Originally Posted by WAYNE88N/A

Since any different mounting location along the coolant flow paths are going to give you different readings, as alluded to above, there is no "normal" temp. Granted, we usually consider 180-190 normal, but that just happens to be right at the location of the thermostat, after the coolant has passed the hot combustion areas of the housings and is on its way back out of the engine. If we could somehow get our OEM gauges to read specific numbers from the point of the OEM sender location, the temps would be much cooler than at the t-stat housing, because the flow hasn't picked up the rotor housings' combustion area heat yet. In fact, if I'm interpreting this crappy picture of coolant flow paths in the FSM correctly, the coolant has just entered the engine and passed the intake & early compression stage portions of the housings, so it will be closer to radiator temps than actual thermostat temps. So, 140*F could actually be a "normal" temp at our OEM sender locations...

It really doesn't matter where it's mounted, as long as you have a good understanding of what the temps should be at that particular location. Anything wrong with the coolant system will show up as exaggerated temps, no matter what location the sensor's at, except maybe at the heater circuit mentioned earlier...Heck, even one mounted at the drain valve location at the bottom of the rad is going to give you an idea of how she's cooling once the t-stat pops...

Originally Posted by RETed

If the coolant passages are clogged (which I've seen it happen), then you have "erroneous" readings off the sensor.



-Ted