this is how i bleed the system i open it until there is a coolant coming out and i know there is no more air in the system plus the lower hose it hot and upper hose also. if the sleeve is cracked normally you should see some smoke coming out in the exhuast also in the downpipe between the turbo cuase i have that happen before. if the headgasket its possible cuase i went online to research and this kid have a similar problem and he said it did not show any smoke or anything. he replace it and fix the problem but i have a cometic not honda gasket. im gonna try to replace the thermostat cuase it could be sticking but i dont think thats the problem cause thats new also and aftermarket it would do the opposite on the gauge.i notice that if im overheating fan is not working but i bypass the sensor and put a clip to make fan running all the time and its still overheating.