Electric Fans? Where is Your Sensor?
 

Hello All,

I'm trying to diagnose a cooling problem. I have the dual Spal fan set up on my DewItt's radiator. I'm using a fan controller. I'm wondering if I placed the sensor for the fans in the correct location? It is in the radiator hose attached from the radiator to the thermostat housing.

Where did you place your temperature probe or sensor in your electric fan installation?

Craig

Mine was in the passenger cylinder head when using the spal controller, was going to add another to the drivers head to run separate temps for each fan but then went to a PWM controller and now the sensor is on the rad itself, totally different setup
M

Mine is in the passenger side head. Same place for all my builds.

What kind of temperatures were you running with either set up M?

Big Block so your mileage may vary
On the high precision -easy to read stock temp gauge
195-205 in traffic with it in the head, seemed to let it get too hot before they kicked in and they had a hard time pulling it back down with the engine not turning over and air flowing so it would just drop a bit and hold it, never overheated by any means
never gets above about 185 with the PWM controller now, they start to come on much lower at a lower RPM
M

Interesting question. Have an LS3 and my setup came delivered with the sensor just under the steam line. Fans almost never come on while driving, but when I park the car, they tend to come on at idle. I haven't thought about why that might be.

Craig: Wouldn't your placement be the coolest part of your system. Mine would be pretty close to the hottest.

Mine more or less does the same, as long as i'm moving at a half decent rate there's enough air coming through the rad to keep it more or less within temp, but when I stop or am going in traffic /around town, there's just not enough air going through the rad to make much difference, plus all the air under the hood just sitting there doesn't help

This is my issue also M.
Runs about 195 regularly. When I drive in slower traffic it hits 210. Never hotter. But I don't like running that hot. Summer isn't even here yet.

Heat has been an issue I have fought. Ironic since I live in Alaska. Pushing 10lbs of boost so my combustion temps are high. My sensor is in drivers side head. dual spals come on @190. Temp holds there even while pushing the engine hard on an 80F day. My total solution was Methanol injection, DeWitts radiator, Dual SPAL.

Intake manifold next to thermostat housing. EZ-EFI 2.0

I don't know if it makes a difference but that's one of the absolute hottest positions and the position most likely to have steam pockets. Ideally would whatever position hits your trigger temp first be the best position?

I have mine in the intake manifold next to the thermostat housing as well. Been there for about a dozen years now. Works perfectly.

The maker of my fan controller says to put the temperature sensor in the outflow side near the bottom of the radiator.

Guess I'll try that next.

When I was scrounging the scrap yard looking for parts for my electric fan setup I noticed that BMW had sensors in that location.

Lets work off a few assumptions.... If the rad outlet is coolest and the inlet is hottest and your triggering off the outlet at 190 then whats the engine outlet temp? 200? 210? 220. I understand the logic of the lower outlet position but would think the upper inlet, being the hottest, would trigger the fans sooner. But as mentioned earlier, upper inlet has drawbacks, steam pockets and low fluid levels will throw things off.

This is all interesting to me as it relates but doesn't relate to my day job of operating the 'heart lung machine' which entails monitoring various water, blood and patient temperatures as well as gradients.

That's where my Derale sensor is, seemed really strange but somehow works perfectly (plus it's a surface mount rather than inserted into the rad or even a push through probe. I guess technology keeps moving on
https://cimg8.ibsrv.net/gimg/www.cor...78e3b7eec0.jpg
M

Gentlemen I think we have solution. I'm going to relocate my sensor and see what happens.

I have DPFI, and so the sensor in the head feeds the computer and it controls the dual spal fans.....

here is the trick though....like I have posted many times in these threads.....long time ago I noticed the smaller openings in stats that were rated 195f, 160 and 180 state had larger openings.....SO when the 195 stat opens the flow rate is less by design, today the 3 temps only control the opening temp, the FLOW RATE is the same as a 195f stat......so what need do is trim the skirts of the stat, OR drill holes in the skirt......

sure it takes a tad longer to warm up, so what?? maybe northern winter folks will need change stats with seasons......

Keep in mind that mine is a PWM controller and the sensor is for something like 160 to start the fans at %60 speed and then keeps adjusting them to maintain a certain temp so that's why they are monitoring at that location.
M

I run 2 sensors - one in the head 180* and one in the water neck 195* . If one fails the other will work.

Each sensor controls one fan. There are 2 fans and 2 relays.

Yes. Mine is an adjustable PWM controller from the AutoCoolGuy. Works on the same principle as yours.

https://cimg5.ibsrv.net/gimg/www.cor...f9cb86b4ef.jpg