Having a little trouble with my controller for the Spal fan. It is one of the new controller that adjusts the speed of the fan. It seems that if the high and low value are to close it will only run on high when the high signal is reached. No fan when the low signal is reached. My problem lies in the gauge sensor in the head. When sitting at an idle it goes up very quickly. Over 220 but if I take a reading with an IR gun the water temp going back into the rad (measured at the thermostat)is only 185 to 190. My sensor for the fan is in the intake and the gauge sensor is in the head. It looks like I am really heating up at an idle according to the gauge but I am not really that hot. The headers seem to be heating it up quickly when idling. I am out of ports on the intake to try and mount the gauge sensor. The car runs cool when running at speed it never goes over 175 when running. So it seems the lack of airflow or something is heating the sensor up when I'm not really that hot. I know I'm rambling a bit here but I'm not getting good results with the fan controller running this way. Any thoughts?

 

I'd be suspicious of the gauge temp sender. In my small block, the sender was in the head and the gauge temperature was 22.5 degrees hotter than what the IR gun showed at the thermostat housing.

I just did a big block swap and mounted the same gauge sender unit in my big block, but this time on the intake manifold. Guess what? The gauge temperature still measures 22.5 degrees higher than what the IR gun shows at the thermostat housing.

 

You say the fan doesn't turn on at low speed? Perhaps that is why your temp climbs at idle, maybe you need more airflow through the rad at idle? Why do you suppose your fan doesn't turn on when the low point is reached? How easy is it to adjust the on points on that controller?

 

I know why the fan is not kicking on, that is what I'm working on. My question was about the temp differences from the outgoing water vs the temp gauge settings. The outgoing water checked with an IR gun is about 190 when the gauge reads 220. When running the gauge reads about 180 and the outgoing water reads about 175. It seems the head temp sensor is heating up very quickly but the actual water temp is not heating up to quickly.

 

Oh now I get it... Is that a stock temp sensor? Seems to be a tad non-linear eh?

Note to self: don't post on the forum until AFTER the extra large coffee...

 

Mine is running perfectly - I took it for a long run yesterday at low and high speeds and the Spals came on in the right steps.

I mounted the temp sensor (Standard TX43) in the passenger side head (I did need an adapter to go from the 1/2" pipe to 3/8" pipe) and used the harness/plug (green/black wires w/ 2 prong weatherhead connector) without modification. DON'T USE TEFLON TAPE, especially if you are using a one wire sender. I decided I wanted to just let the gauge have it's own sensor.

Another thing came to mind - you DID set the low / high with the fan(s) disconnected, didn't you?

To set my low/high (approximately 190/200) I watched the gauge and took temp readings all over the place (engine and radiator) during the process. My observations were similar to yours - temps are all over the place! I decided to use the gauge as my "guide" as it was pretty accurate for where it was measuring.

"seems the lack of airflow or something is heating the sensor up when I'm not really that hot" - I don't think so - the actual sensing is done at the probe IN the water and is not influenced by the outside air temp.

What fan(s) are you running?

You definately need to have all of the seals in place - if you don't, the Spals will suck air from around the corners better than any other fan I have used - essentially just recirculating it's own [hot] air. I'm sure other fans will behave exactly the same. This can definately be a cause for overheating when not moving.

 

I am using the sensor that Spal sent me now. It is the 2 prong one mounted in the intake. My gauge sensor is not stock. My AFR heads were drilled for the smaller type sensor. I looked high and low for a proper one. It might not be exact but it has been pretty close, I thought. The car never went over 190 with the stock setup. When the fan (single Spal 16 inch) is running it stays cool no problem. My problem has been turning on the low setting. When I set it at 160 low 195 high it works fine. If I try to set it at 175 low and 190ish high only the high setting works. I did set it with the fan disconnected, many times. I have an email into Britt at Spal and am going to call him today. I would like to fan to turn off when running at normal speeds (temp 175) and turn on about 180 low and 195 high.

 

What is your thermostat temperature?

 

Just my $.02 - the IR meter will read the outside temp, the gauge reads the actual temp of the coolant. A 30 degree difference would probably be normal in this case...

 

agree with z-man. Also I suspect you are seeing the hysteresis associated with the controller temp adjustments. When it's set for 190 and 170 the high fan speed can't turn off. The hysteresis is probably approx. 25 degrees. I suspect the head sensor(other than gauge temp) should only be used for radiator fan control when engine is off to control heat soak if you have aluminum heads and/or 195 degree thermostat. You can't use the intake manifold sensor to control the fans when engine is off; it will run your fans unnecessarily.

 

My problem is that the temp gauge runs at 170 under normal driving down the road. If I pull off and check with the IR gun the temp at the thermostat, hose and a few other places nearby it reads 170 to 175. If I let the car idle in the driveway the gauge reads about 220 and the area at or around the thermostat reads 190. I'm probably being to picky about this.

 

There's another post about IR guns; but they are an indicator of the approx. temp. The surface and material will affect the reading a lot. i.e. rubber hoses will be real bad because they insulate more; and reflective surfaces will be bad also. I'd trust whatever sensor is actually in the coolant. you can get an idea of how accurate your sensor is by putting it in boiling water(212 at sea level) and checking it . At the least you will be able to hunt down the reason for the error.

 

Not true. I have mine set at 190 / 200 and it works fine. Temp sensor in the head is idea for this setup.

 

I think I asked you this, you are using the black/green weatherhead wires and the white wire is to ground?

 

Yes, that's correct.

I also asked what you had for a thermostat (degrees).

 

180 degree thermostat. One of the high flow units.

 

That's what I'm running - great setup!!