Let me try to sum this up with the least amount of cunfusion: 
I got my coupe last December. At that time it used the factory coolant temp gauge (seemed to work fine). Later, I installed an aftermarket mechanical temp gauge, seemed to work fine too, reading 190.
I installed a fan controller two weeks ago, all's good.
This past week, I took the water temp gauge out and replaced it with another mechanical Jegs gauge to go in my gauge cage in the AC vent. It went to 240! Freaked me out. It didn't seem to be that hot, when a motor gets to 240+, things start smelling and smoking, none of that. I took the tstat housing off to check the tstat, there wasn't one!
So I put in a good (checked it in a pot of water) 180 stat. Still went to 240 with the jegs gauge.
So I reinstall the first gauge, just mounted it temporarily under the hood and ran it up to the cowl, it reads 190 like it always did.
So I get a pot of water, put it on the stove and heat it to boiling, and with a known calibrated thermometer, I (carefully) take it outside and put both mechanical temp gauge probe ends in. They both read ~200F, which is good
So both gauges seem to be working accurately when submerged in a pot of hot water, but the jegs gauge goes nuts when it's installed in the manifold.
I know this is confusing, but is there some trick or something I'm missing in the installation of the Jegs probe? I see it has a rubber o ring, the first one did not.
Any suggestions advice is welcome.
I got my coupe last December. At that time it used the factory coolant temp gauge (seemed to work fine). Later, I installed an aftermarket mechanical temp gauge, seemed to work fine too, reading 190.
I installed a fan controller two weeks ago, all's good.
This past week, I took the water temp gauge out and replaced it with another mechanical Jegs gauge to go in my gauge cage in the AC vent. It went to 240! Freaked me out. It didn't seem to be that hot, when a motor gets to 240+, things start smelling and smoking, none of that. I took the tstat housing off to check the tstat, there wasn't one!
So I put in a good (checked it in a pot of water) 180 stat. Still went to 240 with the jegs gauge.So I reinstall the first gauge, just mounted it temporarily under the hood and ran it up to the cowl, it reads 190 like it always did.
So I get a pot of water, put it on the stove and heat it to boiling, and with a known calibrated thermometer, I (carefully) take it outside and put both mechanical temp gauge probe ends in. They both read ~200F, which is good
So both gauges seem to be working accurately when submerged in a pot of hot water, but the jegs gauge goes nuts when it's installed in the manifold.
I know this is confusing, but is there some trick or something I'm missing in the installation of the Jegs probe? I see it has a rubber o ring, the first one did not.
Any suggestions advice is welcome.
