Location of engine cooling fan temperature sensor

[Vincent998]

I'm curious about how the radiator cooling fans actually are controlled and when they operate. From the manuals, it seems that the controlling temperature sensor is on the right front of the motor. If that's correct, the fans might be controlled by the temperature of the coolant in the motor itself, not (as in some other cars) by the temperature of the coolant in the radiator. That would mean that the cooling fans might turn on while the motor is warming up, but before the thermostat opens. If true, the fans should shut off after the tstat opens, because then colder coolant from the radiator will be entering the motor. Is this correct? If not, how does the system operate?

If the above is true, I don't see the advantage of controlling the fans from motor coolant temperature rather than from radiator coolant temp, because (for instance) the fans might turn on when the coolant isn't even circulating (as in while motor is warming up). Again, if I am correct, why is the system set up this way?

 

[tmcphail]

Low / High temperature fan operation is controlled by Engine Coolant temperature. The actual temperature limits for this are set in the calibration. Factory cal data is below :

 

[Vincent998]

Thank you Torrie, I understand. But: my question is, coolant temperature from where? From the block or from the radiator? If the sensor reads coolant temp in the block, it seems to me that it will make a difference to when the fans turn on, at least until the entire system reaches some sort of equilibrium. The block heats up first, well before the radiator (coolant temp on warmup), and stays hot longer than the radiator (coolant temp on restart). So (at least theoretically) the fans could turn on before the thermostat opens (warmup) and turn on immediately on restart even if the radiator coolant is significantly cooler. On a different car, the dash gauge engine temperature sensor is on the intake manifold, but the fan temperature switch is on the radiator. What is the arrangement on the GT? What controls what (does the engine temp sensor control the fans, too)?

 

[tmcphail]

From the ECT sensor in the manifold

 

[RALPHIE]

From the ECT sensor in the manifold

As where it should be. The engine is what needs to be protected by the coolant. If it was controlled by coolant temperature in the radiator, there would be a significant lag in the response of the system to an over temperature condition. As opposed to a front-engined car (with the engine very close to the radiator), the GT has quite a bit of tubing between the engine and the radiators, containing a significant volume of coolant whivh would not be representative of the temperature at the engine. I wouldn't worry so uch about the startup characteristics, but I am very concerned about the engine temp when running on a track in only 2nd & 3rd gears which tends to drive up the temperature.

 

[twobjshelbys]

What is the flow rate of the coolant system?

 

[RALPHIE]

What is the flow rate of the coolant system?

Can't give you an answer, but I do know that it is conductance limited, as the coolant pump is capable of collapsing some of the interconnect hoses - which is why I have had installed the Accufab anti-hose-collapsing springs in the #2 car.

 

[Wwabbit]

Can't give you an answer, but I do know that it is conductance limited, as the coolant pump is capable of collapsing some of the interconnect hoses - which is why I have had installed the Accufab anti-hose-collapsing srings in the #2 car.

Yes. Springs are a must on the suction side for these cars if you run high rev conditions for extended periods.

 

[Indy GT]

For you new owners who have technical intrest in our car systems, one of the nice benefits our Ford GT design team did is to DOCUMENT (to the extent allowed by propriatary information) the engineering design aspects of our car. (Again, go find this information written by the vehicle designers on another supercar.)

Vincent998 you should read SAE publication 2004-01-1257, "2005 Ford GT-Maintaining Your Cool at 200 MPH", by Hill, Miller, Evans and Pollock. This has the technical information you seek.

All 11 technical papers on our current FGT vehicle as well as 5 bonus technical articles on the original Ford GT-40 are bundled in SAE publication PT-113.

Good reading for those with technical curiosity....

 

[Vincent998]

SAE Pubs on the GT

Thanks for the references! These look very interesting, especially the book ($90). However, they are not available without purchase. I will see if I can find a more or less local library that has them.

 

[RALPHIE]

...SAE publication 2004-01-1257, "2005 Ford GT-Maintaining Your Cool at 200 MPH", by Hill, Miller, Evans and Pollock....All 11 technical papers on our current FGT vehicle as well as 5 bonus technical articles on the original Ford GT-40 are bundled in SAE publication PT-113....

View attachment 29090​

http://books.sae.org/book-pt-113/

 

[RALPHIE]

In SAE paper 2004-01-1257, it states:

"The system required a minimum flow rate of 100 gallons per minute in the engine, and a minimum flow rate of 85 gallons per minute to the radiator." This, to achieve and maintain a target differential of 10-15° F across the engine.

 

[RALPHIE]

Here's a copy of 2004-01-1257:

 

[Beach-GT]

I added a switch to the fan relay so I can turn it on if I want to before the cooling system does. It helps on cool down before putting it back in the garage too. Since I just modified the relay, I can put a stock relay in the socket and take out the switch if I want to. I have never had a problem of the fan coming on by itself before the system was good and hot. Quite the opposite.

 

[RALPHIE]

I also tried to post a copy of SAE 2004-01-1252, "2005 Ford GT Powertrain – Supercharged Supercar," but, at 2.6 MB, it was too large to upload to the forum. For those interested, send mee a PM with your e-mail address, and I'll shoot it to you.

 

[BlackICE]

In SAE paper 2004-01-1257, it states:

"The system required a minimum flow rate of 100 gallons per minute in the engine, and a minimum flow rate of 85 gallons per minute to the radiator." This, to achieve and maintain a target differential of 10-15° F across the engine.

Since the engine cooling system is closed, doesn't the flow rate to the engine equal that to the radiator? :confused

 

[RALPHIE]

Since the engine cooling system is closed, doesn't the flow rate to the engine equal that to the radiator? :confused

I think most cooling systems have a bypass incorporated at the water pump, and there is some flow through the heating system (although that usually runs through the radiator after the heat exchanger).

 

[jcthorne]

I'm curious about how the radiator cooling fans actually are controlled and when they operate. From the manuals, it seems that the controlling temperature sensor is on the right front of the motor. If that's correct, the fans might be controlled by the temperature of the coolant in the motor itself, not (as in some other cars) by the temperature of the coolant in the radiator. That would mean that the cooling fans might turn on while the motor is warming up, but before the thermostat opens. If true, the fans should shut off after the tstat opens, because then colder coolant from the radiator will be entering the motor. Is this correct? If not, how does the system operate?

If the above is true, I don't see the advantage of controlling the fans from motor coolant temperature rather than from radiator coolant temp, because (for instance) the fans might turn on when the coolant isn't even circulating (as in while motor is warming up). Again, if I am correct, why is the system set up this way?

A couple of points about the GT (and all Ford modular V8s) that might help your understanding of how this works. First, the set point at which the cooling fan comes on is above the thermostat opening temp. Also realize that the thermostat temp is the temp at which the stat lifts off its seat, not when it is fully open.

Next, the stat is not on/off. Its a 3 way bypass valve type stat. When its fully 'closed' the coolant still circulates, just bypassing the radiator it goes back to the water pump inlet. As the stat opens, less is bypassed and more is sent to the radiator. When fully open, the bypass port is closed.

The two speed fan temp setpoints are programmable by tuning software.

Hope this helps.

 

[Vincent998]

It does indeed. All the info has been very useful.

Thanks to all who replied!