I have a 2003 Nissan 350z and it won’t stop overheating. I’ve replaced the thbermostat with an autozone one and it still overheated and I found in the forums that those ones tend to not work because they have 2 dissimilar metals or something so I ran it without the thermostat for about 3 months and it worked fine but i wanted to be able to warm the car up and have heat in the winter time so i decided to try and replace it with a OEM thermostat about 3 days ago and made sure it was bled and was running fine until today….. it overheated again and was bubbling over the overflow reservoir. I have also done a pressure test and a head gasket leak test and it passed both of them. The only other things I can think of is the radiator and the water pump but the water pump doesn’t show any signs of failure and I have no idea how to tell if a radiator is bad or not. Please help!

 

Do you have a 6MT or Automatic?

Make sure the electric fan package is working. If you turn on the AC (Max cold), both fans should kick on, if they aren't turning on, something is wrong with the fans.

Make sure your engine coolant temp sensor is working properly, would need a scanner that can show live data for this.

Under what driving conditions is it overheating? Lot's of stop and go traffic or while cruising at freeway speeds or doesn't matter?

Do you have any obvious signs of a coolant leak? Is the radiator original? What color is the coolant? Also, does the overflow reservoir have a dirty brown film lining the inside walls?

Did you follow the FSM coolant fill and bleed procedure when you replaced the thermostat? (Did you crack the bleed port on heater hoses near battery firewall?)

-Icer

 

Even if the water pump appears to be working, it could be faulty internally (e.g. a broken blade). Check if it is generating enough circulation by opening the radiator cap with the engine running and checking if the coolant is circulating properly.

 

It seems you copied it from somewhere else.


 

A fix would be to not run the car more than a few minutes at a time. You're welcome 1 post user who never logged back in

 

You have a large air bubble in the system, almost 100% sure.. use a vacuum fill device and this will never occur again.

 

I love the vacuum fill tool! There are some vehicle specific caveats when using it, but I've had good success with it once I figured out how to properly prime it. Sadly, the user who started this thread has ghosted.
Cheers!
-Icer