hi all,
i fitted a 16" electric fan a couple of months back and ordered a digital adjustable thermostat, this had the sort you put in the top pipe from the rad but the question is, is this the right place for it?
as the standard stat opens the temp goes up (as expected) but ive found the fan comes on when doing 70mph+ as it is messuring the temp coming from the engine not from the rad, the standard temp gauge doesnt even get beyond 1/3 up so am i cooling the air to much? should i put the sensor in the bottom of the rad and set the temp at say 80c? that way if the temp of the water is too hot after going through the rad the fan will switch on


Thanks
Mark

 

I have mine at the bottom of the rad by the return to the engine, set to keep the temp at 180* as noted by the after market temp gauge.

 

that just seems to make more sense to me too, anyone else?

 

Your fan is for your RAD, so therefor you want the fan going on when the rad can't keep up. When the fan switches on it needs to help the rad cool the fluid going through it. Put your switch on the bottom rad hose so when your on the highway and the rad can keep up with the cooling requirments becuase of your forward motion the fan won't be on.

 

Here's an option I used for my dash gauge, but should work for the temp sensor:



Details contained in:

https://www.rx7club.com/1st-generation-specific-1979-1985-18/my-headlights-make-my-car-overheat-633150/

Ray

 

that was my thoughts, the next question i suppose is do you think 180f is cool enough to have the water going in?

 

i saw that when i was searching but that would give me the same reading, i know the stock gauges aren't great but i can get a idea of the temp just before the stock thermostat with that and use the digital one for the bottom of the rad, therfor messuring inlet and outlet temps (looking to fit another gauge at a later stage and would propably use this idea then)

Mark

 

Really, it doesn't matter. It is a closed loop. You can measure anywhere and just adjust the setpoint of the controller to get the fan to kick on when you need it. You are just measuring a single point as a reference.

You could say that the waterpump outlet/inlet to the rad is better because it will see a spike in temperature before the bottom of the rad will. Not much difference, but there is a delay.

I would put it wherever is easiest. If the t-stat was not adjustable, then it would be more important as to where you tap into.

Just do like Trochoid. Pick a spot and install. Use an aftermarket gauge in the stock position or back of waterpump. Adjust t-stat of fan as needed to maintain whatever temperature that you are shooting for (say 180*).

 

Right, it doesn't matter. There was a lot of "before the thermostat or after the thermostat" talk that made me nervous, but that T'stat stuck in the thermostat housing holds rock steady, agrees completely with the stock gauge that's stuck in the engine block all the time. So it comes down to what's easiest and what looks cooler. Which is what I like about mine:



more details at:

https://www.rx7club.com/1st-generation-specific-1979-1985-18/second-water-temp-sender-tip-installation-question-631760/page2/

 

how in the hell does ray keep it that clean?

 

I agree that the location probably isn't all that important, but the OEM location is typically in the coolant outlet area near the thermostat, so that's where I put mine. The back of the water pump has lots of meat there, and even a few threaded bosses, so you can screw a temp sensor in, if you decide to go that route. What may be more important is the relative set points of the thermostat and your fan switch. On mine (turbo 13B-RE), I used an OEM thermostat (180 deg) with a fan switch set to turn on at 210 deg and off at 190 deg. This ensures coolant is flowing before the fan is asked to assist, and also guarantees the fan will be off during normal cruising. If I had used a switch set to turn on at 195 deg and off at 175 deg, the fan would never shut off once it turned on.

 

I got mine from Black Dragon Auto and their instructions say to put it through the rad. right under the tube going to the waterpump(on top of the motor)

It is the one that you just stick through the blades of the rad right??

 

Don't know if it helps, but its where they say to put it....

 

mine is a zirgo one it does say to place it in the top rad pipe just questioning it really
im going to try a couple of things
A) move the sesnor closer to the termostat (still in the top pipe just the other end)
B) increase the switch on temp to 92c from 88c as the thermostat only fully opens at 90c

Mark

 

same setup i got ray, but i put mine in the back of the wp.

 

one vote for back of the waterpump housing

 

Yeah, just use the stock sensor.

 

???

The stock sensor is next to the oil pressure sensor. The temp switch on the back of the wp housing is for the choke hold/release on the 12As and talks to the ecu on the SE in regards to fueling. If installing in the back of the wp housing, it's better to tap a new hole.

I planned ahead when I built my engine and retapped the stock temp sender hole in the iron to take an aftermarket sender. That gives me a very accurate reading taken from the stock place in the engine. Retapping gray cast iron is not fun. Since it's so grainy, it's hard to cut clean threads.

 

thanks all but im gonna stick with the sesnor i have as i say the system works but i think it can be more efficent in terms of using the e fan when not needed, one solution is to change the switch on temp and another is the location of the sensor which is currently in the top hose at the rad end (going to move closer to the stat though)

Mark

 

The sensor on the back of the WP housing. Keeps the fan off until like 150-160* for quicker warm ups. Learned that from a friend over here, he's got it hooked up on his ride that way. Genius I say.

 

Genius, maybe, but that's too early for the fan to come on and you lose the function of the sensor for it's intended purpose.

 

the thermostat doesn't even open untill 180c so you wont be cooling anything, mine seems loads better went on a short trip today and the fan came on twice (in traffic) where as before it would of been on and off all the way

Mark

 

Splice it in, not cut it completely off

 

I agree that you don't want the fan coming on until after the thermostat opens (see my previous post). The temp, however, is 180 deg F, not 180 deg C.

 

Doh sorry im in the UK and we work with c not f

Mark