Hello anyone. new guy here. Parents 1998 v70 base loses coolant and over heats. replaced ECT, thermostat, and coolant level sensor and the car still runs hot. The temp gauge goes to the middle, but my OBD shows a rise in temp. If I unplug my ECT the gauge stays in the middle. the only time my temp gauge spiked, was when the OBD showed 120 degrees C. Where is the temp gauge getting its info?

 

Not sure where it gets its reading but I think it's the ECT. The needle will lock in at 1/2 way when coolant reaches 172°, stay there until the temp reaches 240° at which point it will start to raise. The fan comes on at 216° and will shut off at 206° (I'm on my phone so you'll have to do the conversion).

The water pump system is very simple so you can replace the thermostat and/or water pump. If the car has been over heated, it likely has a bad head gasket.

 

https://www.youtube.com/watch?v=jsxPXltMFOc&feature=youtube_gdata_player