Overheating

I had the same problem on my 2006 M35X. My radiator had a small leak near the top in the plastic. I didn't see it right away, and the easy/cheap thing to do was to replace the thermostat. I bought an aftermarket thermostat at Advanced Auto. It fit perfect, but hot top hose and cold lower hose. Car overheated after 1 block. No heat in cabin. Tried to bleed and fill, no joy. I eventually had to take it to my mechanic to figure it out. He spent 15 hours trying to bleed and troubleshoot. He checked water pump and flow through the radiator. He even put in another thermostat, same problem. He eventually put a Nissan thermostat in and fixed the problem. It looks like there is some diverter plate in the Nissan part that caused it to behave differently. $500 dollars in labor to figure out the third party thermostat doesn't work even though it fits. USE A NISSAN THERMOSTAT!!!!!!

I’m having this same problem right now and my car is at the mechanic. I’m thinking that the radiator needs to be purged due to air bubbles or the thermostat I have is absolutely horrible and I bought a thermostat directly from the Infiniti dealership.

GuruX2SST what was the part number for that Nissan thermostat that you used for you m35

Ok me and my son has been working on his infinity m35 year 2007 all day put a new radiator and thermostat on it because the radiator the top of it had cracked so it blowed fluid every where so we got that put back in and filled it up with antifreeze and water just like we were supposed to and bleed it by taking the cap of and it still running hot and no heat. What iam i missing. Can anyone help me please and thank you very much.

Similar issue on a 2014 Q50 that overheated. We tried an aftermarket thermostat and housing and it pressured up until it started spewing from the overflow in front of the rad cap. Turns out the Infiniti parts guy said there is a built-in pressure relief on the dealer part, a "jiggle valve" that allows the excess pressure to flow through. the aftermarket does not have it. Installed a dealer housing and t-stat and it worked!