sharingan 19

iTrader: (16)

Well damn!
I was about to call a tow truck when my temps got up to 226* after I swapped my (fc) thermo switch which comes on @ 207* w/ a subaru switch with a shorter element that supposedly comes on at 194 and off at 185. But apparently its ok to run that hot...

eViLRotor

iTrader: (2)

After installing the thermoswitch, the most drastic improvement was how much less flashburn you get on your face when you open the hood after a long drive

The e-fans certainly do come on more frequently, especially the aftercool function. It happens everytime is shut down th car.

I'll take lower batter life for prolonged harness and plastic component life!

live2drive15

iTrader: (4)

Yea what's harder to fix? Broken vacuum lines, crispy wires, blown engine OR a battery lol

wstrohm

The provision of ground to the return side of the fan motors' windings enables, i.e. allows the motor to run when its "B" terminal gets power. The fan motors' "B" terminals get power from the Fan Control Module via the relays #2 and #4 when the FCM's terminal "E" goes low, which is (probably) caused by its terminal "C" going low, which is what happens when the switch closes.

In other words, closing the switch turns on the fans. (This would not happen if the Fan Control Module was not present.)

mefarri

iTrader: (2)

Good info

1QWIK7

iTrader: (33)

I always pop the hood. I practiced this religiously since i first owned the car.

There has never been a time where i just shut the car off and left. Either i had the fans running for nearly 5 minutes after shutdown or the hood was popped. Sometimes even both depending on the driving and/or ambient temp.

You'd be amazed at how fast the temps rise when you shut down.

I once parked at a rest stop on the turnpike. It was about 85 degrees outside. Pretty warm but not bad. After i shutdown, i ran the fans for 2 minutes, just to bring temps down a bit to buy me time so when i come back, the temps arent insanely high lol

Ran fans til temp gauge read 185F. Shut car down, went inside rest stop and went to ATM. Got some cash and walked right out to the car. I'd say i literally took 3-4 minutes TOPS.

Got back in the car, turn key to ACC and temp gauge showed 215F LOL

I was like wtf? A 30 degree increase in like 4 minutes? Thats insane. I was driving for about 30 minutes prior to the rest stop with some boosting but still. I think thats still crazy.

So for the people who think popping the hood after each drive is a waste and stupid, think again.

wstrohm

Too bad there isn't a supplementary electric coolant pump at the water pump inlet that would run when ignition is off and fans are running.

1QWIK7

iTrader: (33)

Maybe we could mimic other manufacturers and incorporate it to work with the FD system.

When i had my audi tt, the water pump would run when the car was off. I dont remember how long, i think 5 minutes?

Id say this would be useful for people who daily drive the car and dont have the luxury and time to just sit in the car with the fans on or with the hood up. But even if they did that, they still have hot coolant just sitting anyway so...

JM1FD

iTrader: (1)

I had the same idea after seeing the same electric pump on my TT...problem is, you'd need an extra nipple somewhere on the radiator to put the pump in an effective flow path. It would probably be easier to just ditch the stock belt driven pump and go to a large electric water pump.

ArmenMAxx

iTrader: (21)

Just FWI.. with my stock cooling system minus ast, fresh coolant, and fans set to turn on at 84c. My car would not pass 90c even in the hottest weather with normal driving.

Now with a V-mount, it dosent really pass 90c on the track during 95f weather. 104c or 220f seems kinda high for non-spirited driving conditions even at 108degrees ambient.

wstrohm

ArmenMAxx,

Why and how set the fans to come on at 84°C, when the thermostat is not even fully open at that temperature? Fully-open on the stock thermostat is 95°C. Why not let the water pump do the work until its capability is fully maxed out at 95°C, then set fans to come on just above that temperature. The FC fan thermoswitch closes at 97°C, which makes sense... to me, anyway.

ArmenMAxx

iTrader: (21)

I dont know when the thermostat is fully open, but I do know that the cooler the car runs the better and if my car holds 84c during track days with cooler ~80degree farenheit ambient temps, im happy. Setting the fans to 84c helped a lot and I recommend it to everyone (dosent have to be 84, I would recommend between 84-88c).

wstrohm

FYI, from the "Mazda RX-7 1994 Workshop Manual," page TD-4:

Opening temperature 80.5 - 83.5°C (177 - 182°F)
Full-open temperature 95°C (203°F)
Minimum full-open lift 8 - 10 mm (0.31 - 0.39")

Holding temps to 84°C by any means will severely restrict coolant flow, unless a lower temperature thermostat has been installed. (Maybe that's OK, but maybe not.)

2slo4my7

iTrader: (3)

Ah now I understand why the fans turn off at 203f.

Thanks!

Speed of light

iTrader: (8)

Thermostats don't need to fully open in normal operation. They are intended to restrict the coolant flow through the radiator in order to hold the coolant temperature at or near the thermostat's opening temp. If you have proper--i.e., enough airflow and heat rejection capacity--then you temps should sit just above the opening temp and increase only slightly with additional load. (And based on my own experience, this is pretty much what happens with a properly ducted v-mount setup.)

Accordingly, the thermostat will regulate temps while the car is moving (with sufficient velocity to establish airflow) and the fan switch is intended to provide airflow while the vehicle is moving slowly or at rest.

The stock thermostat (and many normal temp stats) start to open at about 82 deg C. So, ArmenMaxx, you car at 84 deg is doing just what I would expect it to do.

wstrohm

Agreed, in fact I agree with all you wrote. My point was that firing up the fans at 84°C pretty much overrides the thermostatically-controlled coolant system. As you wrote, if the system is working properly, when the car is moving the coolant temps should not go above that set by some intermediate value of thermostat opening. (The Miata normally runs with its thermostat open about halfway.) Additional cooling from the fans is not needed unless coolant temp goes above 95°C.

Bakemono7

iTrader: (13)

I have a question. What does the FC thermoswitch trigger normally, since it does not come equipped with electronic fans?

wstrohm

Not familiar with the FC, but would guess that the signal from the FC's thermoswitch is sent to a fan relay coil, which responds by switching on the FC's fan(s?). Anyway, that's how it worked on the '90 - '93 Miata.

arghx

iTrader: (3)

turbo and automatic FC's had a small auxiliary electric fan and a simple fan control module which relied on the thermoswitch. These engines have the thermostat housing tapped for the thermoswitch. Most cooling was still done by the clutch fan. 5 speed non turbo models didn't even have a thermoswitch or auxiliary fan and the thermostat housings were not tapped for the thermoswitch.

Bakemono7

iTrader: (13)

Thanks for the info boss. Very informative.

RotaryEvolution

iTrader: (30)

pffft, it hits 108 regularly here in the valley..

Ernesto13B

iTrader: (4)

Ok, I put the FC Thermoswitch to the ultimate test... SevenStock!!! My temps stayed around 180-190 during the entire 7 hour trip to Irvine, CA. On the Grapevine, with 90 degrees outside, my temps started slowly creeping to about 200's and I saw 210F, but I watched the gauge carefully, then temps started decreasing again rapidly back down to 180F, I'm very pleased with the thermoswitch!!

wstrohm

Ernesto13B, did your fans come on? If not, the FC thermoswitch did not affect your temps. My turbo'ed Miata's temperature did pretty much the same thing going southbound up the Grapevine, but I was doing an indicated 95 mph at the time. The Miata's fan also comes on at 207°F, but the drop in temp to 180°F was probably because of the lightened load on the engine once at the top, rather than the fan doing anything. If your fans did come on, then the FC thermoswitch definitely helped.

arghx

iTrader: (3)

the thermoswitch will activate at 207F but stay on until temperatures drop below about 195F