Okay so I have had my z somewhere between 2-4 months and have been noticing most of the time it runs fine but sometimes the gauge reads that it's running hot (but never at the top of the gauge at that point I would pull over and shut her off) it typically happens at stop lights or when moving slow but not all the time (in fact most of the time it's fine) but it also happens more when it's cold outside (temps in the say 40's or below) it's a bone stock (as far as I can tell, except a K&N cone air filter that was on it at time of purchase) 04 350z any ideas on what to look for? Also the heater isn't alwase hot often not much hotter than ambient air temp but will get nice and hot when running highway speeds and sometimes running city speeds but not normally. I'm thinking maybe thermostat but I honestly don't know no dash lights are on at all

 

you either have air in the line or bad tstat. when it get hot, pop the hood and touch both radiator hoses... if the bottom one is cold, it is the tstat

 

okay I'll check that out next time thanks man if air got in the line how would I go about getting it out? And do you know how bad it is to change the thermostat? Just by what I have experienced so far I'm think it is the tstat but haven't checked the hoses yet

update:
I checked the hoses after driving home from work both were hot must have air in the system

Update: I just got on my pc (was on my phones internet earlier) and searched on how to bleed Thanks again for your help bud!

 

could also be one or both of your fans. Sometimes the problem is intermittent.

Known issue so should be able to pull up threads to help diagnose.

Good luck

 

That^

Run the car with the radiator cap off and see if it bubbles or goes down after like 30 min of letting it sit on idle. Add coolant at times the fluid goes down. Cause that's air pockets.

Do this whole the engine is cold. Do not take the cap off of an already hot engine.

 

I bled it using the bleeder valve and topped off coolant and she's been staying nice and cool so far and I have heat at idle now too