I just finished swapping the motor to my 03 Z. The car runs good but begins to overheat when I start driving. The temp gauge will climb very high. It goes back down to normal however when the car idles. Will having air in the cooling system cause this issue though or could it be something more? Is the best way to purge the system through the factory manual instructions? Thanks!

 

sounds like air to me. get coolant system checked and fixed ASAP.

 

^^^ this, agree.

 

I don't know if I should start a new thread but I have this SAME problem. My Z is stock, seriously all I did was put a drop-in K&N air filter in it. All of a sudden, tonight my car overheats and I guess goes into "limp mode" where the ECU cuts fuel and timing because the car started shaking due to the engine running really badly. I pulled over, shut it off, replaced the coolant with some distilled water to get it home. It ran fine on the 5 min drive home.

Now I have never even flushed the coolant on this car yet, was actually going to do it this weekend even tho I am doing it 5k miles early. They did it when I bought the car and I haven't even gotten 30k on it myself yet. I think my thermostat might have gone bad.

I sat in the car and let it idle and also did 2k-3k rpms for about 10 second intervals just to test and it stayed at 33%, exactly where the needle always stays as long as I have owed it. As soon as I go for a ride around the block it shoots up to H almost immediately, I get home pop the hood and coolant is coming out of the overflow.

Anyone have any ideas?