So I just did my clutch and everything in the coolant system was working fine before but I started it up for the first time and the temp gage went straight to hot and the fans kicked it up to high I tried to bleed it a little bit but couldn't get any coolant out of the top radiator hose bleed screw so I shut the car off and I'm a little nervous to let it run very long is it actually overheating or does it do that with air in the system?

 

Yes, it will do that with air in the system, also could be a stuck thermostat, but since everything was in order before, I'm leaning toward air.

One thing I like to do, is fill the tank and open the bleed screw, and just let it sit for a while to let the fluid naturally fill all the pockets instead of trying to force it. I do this a few times until I get fluid from the bleed screw without running the car.

 

I finally got the air out but still stays on hot even before I start the car if I just turn the key the fan kicks on and the temp gauge shoots up. I'm thinking something with the temp sensor I have to figure out where that's at

 

I always drain my system by taking a vacuum cleaner and sticking the end in the overflow tank. Open the bleed screw by the radiator and I can get almost 90% of the fluid out. When I refill, I separate the hose at the bleed screw, tilt the hose up a little and pour the antifreeze in. Once the radiator is about filled, reconnect, and then I use a funnel that has a straw taped in place. This fits in the bleed screw opening and I top it off. Start the engine and once the fluid starts to come out the bleed opening, I place the screw in. Never had an issue after at least 6 times doing this.

Remember that there is another bleed screw at the thermostat housing. If you remove the air cleaner box it is easier to access. AND remember you can set the large speedo inside the car to read the engine temperature. If this shows an immediate spike even with a cold engine, it would be logical to assume the temp sensor is faulty?

 

I think I may be of help. I just replaced several major parts on my 2004 r53, including clutch. I had the same symptoms after putting everything back together.

Fan running, heat pegged to the top, and one thing different was a/c

compressor not engaging. After hours of trouble shooting, turns out the

temperature sensor harness was not engaging 100%. When I dropped the

trans, the temperature sensor wire had to be disconnected. The locking clip on

the plastic harness broke in the process. I discovered the problem when I was

trouble shooting the temp sensor. Without a secure connection the ecu was

getting a false reading of overheating, thus the fan running constantly to cool

the engine, and a/c shut down due to false overheat reading. I taped up the

harness and zip tied it secure to temp sensor and everything is back to normal.

The temp sensor is right next to the thermostat.