Okay so I think it’s my thermostat hi I have a 2005 g35 coupe and on the dash the temp reading is accurate when I start the car up as it says it’s cold and it warms up fine but every now and then like once or twice a day the car starts overheating but there’s no other indications of it overheating other than on the dashboard and it takes shutting off the car for it to make it go back down but that only started today before the temp gauge would randomly go up and back down but it would never cross below the half way mark which is operating temp so does anyone know what I need

 

So the needle never goes higher than the halfway mark? That doesnt indicate overheating.

 

hi so sorry I think I said it wrong I meant when it’s acting up it only goes above operating temp and then returns to operating temp but it’ll never drop below operating temp unless when it’s starting up and it’s cold

 

How far up above operating temp does it go? Does it do it very fast or slowly?

 

Generally, when engine is cold, temperature should climb and rest just below halfway on the temperature gauge, or just below flat needle.

If you start it again, after engine is warm, temperature should never go past the just below temperature gauge mark.

Anything above that mark, then engine cooling system is fighting something or temp sensor is intermittent.

 

Just confirming shurer's comment ... one tick below horizontal flat needle is where my temp gauge sits when all is hunky dory.

 

Ok. I'd like to add my question to this thread. As it is related..

My gauge stays where everyone above is mentioning it should be. Just below level.. BUT.. My cooling fan is almost always running. . Once its up to the mark, the fan comes on and stays almost 90% of the time. Even with the AC / defrost turned off.

I have fresh coolant and a new 170 deg F thermostat as I did a flush and fill during a Revup to non Rev swap I just did. I used a vacuum fill system to fill the coolant.

Looking at the FSM it shows the following:


Is it just that there is no mechanical fan on the front of the motor, that its relying on the constantly running electrical fan to keep it at temp? Do I just get used to the noise of the fan running, or should it actually cycle on and off?

The guys in the southern US where it get crazy hot, does your fan run constant, or does it cycle on and off?

I was worried at first about a possible head gasket leak, as the non rev motor I got is a JDM pull out.. But it came with no documentation.. They did say it had good compression @ 180psi, but I did have some liquid or heavy condensation in the right side exhaust when I first started running it.. The first few runs of the motor, my coolant level did drop, but lately it hasn't really moved since. And we have had quite a few 40 deg C (104F) days since and the temp level stayed solid as mentioned above..

 

I live near Dallas and it's hot. My 07 coupe fans do run a lot when the temps are high. I just replaced both fan motors when I noticed the fan cooling my A/C condenser was not working at all. The temp. gauge kept creeping up beyond the normal mid point.