Car still running 190⁰+ even with 170⁰ thermostat

[Pentalab]

I have a 2010 GT, same as the OP. The 1st thing you do with a 2010/11/12 GT is toss the upper grille..and replace it with a 7 bar grille. The oem upper grille is 80% blocked off. With the 7 bar grille installed, it also eliminates the 2 x 90 deg bends into the 'snorkel' that in turn feeds the oem air box. Ok, now you have way more air going through the upper grille. The only downside to the 7 bar grille is.... it also deletes the oem upper fog lamps. My 2010 came with a 190 deg F T-stat. In my case, I have a small roush blower and also a B+M ( bar + plate type) auto tranny cooler.... plumbed in series with oem auto tranny cooler..and below it. I also have a 18" tall x 21" wide roush HE...right out in front of everything. I need all the air I can get.

In normal operation, in in 40 C ( 104 F) outside temps, like this recent heat dome event we had here in southern BC, the temp gauge on the dash is always to the left of vertical.

Idling, in the driveway.... coolant temps will rise to 206 F..then the low speed fan kicks in..and coolant temps drop down to 196 F...and low speed fan shuts OFF. Temp again rises to 206 F, low speed fan kicks in..and the cycle just repeats itself. On the road, even at 50 kph ( 30 mph)..the low speed fan is not on.
( high speed fan is set to kick in at aprx 213 F). Low speed fan not on, out on the hwy either.

In my case the 7 bar upper grille mod has worked out really good for the last 10 years...and looks a lot better. The actual measured velocity of the oem fan in both low and also high speed is not great at all. It's a lot of cfm, but the actual velocity is miniscule, like 20-25 mph.

Both the upper and lower grille openings on a 2010 is not very much.

 

[TheCrowdPlow]

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.

Bruh

 

[TheCrowdPlow]

I have a 2010 GT, same as the OP. The 1st thing you do with a 2010/11/12 GT is toss the upper grille..and replace it with a 7 bar grille. The oem upper grille is 80% blocked off. With the 7 bar grille installed, it also eliminates the 2 x 90 deg bends into the 'snorkel' that in turn feeds the oem air box. Ok, now you have way more air going through the upper grille. The only downside to the 7 bar grille is.... it also deletes the oem upper fog lamps. My 2010 came with a 190 deg F T-stat. In my case, I have a small roush blower and also a B+M ( bar + plate type) auto tranny cooler.... plumbed in series with oem auto tranny cooler..and below it. I also have a 18" tall x 21" wide roush HE...right out in front of everything. I need all the air I can get.

In normal operation, in in 40 C ( 104 F) outside temps, like this recent heat dome event we had here in southern BC, the temp gauge on the dash is always to the left of vertical.

Idling, in the driveway.... coolant temps will rise to 206 F..then the low speed fan kicks in..and coolant temps drop down to 196 F...and low speed fan shuts OFF. Temp again rises to 206 F, low speed fan kicks in..and the cycle just repeats itself. On the road, even at 50 kph ( 30 mph)..the low speed fan is not on.
( high speed fan is set to kick in at aprx 213 F). Low speed fan not on, out on the hwy either.

In my case the 7 bar upper grille mod has worked out really good for the last 10 years...and looks a lot better. The actual measured velocity of the oem fan in both low and also high speed is not great at all. It's a lot of cfm, but the actual velocity is miniscule, like 20-25 mph.

Both the upper and lower grille openings on a 2010 is not very much.

That's what I just noticed, the big "crimson chin" of the bumper sure blocks a good chunk of the rad.

 

[TheCrowdPlow]

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.

Everything that you quoted I agree with and how I picture a cooling system to work, maybe I just worded myself wrong. Idk how my question of why my 170⁰ thermostat acts like a 190⁰ thermostat turned into how a thermostat works. That wasn't my question. I just checked last night ambient 65⁰ with a cold start. The temperature consistently climbs until it hits 186⁰, then it take about 20% longer to reach 188⁰, then 50% longer to reach 190⁰ and that where it stays and doesn't climb anymore. I sat for 5 minutes with it idling at 190⁰ without the fans running, I see them to 200⁰+ to make sure. One would think that there is a 190⁰ thermostat in the car. So it's either A: the thermostat is faulty, B: the cooling system just sucks that bad that I'm at the limit of it at minimum load when at 190⁰. I'm not fucking retarded.

 

[Kobie]

Is it at all possible that you got the wrong thermostat? Maybe marked wrong or does not open per spec? Take it out and put it in a pan of water with a thermometer and watch when it opens?

 

[MrBhp]

Everything that you quoted I agree with and how I picture a cooling system to work, maybe I just worded myself wrong. Idk how my question of why my 170⁰ thermostat acts like a 190⁰ thermostat turned into how a thermostat works. That wasn't my question. I just checked last night ambient 65⁰ with a cold start. The temperature consistently climbs until it hits 186⁰, then it take about 20% longer to reach 188⁰, then 50% longer to reach 190⁰ and that where it stays and doesn't climb anymore. I sat for 5 minutes with it idling at 190⁰ without the fans running, I see them to 200⁰+ to make sure. One would think that there is a 190⁰ thermostat in the car. So it's either A: the thermostat is faulty, B: the cooling system just sucks that bad that I'm at the limit of it at minimum load when at 190⁰. I'm not fucking retarded.

I've always thought the cooling system was designed REALLY well. Ford engineers wanted the engine to run at 190, so they designed a system to run at 190. No matter what the t-stat has stamped on it. Pretty freakn genius in my opinion. As far as the implementation of the design however, not all of it is well done. Such as the fan overloading the BEC and frying the surrounding territory.

 

[Laga]

When I first installed my SC, I went with a 180°F thermostat. The car ran at 190-195 around town with performance radiator and water pump. It is not driven in the winter. After two years, I then switched to a 190°F thermostat. It now runs at 190-195.

 

[07 Boss]

Everything that you quoted I agree with and how I picture a cooling system to work, maybe I just worded myself wrong. Idk how my question of why my 170⁰ thermostat acts like a 190⁰ thermostat turned into how a thermostat works. That wasn't my question. I just checked last night ambient 65⁰ with a cold start. The temperature consistently climbs until it hits 186⁰, then it take about 20% longer to reach 188⁰, then 50% longer to reach 190⁰ and that where it stays and doesn't climb anymore. I sat for 5 minutes with it idling at 190⁰ without the fans running, I see them to 200⁰+ to make sure. One would think that there is a 190⁰ thermostat in the car. So it's either A: the thermostat is faulty, B: the cooling system just sucks that bad that I'm at the limit of it at minimum load when at 190⁰. I'm not fucking retarded.

Apparently you are. YOUR CAR WILL RUN AT 190* NO MATTER WHAT THERMOSTAT YOU PUT IN THERE. IT SETS THE LOWEST TEMPERATURE WHERE YOUR COOLING SYSTEM OPERATES. THE THERMOSTAT HAS NOTHING TO DO WITH HOW HOT IT GETS! What part of that don't you understand?

 

[MrBhp]

Look dude. We don't use the word "retarded" around here. It's offensive and hateful.

The preferred word is "gay".

 

[Pentalab]

That's what I just noticed, the big "crimson chin" of the bumper sure blocks a good chunk of the rad.

I installed the CDC ( Classic design concepts) lower spoiler on my 2010 GT. Looks good, robust, and will scoop up plenty more air into the lower grille. While I was at it, I also installed the CDC brake duct kit....which is designed to go with their lower spoiler. It uses 2 x new 14" dust shields..and 2.5" ID silicone rubber hoses. I'm using the oem 12.4" front rotors and 2 x piston calipers ( but with new slotted rotors, SS brake lines, and german brand brake fluid..and also Hawk HPS pads). No more brake stink, if being really aggressive.

 

[Juice]

Actually, the cooler tstat/no tstat myth goes back to carburated days. And it is not a myth. My first car was a 68 mustang, 4bbl 302. Guy I got it from had removed the tstat and put on a monster 4 barrel holly double pumper. Ran like a raped ape, pass anything but a gas station. (Single digit mpg's)
I had no heat in the winter, and the temp guage never moved much off cold. Put in a tstat to have heat, and now the car was way over carbed and would run like shit.

Moral of the story, tstats control MINIMUM engine temp.
A larger radiator will keep the tstat closed more.
Im still trying to figure out why a 180 made my car run at 210 and fan was coming on at highway speeds. A second 180 does seem to work, but no difference visible on the temp guage.
I literally see LESS cooling fan operation with the stock 195. Which is completely backwards.
As a side note, the amount of HP you make determines how big a radiatorr you need. OEMs spec the smallest radiators that will do the job, its basic economics.

 

[pass1over]

and german brand brake fluid..

because everyone knows the Germans make great stuff

 

[Pentalab]

because everyone knows the Germans make great stuff

ATE- blue...and also ATE-200. Superb stuff. My German made Miele upright vac cleaner is superb too..... triple the suction of any shop vac

 

[crjackson]

I'm not fucking retarded.

Apparently you are.

Crowd, you are wrong. You can’t seem to grasp the way it works. Everything these guys have told you is correct. Just accept it.

Think of it like this if it helps…

Your cooling system is designed for two temperature points…

1) Low temperature regulation > thermostat
2) High temperature regulation > radiator, air flow, water flow

That’s a simplified breakdown, and removes some of the variables, but that’s it in a nutshell. Very simple to understand.

 

[Shakn68]

Most modern engines, for the last 30 years have been designed to run at around 190-200 to provide the best efficiency in regards to the emission systems and exhaust output.

 

[Lime1Gt]

The thermostat is there, as said before, to allow the engine to heat quicker for more efficient operation by heating a smaller volume of coolant in the engine. The engine coolants heat also serves to warm the heater core.
The thermostat also helps to regulate cold radiator coolant to the hot engine coolant as the stat slowly opens. If the stat has too low of setting or is stuck open the added volume of cold radiator coolant will pull heat from the engine and it will take longer to make the best operating temperature. This is clearly seen and felt {heater core} if living in cold climates. The thermostats temp rating tries to maintain that minimum operating temperature in cold climates by opening and closing as required. Once the engine reaches operating temperature, think of the thermostat as not allowing the engine to drop below it's rating in operation.
Engine coolant mix may also affect engine temperature as antifreeze is not a good heat transfer chemical. 50/50 mix is ideal whereas 70 AF to 30 water is a poor transfer of heat but may be required in extreme cold.

 

[DieHarder]

The thermostat is there, as said before, to allow the engine to heat quicker for more efficient operation by heating a smaller volume of coolant in the engine. The engine coolants heat also serves to warm the heater core.

The thermostat also helps to regulate cold radiator coolant to the hot engine coolant as the stat slowly opens. If the stat has too low of setting or is stuck open the added volume of cold radiator coolant will pull heat from the engine and it will take longer to make the best operating temperature. This is clearly seen and felt {heater core} if living in cold climates. The thermostats temp rating tries to maintain that minimum operating temperature in cold climates by opening and closing as required. Once the engine reaches operating temperature, think of the thermostat as not allowing the engine to drop below it's rating in operation.

Engine coolant mix may also affect engine temperature as antifreeze is not a good heat transfer chemical. 50/50 mix is ideal whereas 70 AF to 30 water is a poor transfer of heat but may be required in extreme cold.

Can attest to the thermostat regulating the low temp point. In winter up here (Great Lakes) it can get very cold. Have a DOB setup and had an instance where my thermostat had a gap around the edge (missing gasket) which allowed water to pass around the thermostat in effect acting as if it was stuck open. Had to drive down to DC and saw my temps go all the way down. Not sure what temp it reached but I was concerned I'd damage the engine. Turned out to be okay. Later I found a gasket that would fit and temps went back to normal. Still, taught me a lesson.

Agree with CRJackson and others.... The system was designed for a certain heat load/rating. Changing out your thermostat isn't going to make a difference temp wise on the high end. Changing out other items (radiator; adding elec water pumps; changing the temp set points for the fans) can keep your temps down but limited in effectiveness unless you go extreme (ice chests; other cooling solutions) but typically they're not practical for a street car. Still, it's your money.

 

[Pentalab]

The thermostat is there, as said before, to allow the engine to heat quicker for more efficient operation by heating a smaller volume of coolant in the engine. The engine coolants heat also serves to warm the heater core.
The thermostat also helps to regulate cold radiator coolant to the hot engine coolant as the stat slowly opens. If the stat has too low of setting or is stuck open the added volume of cold radiator coolant will pull heat from the engine and it will take longer to make the best operating temperature. This is clearly seen and felt {heater core} if living in cold climates. The thermostats temp rating tries to maintain that minimum operating temperature in cold climates by opening and closing as required. Once the engine reaches operating temperature, think of the thermostat as not allowing the engine to drop below it's rating in operation.
Engine coolant mix may also affect engine temperature as antifreeze is not a good heat transfer chemical. 50/50 mix is ideal whereas 70 AF to 30 water is a poor transfer of heat but may be required in extreme cold.

AFAIK, 50/50 mix is good down to -40 deg F. That's pretty cold to be...'tooling' about in a mustang.

On a side note, DOB recommends the use of a 160 deg F T- stat. Perhaps for drag racing, that concept might have some merit. The oem 190 deg F T- stat works good.

 

[Juice]

You guys have the mix ratio wrong.
More water less antifreze is better for heat transfer. Best heat transfer is pure water. As you reduce antifreeze %, the freezing point of the mix rises. Thats the trade off.
How cold does it get determines how much antifreeze is needed to keep the coolant from turning into ice.
If you lived in an area where it never froze, you could run straight water, but than there is that peski corrosion protection missing.
Pure antifreeze without water has the worst heat transfer, and even boils at a lower temp than a mix.

 

[Laga]

AFAIK, 50/50 mix is good down to -40 deg F. That's pretty cold to be...'tooling' about in a mustang.

On a side note, DOB recommends the use of a 160 deg F T- stat. Perhaps for drag racing, that concept might have some merit. The oem 190 deg F T- stat works good.

I used to drive my 1979 Mustang V6 in -30°F in North Dakota. I had a 100 mile round trip for work. Even with the grill blocked off it never got hit enough to clear the inside of the windshield. Oddly, whenever it was in the 35°F-40°F range with high humidity, the carburetor would ice up.