I've added a water temp probe in the upper radiator hose - is that the water returning from the engine, or going into it?

ahm

 

That's your return FROM the engine.

 

thank you much. so when people are talking about water temps, are they measuring before or after the radiator? ie, before (where my sensor is), or after the radiator (lower hose)?

ahm

 

Well, the Z's stock coolant temp sensor is at the very back of the motor, reading the water temp right as it's coming out of the engine. I'd want my sensor reading what's coming OUT of the engine, before going through the radiator. So you're good

It would be kinda cool to hook up two sensors; one on the incoming and one on the outgoing side or the radiator, just to see how efficient your radiator is, lol.

 

You are reading in the right spot.