The other night my dumped coolant in a parking lot, i filled it up it leaked again, boiling from the overflow tank, then it stopped leaking, i drove up onto the highway it was fine for a few miles then shot towards the red on the gauge, i stopped, it hadnt leaked, it cooled i continued home at low speed around 35-40mph no problem, now if i drive around town its alright for about 15-20 miles then gets hot quickly, no leaks at all, the heater blows cold also, i checked hoses, thermostat works was replaced months ago, how do i check for fan clutch failure and also bleeder screw probs...