I'm doing a lot of work on my truck this weekend (See here), and one of the things I'm doing is installing a Mark VIII fan with a vsc controller.

I don't trust the Poke in radiator thermostat so I bought a VSC's coolant sensor accessory that gets piped into the cooling lines, but as I was prepping my replacement Intake plenum I had a brainstorm. The plenum I have is off an older model that had two temp sensors, where my truck only had one, so why not just use that hole for the coolant sensor?

The VSC temp sensor is too large to fit in the hole, but I've tested a dodge sensor and it runs in about the same resistance range as the VSC (about a max 1K ohm difference). Any reason this wouldn't work? or at least any reason not to try it?

 

You want the temp sensor for the fan controller AFTER the thermostat..... otherwise, it will simply run constantly, once the engine reaches operating temp.

 

fwiw, I trust the probe poked through more than other means, as you can locate it in a consistent and temperature precise area.. if you're going to do what you're going to do, I hope your controller is adjustable..

that said, you should work fine with what you're doing, so long as the signal sent from the sensor used is the same as the one expected.

 

Here I am testing resistance over different temperature ranges, and you come point out the obvious lol.

Thanks for pointing that out.

 

Controller is adjustable.

I guess my thinking is putting it in the coolant stream you are getting a measurement of the actual coolant temp. Maybe I'm just over thinking things though.

 

You want the temp sensor to pay attention to the temp of the coolant in the radiator... An IR temp gun is great for finding a good place to put it.

There are also the adapters that allow you to put the sensor in the upper radiator hose.

 

Yeah, I've got their kit that does that. But I'm starting to think maybe just sticking in the radiator probe is the simple option and I'm just over thinking things.

 

i'd want the sensor in the coolant itself as well.

 

where in the coolant itself?

your choices are limited.. you can put it coming out of the engine where it's too hot, or going back into the engine where it's cooled off.. or, you can shove the probe through the radiator (usually about half way up) where it is regulated and consistent- and the best place to trigger the fans if it gets too warm..

If you catch it coming out of the engine, you're overworking the fans because it hasn't had a chance to do the heat exchange yet.. If you catch it reentering the engine, you are playing from behind the eight ball already.. I've done it three different ways.. the radiator probe is the best for nice and consistent operation.. Using an IR Heat gun, you can quickly and easily find the sweet spot..

shoot the rad once the truck has reached operational temperature, such as parking it after driving a fair piece- moving above speeds of 35mph or so, there is no need for fans of any sort (if your cooling system is healthy).. park it after the truck has reached operational temperature and everything has stabilized, so to speak.. Pop the hood, shoot the rad until you find the temperature of your rated t'stat.. shove the probe through there.. it is generally about half way up the rad, it's been my experience..

put the fuse in the fan circuit, wait for it to fire up.. shoot temperature again, and adjust the controller (if it is adjustable) to come on at a touch above the rated temperature.. if the controller is not adjustable, move the probe toward the cool side until it fires a touch above the rated 'stat temperature..

by a long shot, I trust the probe over contact with the coolant... now, if I could somehow sample the coolant in the radiator with a contact probe, then I would be all for it..

 

My Jag uses the probe inserted into the fins of radiator and works well.

On mY Ram, my TCP controller uses the temp sensor in intake. It does not run all the time (unless I turn on AC - and it picks up signal from there) based on the "temp-on" value programmed into it. TCP has three presets loaded with the ability to load a custome setting. That said, it will depend on the type of controller.....but a simple "on-off" will proably have fan running all the time when engine gets to temp.