Has anyone used a push in style rad probe on their FB? I mounted and installed a new aluminum rad+spal efan and purchased this kit: http://www.jegs.com/i/Derale/259/167...rentProductId=

It seems to be a little off. I spent the day troubleshooting the wiring to come up with what seems to be an unresponsive probe.

The engine stays cool on the highway, (on the 2nd "cold" bar ) But seems to never heat up the probe enough to switch on the fan. It now only gets hot sitting still in traffic, or low speed cruising. I've let it sit running for a while just to see if I could get the fan to switch on, but no joy.

Today I let it heat up past half on the gauge, and that seemed hot enough for me.

Any experience or knowledge on using these push in probes would be appreciated.

 

Usually push-in probes come with a resistance dial, so you can adjust when the fan kicks in. Is yours pre-adjusted to a specific temp?

I wonder if you can test the probe itself. Not sure if they're water safe, but if they are, perhaps put it into water and heat it up, and see if that kicks the fan on. Or heat the probe up with something else.

 

According to Summit the Derale 16738 (your kit) kicks on at 180 and shuts off at 170. So either the kit isn't installed properly/faulty or the car really isn't getting hot enough to kick the fan on.

http://www.summitracing.com/parts/DER-16738/

1. Check your wiring etc.
2. Use a secondary temp gauge i.e. infrared thermometer and see just how hot the engine really is at "1/2 way".

 

It's the same one I'm using. It has worked fine for me for 2 years now. Have you re-checked your wiring to make sure the harness is installed properly?

 

I have a 35 dollar advanced auto fan switch it has a small potentimeter to adjust the temp it kicks on. In my instructions it told you how to diagg a faulty probe. Iill find them and. See if you can get it figured out.

 

My fan comes on if I lead the two wires leading into the probe (switched 12v + relay yellow wire). Which would indicate the wiring is fine, but the probe will not complete the circuit. Right?

If I lead power through the green AC override wire, the fan kicks on regardless of switch position, but if I lead the two wires leading into the probe together the ignition switch must be ON to turn on fan.

Seems to me the wiring is fine, but my probe just isnt doing anything. The car has an aluminum rad in it now that keeps the engine at around the second cold bar when at freeway speeds, but sitting in traffic it heats up past the middle of the temp gauge.

I have not gotten it to complete the circuit yet, and im afraid to let it get so hot that it overheats just for the sake of turning the fan on.

Also, 210* is the hash mark on the gauge a little right of center of the gauge, according to the FSM translation. My car gets close enough to that to warrant 200* running temps, and at those temperatures the engine barely holds an idle, and runs extremely rich. Its also very hard to start after letting it go to that point. 210* is too hot for a thermostatic switch thats supposed to open at 185* NOT to even begin to turn on the efan.

 

Where on the rad did you mount the probe? You want it as close to the water inlet for the rad as possible.

That said, yours does seem to be staying off hotter than it should.

You can test it by putting the probe part of the switch in boiling water, and checking if it starts conducting using an ohmmeter.

If it won't turn on in 212* water, it's not working right.

 

I should preface by saying I can see both sides of this argument, but I would like to argue this point.

The radiators job is to cool down the coolant, correct? The fan supplements the radiator when then heat exchanging capability of the radiator is exceeded, correct? Thus, do you want the fans kicking on every time hot water comes INTO the radiator BEFORE the radiator has a chance to do it's job and cool the water down? Or, would you prefer to have the fans kick on when the coolant temperature exceeds the ability of the radiator to keep it cool?

So, for the next part, lets all agree that the water coming into the radiator is (in theory) always hotter than the water coming out. Thus, the fan will more easily turn on due to the constant hot water coming out of the engine versus occasionally coming on due to the cooler water going back into the engine because the radiator has had a chance to cool it first. I personally care more about the temp of the coolant going back INTO the engine than the temp of the coolant coming OUT of the engine (I already know water coming out is hot).

Now, the obvious argument is that if the fans are running because hot water is coming out of the engine, then it's assumed cooler water is going back into the engine. Could be. But what if the radiator gets obstructed (inside or outside) and the water going back into the engine isn't any cooler than the water coming out of the engine? What if you have no flow at all? If the fans were already on because of the hot water going in before the radiator had a chance to do anything, would you notice the water coming out was still just as hot?

Not to mention the fact that if the fans are running prematurely because of the hot water, the engine is potentially seeing thermal shocking by taking water in that's possibly overly cool because it has been through the radiator AND fans, versus the minor change it would see by slowly cooling the water via the outlet temperature. The engine being built of aluminum and cast iron expands and contracts at quite different rates, so thermal shocking might be an important thing to keep in mind.

That all said, I have ran the probe at both the inlet and the outlet and I prefer the outlet. The fan cycled too much on the inlet for my taste, and the temps seem to be more stable at the outlet.

~T.J.

EDIT: Cliffnotes - Thermostat should regulate your MINIMUM temperature, the fans should regulate your MAXIMUM temperature.

Also, as seen in the installation manual under troubleshooting for that kit:

 

For the purposes of troubleshooting the OP's problem (fan not turning on with higher engine temperatures), moving the probe closer to the highest-temperature point on the rad, which is at the radiator inlet connection, would help him determine if the probe is working or not.

For normal operation, with a probe that goes on at 180* and off at 170*, you'd want the probe near the outlet side of the rad. The engine's t-stat will close off if engine coolant temps get too low anyway, bypassing the rad.

Which is completely nonsensical, and contradicts what you just said regarding your own experience, where the fan was cycling too often (ie, turning on too SOON) if the probe is too close to the inlet.

I suspect a typo in the instructions, there.

 

I also read that twice and was still going . The closer the probe is to the outlet, the hotter the temp exiting the thermostat before the fan would kick on. So your engine would be running hotter the whole time, followed by a later, hotter fan kick-on temperature than usual.

If your thermostat is 180 (OEM) and your probe is 180 and is on the outlet, it would kick on right when your thermostat lets coolant out to the radiator if set right. This would keep the engine extremely cool, potentially, and I don't believe that it would cause the coolant to cool to the point where the thermostat would no longer let coolant out to the radiator.

If your probe was at the outlet of the radiator, the temp of coolant coming into the rad could be 200+ deg F before the fan kicks on because the probe is at the outlet reading 180 deg F.

It's a user preference, thank God it's still a mostly free country. I'm constructing my own research on the topic right now so I'll be posting a thread up of the coolant temps of clutch fan versus e-fan.

 

Did some playing with some expensive toys. My rad's care temp is around 40* cooler from on side to the other, moving the rad prob to directly UNDER the inlet resulted in the fans kicking on for the first time at 190*.

Still late, and my laser temp gauge confirms the little probe exceeds 200* ambient heat before it completes the circuit.


It's defective, nothing more to it.

 

Yep; and now you know by how much and in what way it is borked, which makes for a stronger case for warranty replacement.

 

Probe replaced, problem solved.

It comes on normally now, and the efan easily controls the engine temp.

I was told this engine had "bad water seals" by a local shop. Seems funny that it doesnt smoke/consume coolant AND with a working cooling system maintains an average 140* running temp.

 

This is why i prefer the ones with probe to go inside the radiator hose. I also heard some peeps using a honda fan fan switch but details not avail.



Temp gauges wise. There is approx 30-40 degrees difference between temp with cap tube installed in back of water pump and the heater hose outlet

 

[QUOTE=wankel=


I was told this engine had "bad water seals" by a local shop. Seems funny that it doesnt smoke/consume coolant AND with a working cooling system maintains an average 140* running temp.[/QUOTE]

people like that give us tech's a bad name! go back and slug him in the nuts whoever told you that!