the lower temp thermostat then you'll see more of what you want\expect to see concerning engine operating temp ranges.......but why would you want to give up engine operating thermal efficiency....unless your engine is FI-equipped, using a lower temp range thermostat is really pointless & actually very counterproductive to engine operating efficiency AND longevity IMHO.

You'd be much better off to stick w\ the OEM 195*F thermostat then increase radiator size\radiator cooling fan size & capacity as described to maintain effective cooling at\close to the 195*F thermostat open temp thruout all engine operating conditions.

In the end the choice is yours to make............

Hope this helps.

 

[Juice]

I have observed same in my coyote. First 180* (NAPA) actually made the car run hotter, and fan was coming on at 60mph. I put in another, (Stant) This second one does run 5* cooler.
Air was bled from cooling system.
I have a Mishimoto 3 core radiator.
I should have put the stock tstat back in.

 

[TheCrowdPlow]

1st off....what Dino said.

To be more specific though, the reason why you're seeing what you're seeing has nothing to do w\ the thermostat but everything to do w\ radiator & radiator fan cooling capacity. If you're still using the same radiator & radiator cooling fan\shroud along w\ the same water pump (read coolant circulation rate thru engine & radiator here which affects coolant retention time thus heat transfer rate from radiator core to airflow passing thru it) prior thermostat changeout then the engine operating temps will still remain close to the same operating temps regardless of the thermostat's lower opening temp due to no effective increase in cooling capacity, which can only be achieved by increasing the size of the radiator being used & increasing the cooling fan's CFM airflow rate w\o excessively increasing the amount of amps draw (another reason why BEC's get burned...spend too much time running fan in hi speed mode trying to make up for a lack of adequate radiator cooling capacity) by using fans w\ more blades at same pitch to increase airflow CFM rate thru radiator to further increase low speed cooling capacity but using trap doors in fan shroud to allow air at hi speed to bypass the cooling fan itself (fan becomes a restriction to air flow movement thru it) to maintain a higher overall system cooling capacity rate. Once this is done in addition to using the lower temp thermostat then you'll see more of what you want\expect to see concerning engine operating temp ranges.......but why would you want to give up engine operating thermal efficiency....unless your engine is FI-equipped, using a lower temp range thermostat is really pointless & actually very counterproductive to engine operating efficiency AND longevity IMHO.

You'd be much better off to stick w\ the OEM 195*F thermostat then increase radiator size\radiator cooling fan size & capacity as described to maintain effective cooling at\close to the 195*F thermostat open temp thruout all engine operating conditions.

In the end the choice is yours to make............

Hope this helps.

Not what I wanted to hear, I was also thinking just not a big enough radiator so it can't cool quick enough. Which imo is a stupid design, most vehicles I've owned have a big enough cooling system that when you do change thermostats to cooler ones your temps do actually go down. Kinda disappointing honestly.

 

[TheCrowdPlow]

There's nothing wrong with the thermostat. The rated opening temperature is merely the minimum temperature the engine will operate at once it's fully warmed up. The idea is to allow the engine to warm up as quickly as possible and prevent it from running too cool, especially in the winter months. It doesn't necessarily mean that the engine will run at 170*F just because you have a 170*F thermostat. In the summer months the engine is likely to run hotter and that's fine. Just adjust your fan temperature settings and you'll be good to go.
Even if you removed the thermostat altogether (and that's a bad idea BTW) your engine would still run at 190-200*F in the summer 'cause it was designed to do so.

That's interesting, only other question I've got is why do other 3v owners say they noticed a big drop in coolant temps with a 170⁰ thermostat. Saying it only get to high 170's then the tstat is fully open as they see coolant temps drop? Unless they aren't mentioning that they don't have the stock radiator anymore? I just find it out that Ford would engineer a rad so small that it wouldn't get below 190⁰. The 2010 even has a bigger coolant capacity, and makes less power meaning less heat that the 2011-14's. And they see a differance in going to a lower temp tstat.
I find that VERY odd if that's the case.

 

[Dino Dino Bambino]

That's interesting, only other question I've got is why do other 3v owners say they noticed a big drop in coolant temps with a 170⁰ thermostat. Saying it only get to high 170's then the tstat is fully open as they see coolant temps drop?

It depends on the time of year. In the winter months it'll probably run at 170*F even with the stock radiator but it's possible other owners may have also upgraded to a thicker radiator with more cooling capacity.
Ford didn't want the engine running below 190*F in order to get the best possible gas mileage and minimize HC/CO/NOx emissions.

 

[07 Boss]

Ya I understand what you are saying, but I still want to know why with a 170⁰ thermostat the coolant temp still is in the 190's. It shouldn't be like that unless it's a faulty thermostat no?

Uhhhh...... if didn't have a thermostat at all it would run at the same temperature. The thermostat has nothing to do with how hot your car runs only when it allows coolant to flow. If you want to run lower temps you have to increase coolant flow and/or increase radiator cooling capacity. Putting in a lower temp thermostat will only prevent your car from warming up as quickly.

 

[07 Boss]

That's interesting, only other question I've got is why do other 3v owners say they noticed a big drop in coolant temps with a 170⁰ thermostat. Saying it only get to high 170's then the tstat is fully open as they see coolant temps drop?

Because most people don't have a clue as to what they are talking about.

Best cooling mod I did was to swap in an electric H2O pump. My gauge never gets to the middle vertical position even when I'm running her hard in the high desert. It was 108* yesterday. I've even seen my gauge drop while sitting in the staging lanes. Most cars will get hotter idling with no air flowing because not much coolant is getting circulated, while an electric pump is flowing at full all the time.

 

[TheCrowdPlow]

Uhhhh...... if didn't have a thermostat at all it would run at the same temperature. The thermostat has nothing to do with how hot your car runs only when it allows coolant to flow. If you want to run lower temps you have to increase coolant flow and/or increase radiator cooling capacity. Putting in a lower temp thermostat will only prevent your car from warming up as quickly.

That's not true unless the radiator is the limiting factor, the thermostat had a function and it does it function, which is regulate at what temperature the coolant is. There is a reason why it's there. It also depends on where the thermostat is located.

 

[TheCrowdPlow]

It depends on the time of year. In the winter months it'll probably run at 170*F even with the stock radiator but it's possible other owners may have also upgraded to a thicker radiator with more cooling capacity.
Ford didn't want the engine running below 190*F in order to get the best possible gas mileage and minimize HC/CO/NOx emissions.

Makes sense, maybe since I've got UDP too that is contributing some too. I don't have cats anymore so emissions is a non issue, and the little gas milage that I will lose, is so small that I don't even notice it. It's funny cause wernt the 05 and 06 mustangs a 180⁰ tstat?

 

[Kobie]

Another thing to take into consideration is venting the air from under the hood. Possibly use something like the Tiger Racing hood.

 

[Pentalab]

That's not true unless the radiator is the limiting factor, the thermostat had a function and it does it function, which is regulate at what temperature the coolant is. There is a reason why it's there. It also depends on where the thermostat is located.

Nope, the T stat prevents water from circulating in the radiator (only the block) until the water temp gets up to 160/170/190 F or whatever ur T stat is. The T stat doesn't snap open asap either, but opens gradually. It's function is to get the eng coolant temp up to proper operating temp...quickly.

EG:, if it was winter, and below freezing, and a 160 F T stat is used, coolant will start to circulate through the rad once the block coolant temps hits 160 F. Then it takes quite a long time to get up to 190-200 F.

If the T stat was removed..and it was summertime, and outside temps were 100F, the coolant temps would hit 190-200 F pretty quick.

The only thing regulating the coolant temps once the T stat opens up is the air through the rad and / or the fan speed. Off/low speed / high speed.

160F is way too cool for eng coolant temps. Talk to any road course racer, and they will tell you that there is no difference between a 160 / 190 F T stat...the coolant temps will be > 200F. To improve rad performance you really don't require a bigger rad, but more airflow through the existing rad. All that air going through the front grilles goes through the rad, then gets jammed up inside the engine bay...and exits out the bottom, on either side of the block. And with that big bottom cover installed, it doesn't leave a lot of egress. Vented hood allows for more air to escape..out the top.... so u now have a parallel path for air to exit.

 

[Laga]

The idea of using a cooler thermostat is outdated concept from the OBDI days. If you kept the engine cold, the early ECM’s would/could be tricked into staying in open loop. This sometimes made the fuel/air ratio richer. I’m not really sure if it ever made more horsepower or more of a placebo effect.
With today’s cars. It better to stick with stock temps.

You would really understand how a thermostat works if you ever drove in -30°F or colder temps. The thermostat would be constantly opening and closing to the point there would never be heat in the car. You had to cover the front of the radiator to eliminate airflow through it just to get the engine up to normal temps and have heat in the car.

 

[TheCrowdPlow]

The idea of using a cooler thermostat is outdated concept from the OBDI days. If you kept the engine cold, the early ECM’s would/could be tricked into staying in open loop. This sometimes made the fuel/air ratio richer. I’m not really sure if it ever made more horsepower or more of a placebo effect.
With today’s cars. It better to stick with stock temps.

You would really understand how a thermostat works if you ever drove in -30°F or colder temps. The thermostat would be constantly opening and closing to the point there would never be heat in the car. You had to cover the front of the radiator to eliminate airflow through it just to get the engine up to normal temps and have heat in the car.

I live in northern Canada, I know all about how to keep an engine warm. It also gets hot and always humid here in the summer, so I've seen my share of hot vehicles too. If I used my diesels at work in the winter I would switch them back to the stock thermostats, but I swapped them to lower set thermostats cause they are used in the warm months only, and the lower thermostats DO make a difference.
My mustang is the same deal, as soon as snow fall comes, I park it.

Edit: actually there will still be heat in the car even with the thermostat opening and closing in extreme cold temperatures without a winter front, cauae most vehicles heater cores come from pre thermostat coolant and not post. My 08 P71 has a partially stuck open thermostat and in -40⁰ temperatures it still put out some heat, it wasn't hot, just warm. Reminds me I gotta fix that before winter.

 

[07 Boss]

That's not true unless the radiator is the limiting factor, the thermostat had a function and it does it function, which is regulate at what temperature the coolant is. There is a reason why it's there. It also depends on where the thermostat is located.

No, afraid not. The thermostat does nothing to regulate the coolant temp. You can change thermostats all you want it will have zero effect on the operating temp of your motor. Look this is how it works. You start your car and it heats the coolant in your motor. When it reaches a certain temperature the thermostat opens and the coolant is allowed to flow between the radiator and the block. The temperature will continue to rise until an equilibrium is met between the engine heating the coolant and the radiator/fan cooling it back down. That equilibrium is your operating temp. If you blow more air over the radiator or increase the flow of coolant, that is the only way to effect the operating temp of your motor. Pull your thermostat, that will be like running a 0* thermostat. I bet your motor still gets up to 190 or wherever it is now.

 

[07 Boss]

I live in northern Canada, I know all about how to keep an engine warm. It also gets hot and always humid here in the summer, so I've seen my share of hot vehicles too. If I used my diesels at work in the winter I would switch them back to the stock thermostats, but I swapped them to lower set thermostats cause they are used in the warm months only, and the lower thermostats DO make a difference.
My mustang is the same deal, as soon as snow fall comes, I park it.

Edit: actually there will still be heat in the car even with the thermostat opening and closing in extreme cold temperatures without a winter front, cauae most vehicles heater cores come from pre thermostat coolant and not post. My 08 P71 has a partially stuck open thermostat and in -40⁰ temperatures it still put out some heat, it wasn't hot, just warm. Reminds me I gotta fix that before winter.

Dude, I'm sorry, that's just not the way it works. You need to do a little mechanics 101 again.

 

[07 Boss]

Here, I just copy and pasted from the first article that came up.


The Function of the Thermostat & Cooling System Basics
The biggest misunderstanding about thermostats is that people believe they make the engine run cooler. They don't necessarily do that. The cooling system and load on the engine determines how hot the engine gets, the thermostat fully open will still be the mercy of the coolant system's ability to remove heat.

The thermostat can only determine when the cooling system is allowed to start cooling the engine. It sets a floor, not a ceiling on engine temperatures.

In liquid cooling systems, the ability to cool is determined by a number of factors, but the basic keys are the surface area of the radiator (how big/how many small fins), the air flow through the radiator (fans on/off, speed of car), and how quickly or slowly the cooling fluid goes through the radiator.

The thermostat is there primarily to help the engine warm up in the morning. As we discussed in a previous article, the engine is designed to operate at it's operating temperature. Most engine wear occurs when the engine is cold, once it's warmed up there is very little wear in a healthy engine. Thus, we definitely want to run a thermostat to allow the engine to warm up as quickly as possible until it reaches our desired and designed operating temperature.

What they're used for
So what then would a low temperature thermostat accomplish? Not much.

Around town and in the pits, you warm up faster than no thermostat at all, but you will take a while to warm up from 160 to 180 for example. You will get there however, especially on warm days, the only difference is you're trying to cool the car off as it's trying to warm up. As a mater of fact, if you sit there at idle, the temp will go up until the radiator fans kick on since radiators are poor cooling devices without air flow. In other words, sitting still, the thermostat opening temperature doesn't matter much at all.

Once you're moving, on the highway, with a 160 degree thermostat on a cooler day you could be cruising at 160-180 degrees (opening temp->designed operating temp). This is possible because the load on the engine is low and the outside temps are low. Therefore, the thermostat opening temp maters somewhat here. If you're coasting down a mountain, it will be a certainty that your coolant will reach the thermostat minimum if you coast long enough.

The problem with a low temp thermostat then for regular driving is that there are times when the car will be running at a temperature lower than it's design intended. The result is increased wear on the engine's internals. It's essentially the same as if you assembled the engine with clearances tighter than designed for because you didn't follow the directions or your tools were not calibrated properly.