So my woman's car is a 2004 350Z enthusiast model. (Non HR) and had over heated on her on her way home from work. Upon inspection I found a leak in her radiator, no big deal, replaced the thing. I also replaced the thermostat while I was at it, burped the cooling system like a new born baby and it still gets a little hot, it doesn't get up to overheating but it takes it a minute to go from normal operating temp to a little above and it seems to hold there for a while, I park the car before it gets much higher to prevent causing more work on my end. Also the heater core isn't pushing ANY warm air and that worked before I fiddled with it. Another thing I have noticed is the fans won't kick on. Even with the AC on full blast. I checked the fuse for the fan and it is intact. My mind is wondering if I didn't burp the system 100% correctly, the fans are dead and are causing that little bit of extra heat orrrrrr it's the water pump those are my only ideas.

 

these are notorious for air bubbles...

copy and paste this in google

proper cooling system bleeding site:my350z.com

 

I had the same issue and ended up replacing my fan motors. The motors are very cheap and interchangeable with a lot of other Nissans. I went to a salvage yard and pulled some off a low miles altima. While I was at it I changed the radiator, thermostat, radiator cap, and upper and lower hoses. Non of this was very expensive. I burped the system using a yellow funnel off amazon and some wheel ramps to get the radiator to the highest point. Made it easier.

Again my issue was the fan motors but easy piece of mind to do the whole system.

https://www.amazon.com/Lisle-24610-Spill-Free-Funnel/dp/B001A4EAV0

 

Is there a certain magic mileage number to be concerned with in regards to changing out your cooling system? My '05 is right at about 107k [original owner] and still has the OEM radiator, fans and thermo with no issues so far. Last time I took it up to my local shop for suspension work they told me that should probably be my next fix.
I'm usually of the opinion "if it ain't broke..." but if this is something I should be concerned with to save the longevity of my car's life I'd do it.

Just wondering...

 

I usually do the thermostat either at 100K or if it goes out obviously
Radiators crack from time to time, that's another part that you replace as needed. As for the coolant, I try to change and flush around every 40K

 

I think I would rather just go new on something like that. I'm all for salvage yard parts because why throw away something that works right? But electronics I try to go new. Also I live in Southern Idaho and 350Zs don't end up in salvage yards here. But I was thinking about replacing the entire fan shroud thank you for letting me know I can just replace the motors

 

Oh wow, thanks as well for stating that otherwise I wouldn't have known that myself.

 

I can almost bet you still have air in the system somewhere. The heater blowing cool is usually a strong indicator of that. Did you bleed the system with the front end raised? I tried bleeding it while my car was on the ground. Once I read the FSM, raised the car and followed the procedures it started blowing hot again.

If you don't have an FSM I believe I still have a digital copy lying around that I can send you later in the day. Can't hurt to follow it. As previously mentioned, our Z
s system is VERY difficult to bleed 100%