electric fan with coolant sensor ???

f8tlfiveo

My wife likes my spool and blow-off valve.
Aug 8, 2007
1,585
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Lancaster, PA
i bought a relay setup for my electric fan that has an actual thermostat not a therocouple that goes through the radiator fins. my question is -is there another place where i can mount the sensor other that rigging up somthing where the original coolant temperature sender is on the intake. the thermostat that i have is 3/8 NPT just like the stock one.
 
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How about something like this.
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i had that setup on my car first, the thermocouple on that setup isnt as accurate as the sensor that actually goes in the coolant but it worked fine until the relay got stuck and the fan didnt shut off. thats why i replaced it. i picked up the one i have for 32 bucks shipped to my house. maybe i will look into your idea but put it on the lower rad hose that way you cant see it.
 
maybe i will look into your idea but put it on the lower rad hose that way you cant see it.

I wouldn’t. The problem with putting it in the lower radiator hose, is that you're getting a far lower temperature reading than what’s actually exiting the engine since the coolant will have travelled through the radiator before reaching the sensor. Your fans might never come on as a result. You want it as close to the thermostat as possible to get the most accurate reading.

Does your thermostat housing not have an area suitiable for drilling and tapping the sensor?
 
Don't use a deadhead Tee for two temp senders, switches or sensors. The result is stagnant coolant that doesn't reflect the actual temp. You want each unit to be in the flow of coolant.
 
i didnt look at the thermostat housing yet but i could probrobly find a place. i am a toolmaker so i have access to the tools i need to do that.
Don't use a deadhead Tee for two temp senders, switches or sensors. The result is stagnant coolant that doesn't reflect the actual temp. You want each unit to be in the flow of coolant.
thats why i was looking for somewhere else to put the sensor i had a feeling it wouldnt get an accurate reading if it was on a tee. i cant put it in the radiator hose either because it will not have a ground for the sensor.
 
Oh, you can put the switch any place you like (a rubber line, etc). You would just solder a ground wire to the sender body and attach it to a clean ground location.
 
Oh, you can put the switch any place you like (a rubber line, etc). You would just solder a ground wire to the sender body and attach it to a clean ground location.
yes i was thinking about using the line that used to go up to the throttle body that i bypassed. i just have it looped underneath the throttle body now. do you think that line would be sufficient?
the thought of putting a ground wire on it had crossed my mind also.
 
Alternate placement for a temp gauge sender or electric fan thermo switch: This will allow you to keep the stock gauge for looks. Use the heater feed that comes off the intake manifold. Cut the rubber hose that connects the manifold water feed to the heater and splice in a tee adapter for the temp gauge sender. Be sure to use the same water feed line as the ECT sensor. That way you will get the most accurate temp readings.

Tee adapter info:
Make a pilgrimage to your local hardware or home supply center and get some copper pipe and a tee that fits the temp gauge sender. Solder two pieces of copper pipe onto a copper pipe tee with threads in the tee part. Find the correct brass fitting to match the temp sender threads to the tee fitting.

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Keep in mind that the capillary tube on mechanical temp gauges cannot be cut, shorted severely kinked or damaged in any way. It is one piece from the gauge to the temp bulb that goes in the engine coolant.

You main challenge will be getting the wiring or capillary tube through the firewall. Do not use the steering column exit path for any wiring or gauge plumbing. Make sure you seal any hole you drill in the firewall with high temp red silicone sealer.
 
Why would you put a temp switch in the middle of a hose when a stock 5.0 thermostat housing has a boos cast in it that can be easily drilled and tapped for a switch and that is the optimum place for a switch?
 
Why would you put a temp switch in the middle of a hose when a stock 5.0 thermostat housing has a boos cast in it that can be easily drilled and tapped for a switch and that is the optimum place for a switch?

The boss cast into the thermostat housing places the temp switch on the radiator side of the thermostat.
If you put the switch in the thermostat housing, it only shows the correct temperature once the thermostat opens up.

The best place is in the same coolant flow path as the ECT. The computer uses the ECT to tell it what then engine's coolant temperature is.
The drawing I posted shows how to put the thermostat switch in the ECT coolant path.
 
I wouldn’t. The problem with putting it in the lower radiator hose, is that you're getting a far lower temperature reading than what’s actually exiting the engine since the coolant will have travelled through the radiator before reaching the sensor. Your fans might never come on as a result. You want it as close to the thermostat as possible to get the most accurate reading.

Does your thermostat housing not have an area suitiable for drilling and tapping the sensor?

Yes, but if the coolant temperature exiting the radiator is below the temp that your fan is set to turn on, there is no need for the fan to kick on. It's only when the radiator is not able to cool the car when you need a fan (idling, stop and go trafiic, etc.). That's why DCC's are supposed to have their sensors put in a location toward the bottom of your Mustang radiator, when the coolant is flowing back into the engine.
 
Markus, that looks like a good solution to me. Where did you get it and how much did it cost? What's the part # and price for the temp sensor/switch?