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Looking for a place to insert my probe......

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Well, I have turned to the dark side. I am abandoning my beloved 13-blade fan for good and installing a 16" Permacool electric fan. I know, I know, in past posts I have berated the use of an electric fan but now things have (or will) change. Since I am raising my compression and have to deal with headers, the stop and go driving in town will take it's toll on my water temperature. My problem is, because I am installing a puller fan (and replacing the hub with a machined disc) I want a place to insert my temperature probe so that I can work automatic as well as use a manual override. The wiring is not the issue. I will just follow Dan Masters' diagram. But I refuse to insert a probe in between the radiator fins. How about this one?: there is a little known and rarely used coolant plug on the right rear of the engine block. What a great place to insert a threaded temp probe! Just gotta figure out what the temp of the coolant will or should be in this area of the jacket and get the appropriate probe. Make sense. Does anyone out there see why this would not work. My other options are tee into the right side of the thermostat housing and run a probe with an appropriate pipe tee with a threaded probe or put a pipe tee inline with the top radiator hose (more room for leaks) or have the radiator shop braze in a fitting into a longer necked radiator inlet pipe from the same top hose. I plan to suitable wires, relay and fuse and have the thing mounted on the dash with indicator light (like I did my overdrive). Any wrong thinking here?

Bill
 
Bill,

I've been told that the best place to put a temp probe is on the bottom of the radiator or bottom hose.

Here's a pic of mine. The radiator shop charged $75.00 to fix this up for me, but if I had to do it all over again I'd use J-hooks to hold the radiator in place. I believe that would give you more room. The sensor is at the very bottom in the middle kinda hard to see... this was before the final coat of paint went on obviously.

normal_IMG_0312.JPG
 
The solution I had for my Spider was to use a couple of electric tie strips. I put one around the top and one around the bottom of the probe, then clipped the ends to about 1". I then pushed the plastic ends into the fins until the probe was flush with the radiator. Did this about 5000 miles ago...no problems.
 
I've also been told that the best place is the bottom hose. My buddy and I talked about him welding a threaded bung into the steel lower connecting pipe that will accept a temperature probe. Just have to make sure that it's oriented in such a way so that it's not hanging down and potentially get hit by some road debris. Originally I had though of having a fitting brazed into the rad itself, but it's far cheaper to replace that pipe if you screw up than the rad, and easier to get out and work on. Haven't really pursued this all yet as this project is lower on my list right now.
 
[ QUOTE ]
But I refuse to insert a probe in between the radiator fins.

[/ QUOTE ]Why? That's exactly what I did over 2 years ago with my PermaCool setup. Works flawlessly, and makes for a much simpler install. Also, I was able to put the sensor in the bottom of the top third of the radiator for optimum temperature control. I would not put it at the bottom because you want the fan to cycle based on the incoming water temp, not the outgoing. You risk overheating with the sensor at the bottom.

If you go with the NPT threaded sensor, put it in the upper rad hose.
 
car makers put the thermocouple at the bottom of the rad.they have a lot of engineering geniuses make these decisions. a few points to consider:
-a submerged location in the fluid is the most consistent,accurate and reliable location.there are no external factors to affect the probe.
-the buttom of the rad is least likely to have air bubbles or pockets to influence the reading.the top of the rad or engine can.(correct me if i'm wrong)
-stuffing the probe externally can be affected by air temperature at extreme temperature.i would block off the airflow with a 2" aliminum tape patch in front of the probe to get more consistent readings.
-bottom of rad or bottom hose next to the rad, set probe temp to suit.i think factory guys go here also so that temp INTO engine is not too cold.
 
Shannon,

Your electric fan installation appears very clean. I am interested in how you attached the fan to the radiator. Could you post close up pictures of this area of the assembly, including the radiator sides? Also, what did you mean about using "J-hooks"?

Thank you.

Alan
 
Shannon,
The install looks good, but. The top bracket sits right in the path of the strap brace that stabilizes your radiator. How did you circumvent this problem?
If I can't figure this one out, then I might rotate the whole thing 90 degrees and custom bend some relatively thin galvanized strap material and short-pop rivet the strap into the side of the radiator housing and , and....shoot, I don't know.....I like this big fan, I have the alternator and battery to push it, but mounting it is an enigma. Tell me that top piece isn't in the way.

Bill
 
Bill,

If I had it to do over again, I would do this (courtesy of Geo Hahn)...

fan8.JPG



As far as the way I did it, the brazed on brackets pushed back the fan a little too far, so I had to "massage" the cross brace to fit. You're right about the radiator brace being in the way, but I took a dremel and notched out a little metal and it bolted right up. I think if I had used the j-hooks, I would have eliminated these problems.

I the future sometime, I plan to cut off my custom fan mounting brackets and use the hooks. I'll then buy a used cross brace to make it right again.

Give me a few minutes and I'll go out to the garage and take a pic of the finished product.
 
Bill, If you did want to use that particular plug location, I would suggest for safety/accuracy to temporarily wire up another temp gauge just like the current one (TR4-6). Take readings for both from cold to hot conditions (might be interesting to do it before and after your performance upgrades) and then determine what temperature thermocouple/switch to install.
Tom Lains
 
Shannon,
I think I saw some dirt on one of your screws on your engine.

Bill
 
I'm not as big of a nut as it may seem... it's only been 1500 miles since the rebuild/engine bay repaint. Give me a little time to get it dirty!!!

/ubbthreads/images/graemlins/smile.gif
 
I use a early model thermostat housing that has the squared off flat spot. I drilled and taped for the sensor. It is easy to do--works perfect and is a sanitary factory looking set up. Be careful with the drill angle and tap.
 
If you spend a little more on an adjustable switch you can put the probe just about anywhere. One came with my electric fan.
 
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