Hi all, I have 08’ G37s coupe and currently dealing with an issue & could use insight from you guys. Over the past few weeks my fan won’t blow hot air at idle only when in motion; also my engine erratically overheats especially at idle. My coolant also goes down fairly quick, I brought it to one mechanic who thinks it’s the water pump and he saw some leaks near the water pump area. However I understand that our water pump is internally mounted so my question is could it be another possible issue such as the thermostat, etc. I’d rather consider all options before forking our the money since it’s a labour intensive job. Any advice helps thanks!

 

Sounds like it's the water pump.
But why not replace the much cheaper, and relatively easier to change out, thermostat first?
And I wouldn't keep keep putting it through overheating cycles!

 

I would check thermostat and see if radiator might be clogged