Hi, I've got a '56 F-100. The radiator is a stock style 4 row copper and brass unit. I have a 302 bored .040 and it's doing a good job, cooling it. I currently have a schroud I adapted from another radiator with a 14" electric fan. I had the fan wired up to a toggle switch, but was forgetting to turn it on, so I went a bought the Imperail model #226203 fan controller at Advanced Auto. I installed it set to turn on the fan at about 190 degrees and it works, in stop and go traffic it cycles the fan. But I notice after an open road run, it will not come on until about 215 degress! At that temperature, and with only a 7 pound cap (that is the warranty stipulation)coolant will expand into overflow. I currently have the sensor installed just inside the fan schroud,so it is just touching the radiator fins, at the upper middle portion of the radiator,where it would be just under the upper tank and inlet hose. I have been experimenting around with different locations, mounted it on the tank,just below the tank, just above where the schroud meets the tank, and now inside the schroud just about where the sensor would hit the top of the schroud. I am thinking after a road run the sensor cools off to the point, where it takes a while longer to get heated up again from the heat from the radiator. This kit has you mount the sensor on the radiator fins itself, and not poked through the fins. (Good thing as I just paid $400 for this new radiator,and I don't want to poke anything throught it!). The probe is about 5" long and the diameter looks to be too big to be poked through the radiator anyway. The instructions only say to choose an appropriate location for the sensor. It included a radiatormount zip tie, pads, and one of those rubber lined, "c" shaped, one screw hole, wire loom type mount, you are suppose to mount the temp sensor through to hang on the radiator. My question, where would be a better, appropriate location? Near the lower portion of the radiator? Middle? Or should I just junk this thing and buy a sensor you screw into the intake maniford or thermostat housing?

 

I have the same sensor as you, with similar results. BTW, that same kit is available at wildly different prices from different sources. I got mine a autozone for about $29. It is a better than nothing solution, but I still have my manual switch. I've found that after lots of fiddling to get the turn on temp just right, it may still not turn on sometimes. My sensor is mounted like yours, but it seems that if the truck is sitting still, no air flow over the sensor, the sensor doesn't properly read the temp until it's too hot. While moving it seems to work OK. I'm running a Spal fan, and I'll probably remove this system at some point and install the variable fan control that Spal makes. It has a sensor that screws into the water jacket of the head or intake manifold. It's alot more money, however.

 

Sounds like your doing what you should..experiment with different locations, ,..then after finding the best spot ..mount it.
Problem is finding the spot, you want it as close as possable to the highest temp heat source..that is probably at or near the upper radiator hose/radiator as the T-stat opens, and coolent starts flowing to the radiator.
Did you say the fan controller was adjustable?? that should help dial-in the operation.
Is your dash temperature gauge accurate?? Don't be afraid to zip-tie the new sensor in different locations during your test runs....keep a notebook on the seat and write down the results so that you do not forget them or confuse each seperate test run. An infra-red temp gun would come in real handy to verify results. I suspect alot can be learned with the infra-red temp gun at idle, right in the driveway. Also be sure that you have bled the cooling system of any air-pockets. Just some ideas.

 

There is nothing wrong with it hitting 215*, but if you don't like seeing that temp reset your controller a little lower, maybe 180*.

DeRale makes a nice adjustable controller that has a sensor that screws in were you want to put it, mine is in the lower tank and is adjusted per the temp gauge(and IR temp gun). It only sells for about $40 at Summit, if I remember right.

 

I hate the push in senders, they never read correctly. I have this set-up on my '47 flathead, always have the senders in water (all newer factory cars can't be wrong).
http://hotronicsproducts.com/product...fc32ab43921451

 

That would work but why spend $80 when you can get this for $44.

Derale Performance Deluxe Adjustable Controllers with Pipe Threaded Probes - SummitRacing.com

 

I personally don't like the adjustable ones, the rheostat still can fail. You buy the temp sender from Hotronics for what temp you want it to come on at. Also summit has a handling fee so it's only a $25 difference. You want the temp sender at the hottest point (or close to the hottest), like the intake or the head....remember the coolant flows from top of the radiator down, into the motor and out the thermostat.

 

I really appreciate all the responses!
Rhopper. It's nice to know that it's not just my unit or my install!
I have spent most of the day today working on this. And like Rhopper, I have come to the conclusion that with this style of unit (with the mount to radiator temp sensor) is sort of a "better than nothing" deal. I have tried multiple locations, re-calibrated the thermostat/switch. At about 5:00pm this afternoon, I had it working perfectly, I set it to go on at about 195, and it would trip off at about 180....all in stop and go traffic. It didn't miss a beat But tonight, driving again in stop and go traffic, it would work sporadically. The difference must be the air temperature. This afternoon it was around 65 degress, and tonight it's about 40. Since it's almost time to put it away for winter, I guess I'll just get by the way it is for now. and keep an eye on the temp gauge, and use the manaul switch if needed. But next spring, I'm going to look into the units you folks have suggested I look at.
I bought this unit at Advance Auto for around $18 plus tax, so at least I am not out alot! But still would of been nice to have that $20 to put in the gas tank!!

 

Hooler, I think that Derale unit looks like a good solution.

 

Thanks Rhopper! I will look at that one. Meanwhile I found something else that should work preety good. A 3/8" (includes a 1/2" adapter) screw in temp switch, that goes on at 195, off at 185. It's offered by Watson Street Works. It either comes in a complete kit (Part #SP-195FH)with relay, fuseholder, and temp switch for $59.00, or just the switch(part #SP-195TS) for $30.00. If I go this route, I'll probably just buy the switch, and screw it into the thermostat housing, where the old vacuum control ECT valve went.

<TABLE border=0 width="100%" align=center><TBODY><TR><TD vAlign=top width="90%">Radiator Fan Harness

This is the best "standard" Radiator Fan Harness we could find. Thermostat with 3/8-NPT thread, stainless steel 3/8-to-1/2NPT adaptor, connector, relay, relay socket with wire harness leads, fuse holder, fuse, the necessary hardware for installation and instructions. Turns ON at 195° and OFF at 185°. If you're putting in an electric fan, this kit will make it operate right.

</TD><TD vAlign=top></TD></TR></TBODY></TABLE>
<TABLE border=0 cellSpacing=2 cellPadding=1 width="100%" align=center><TBODY><TR><TD bgColor=#99ccff width="90%">#SP-195FH</TD><TD bgColor=#99ccff align=right>$59.00</TD></TR><TR><TD bgColor=#cccccc width="90%">195° - Thermostat only. #SP-195TS</TD><TD bgColor=#cccccc align=right>$30.00</TD></TR></TBODY></TABLE>
www.watsons-streetworks.com