Either your cooling system has not been bled or you have a greater problem (which caused high pressure and expansion tank to crack)
One possibility is that your water-pump impeller is loose and when under load (higher RPM), the impeller spins freely on the shaft.
It could also be that the thermostat has failed and is not opening/closing as it should. The red on the gauge means your damging you engine.
There is a reason why there is a sticky that tells you to replace the whole system on failure and not just the individual parts. You will spend more money on labour and bullshit trying to fix everything individually then had you just replaced it all.
Rain Sensor Retrofit: Here
Coupe Headline Replacement: Here
Last edited by jaymemaurice; 06-10-2012 at 03:26 AM.