Having installed RealGauge, I'm able to get a precise temperature readout, which has always been just about 200 degrees. Car runs like a top, so I never give the temp a second thought. Last week, I changed my thermostat housing, which came with a new thermostat. I was surprised to find the car now runs a pretty consistent 185 degrees. Nice side benefit!

 

To me 185 sounds too low.

 

From JTIS, the design temperatures are the thermostat starts to open at 80°C (176°F) to 84°C (183°F) and is fully open at 96°C (205°F).

Presumably you have fitted a replacement thermostat which has a different operating range?

Keeping cool is good but running cooler than the design temperature sends an input signal from the ECT sensor to the ECM that the engine is not up to temperature.

Graham

 

There is enough tolerance in the design that 185 should not cause any problems with the ECM, though it does seem that either the thermostat (more likely) or the new temp. sensor (less likely) is slightly out of spec. It sounds as if it is running more like the Eurotoys low temp. thermostat which runs about 13°F cooler than stock.

 

Would deliberately tweaking our engines down to 185 degrees make temperature aged components like hoses etc last longer/become more reliable, I wonder?

 

It is probably closer to 190 most of the time, although it will rise to about 200 depending on conditions. So far, no issues.