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Electric Fan sensor probe question

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jerrybny

jerrybny

Jedi Knight
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Has anyone ever heard of a probe which fits into a radiator hose, where the wires are thin enough to pass under the hose clamp without leakage. And if so where can I find a source for them. I've got my electric fan mounted as a puller and am now trying to decide how to mount a thermal probe. I'm not keen on putting a probe thru the radiator. Its a leak waiting to happen. Where does everyone who has a electric fan have their thermal probes mounted.
 
I do not use one, but would think the best location would be on the radiator outlet or lower hose since the temperature of coolant coming out of the radiator would be what determines if the fan is needed.

I have seen a probe strapped to an outside of a hose but don't know how well that works.
 
Jerry,
My probe is 3/8" NPT so I got a piece of stainless threaded pipe (threaded on the inside) and cut it and contoured it to fit snugly over my lower stainless return pipe. I drilled a hole in the return pipe, just so, where the sensor would thread into this bung and reach inside the pipe the correct amount to sense the temp and not impede the flow. Had a welder TIG the two stainless pieces together. I then grounded the body of the sensor back to the frame. Works very well.

Bill
 
On my probe, I used a couple of electrical straps to make "brackets", trimmed all but about 2" off the "tails" and then pushed the tails between a couple fins. Did that 2 years ago, and no problems here.
 
Hi Jerry,

The temp probe/thermoswitch for my TR4's elec fan is basically the same as Bill's, a bung welded to the lower radiator pipe and a probe that threads into it.

An alternative to this is a T-connector that goes into the radiator hose, but the hoses on my car aren't that long and make sharp angles. It's basically the same idea, but doesn't require any welding, just cutting a section out of the hose to insert the connector.

Yes, there are sensors that slip under the end of a radiator hose. I'm not wild about the idea, too likely to leak or plow the hose off, or crimp the sensor with the hose clamp, for my tastes.

I'm also not all that thrilled about the type that just slip into the radiator fan or otherwise attach externally. Ambient air temps have to mess around with the accuracy of this type. I'd much rather the sensor detect coolant temperature, as directly as possible.

You can get the varous types of sensors at www.summitracing.com, either as part of a complete wiring kit or as individual parts.

Cheers!
 
Bill,
What brand probe are you using. My return pipe looks like its plain ole metal not SS like the Moss catalog shows. So I plan to order a new lower SS pipe since mine is all rusty anyways. Now I suppose I could get a bung welded onto the SS pipe and mount my probe there. See any problems with this idea. I don't have the facalities to fabricate anything so I will be using the local radiator shop to do the work. Thanks
 
Jerry,
The probe I ended up using was the one that came with my Spal fan. It is a stainless steel probe with a large barrel shaped sensor tip. Any other would work fine. Actually, the bung I used is just plain ole steel and not stainless. My downpipe is stainless. That is why I used a good welder, someone who would weld a steel piece to a stainless piece, without burning a hole in my pipe (something I would have done). You just need access to a hacksaw and a bench grinder to shape the bung. Just make sure that after you contour it to fit the pipe, and cut the hole in the pipe, that the sensor extends enough into the path of the water without going too far in or not far enough. Trial and error. Then, after all is welded, I ended up needing to run a hardened tap with NPT threads into the finished product to clean up the few burrs and splatter on the threads for the sensor to seat. I just used a very narrow hose clamp to tighten against the sensor as a ground back to the chassis. If you can't get it done there, send the new pipe and sensor down here and I will get my welder to fix it up for you.

Bill
 
Bill thanks for the offer. I just might take you up on it. I have a 14 inch Hayden fan mounted as a puller. I went to the Spal site and it looks like I can use model #185FRH. It turns the fan on at 185 and off at 165. Since I only drive the car in the late spring thru early fall I use a 160 degress thermostat so I figured the 185/165 range is good. Please let me know if you see a problem with this. I appreciate you willingness to help out. Its not often that you run into people like you. Except on this forum of course. If all looks good to you I can see if my local radiator guy can mount the probe on the ss pipe. If not then I will probably take you up on your offer. Once again thanks a million. Can't wait for spring. Starting to get TR6 withdrawal pains from not cruising for 2 months.

Jerry
 
Jerry,
The Spal sensor is very good but pricey! I needed a stainless sensor because of my aluminum radiator (brass and aluminum don't mix). Other probes are just as effective, and tend to be shaped more like a "probe". Either way. I would recommend the Spal fan as they are exceptionally well made and the 16" model fits perfectly within the confines of a TR6 radiator. Now, I removed my stock fan and use a "higher horsepower" fan. Spal makes a very cool 16" fan that is low profile and would work well with the stock fan in place. The offer to fix up you sensor is good. My welder fiend would do for you the same favor as he did for me. Let me know. Maybe you could buy me a Coke or coffee some day. The booze is 21 years and counting.

Bill
 
The thermoswitch for my electric fan is about the size of a 10 cent stack of pennys and has spade terminals on one end and a half inch x 6-24 threaded stud on the other.

It is preset to turn ON at 180F and OFF at 160F.

On the underside of the top radiator tank of my big Healey, there is a OD threaded port with an ID threaded brass capnut.

I got a sugar cube size (.5"x.5"x.5") piece of square copper rod and threaded it 6-24. I then soldered it to the brass cap on the radiator port.

I screwed on the port cap, threaded in the thermoswitch (shortening the stud so as not to bottom), and hooked up the electrics.

I used a relay to connect to the fan and added a DPDT - Center-off switch so that I could force the fan either ON or OFF.

I've been running it for 5 years and it works fine.

Tim

Thermoswitch1.jpg
 
I mounted my Hayden sensor in the thermostat housing. I used a early model housing that has a cut flat area on one side, I drilled and taped for the sensor but you have to be carful to get it stright. Im a little bias but I think this is one of the most sanitary ways to go, it has also worked really well--fan coming on when it is supposed to with no problems. There might have been a model with a housing set up for a sensor because I bought an early model housing for an extra off ebay and it came with the hole drilled and taped--it looks factory.
 
The local radiator repair shop says he can put a bung on the radiator for a sensor. Does anyone see any problems with this approach? Bill I know you used the lower radiator pipe for yours. I'm just wondering why no one seems to get it mounted to the radiator. Thanks
 
The bottom tank is a perfect spot to install a sensor. If you have a radiator shop that will do it, so much the better. See if you can get him to install a drain valve while he is at it. Triumph didn't put any in.

Bill
 
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