Hi all,
I am having an issue that no one seems to have an answer for. Hoping for some insight.

I got an 05 G35X Sedan AWD last October. It was my mothers car. Almost immediately I noticed that the cooling fan ran constantly, and it was ridiculously loud. I took it to the local Nissan dealer as there are no Infinity anywhere near me. I was told that this was “normal” and everything was fine. I live in the northeast. It gets really cold here in the winter. Fast forward a couple of months. The fan is still running high speed anytime the engine is running for more than 2 minutes.

I took it to a different Nissan dealer for an oil change in January. Once again I asked about the fan and was told that “it was normal”. I know that it’s not. After doing research I thought it was maybe a relay or the fan module. I talked to a local mechanic who said that it wasn’t a relay, it might be the module but it also might be the fan speed switch, or it might be nothing. No one seemed to think it was a big deal as long as the temperature didn’t get hot. I flashed it and it had shown a few codes but nothing related to this. One was for low voltage current (I had to get a new battery), a fuel system code- lean B1, and a transmission code for the manual mode switch/circuit.

Once again I took it to a third Nissan dealership. This time they noticed that the fan was screaming and decided to test the radiator and told me that it had a small leak at the top and I would need to replace it sometime in the future, that it wasn’t an emergency and I could drive it for a while and shouldn’t have any trouble. I was planning on having it replaced later this month. That was just a few days ago.

Today I went for a quick ride (maybe 3 miles) and right before I got home the temperature gauge maxed out, the service engine soon light came on and the car sputtered for a second. When I parked in my driveway it was smoking a little. There was antifreeze dripping down from near the radiator cap and from another hose. The reservoir is in between min and max level. I let it cool down, took the cap off and started it up. This time it took forever for the fan to turn on. Maybe 15 minutes, but the temperature was good. I put the cap back on and maybe 5 minutes later the temperature started rising to just under half but never went higher. At this point I am not 100% convinced that it is actually a cracked radiator.

I will gladly replace the radiator, or thermostat or water pump but I have no idea what the actual problem is. Any suggestions are very much appreciated.

 

Firstly, the fans will kick on high anytime the AIR CONDITIONER is turned on.

As for puking coolant, get a pressure tester (most local auto parts houses will "rent" one with only a deposit fee that you get back later). First test the cap, it should hold around 14psi, if it doesn't you need a new cap. Then test the radiator, don't pump it up more than the cap pressure, I think it's 14 psi but double check.

Now with the pressure on the system you can find the leak.

As for the relays, you have THREE cooling fan relays in the IPDM (engine bay fuse box behind battery). Personally I would just grab 3 new relays and swap them out if the fans turn on after the engine has been on for 2 minutes and the air conditioner is off. There's no way the engine has enough heat in it after 2min to kick on the fans. Personally I suspect your air conditioner is on though...

There is no fan controller on the V35 chassis, that replaced the 3 relays when they designed the V36 chassis.

For the future, NEVER let your engine temp hit the high mark on the gauge. You have a good chance of warping a head if you do, shut it down at 3/4 on the gauge if you have to. Let it cool off, then start up and drive again.

Probably what happened is you have been slowing losing coolant and haven't been topping it off. Don't rely solely on the reservoir, you need to occasionally be checking the radiator itself, personally I check once a month. It doesn't always drip on the ground either, sometimes it comes out as steam, sometimes it's just a slow dribble that accumulates on the bottom lip of the radiator and just evaporates before ever dripping on the ground.

After you refill the radiator get the engine up to temp and verify you don't have an air pocket in the cooling system. Turn the HEATER on max heat max fan and make sure it blows hot air. You can also use the heater to help cool the engine if you ever do start to overheat since it's just another small radiator in the cabin of the car.

 

Thanks for the help. The AC is definitely off. I also don’t have it on the defroster. I called the 3rd dealer that said that the radiator was cracked today. The tech said it absolutely 100% is cracked at the top and that’s why the fan is on. I believe him about the crack, I just don’t get the fan. Like you said it shouldn’t come on blasting high when it’s only been running for 2 minutes. It doesn’t even have a chance to warm up. I ordered a new radiator and will grab a tester to borrow tomorrow when I go to town pick it up.

The strange thing is that the temperature gauge went from below 1/3 (where it usually sits) to maxed out in about 3 seconds. Exactly at the same time the SES light came on and the car lost power. My eyes have been glued to that gauge since I heard that the radiator might be bad. This was maybe 100 feet from my house. I definitely didn’t drive it anywhere hot so I’m hoping that I didn’t screw anything else up. I think I’ll grab the relays too.

Thanks again