Hi guys my engine is over heating before u guys say its the head gasket let me explain no white smoke or dripping water coming out off the exhaust nothing in the oil, oil is black..the car pulls perfect i took it to a mechanic he had a look an there was some air traped so he got the air out everything was ok until the next day then it happened again he wanted to charge me £30 just for undoing a screw to let the air out but i didnt pay him as i had a feeling it will happen again did some research thought it might be the thermostat i changed it myself it wasn't that now i thing its the water pump i have to fill it up with water everyday as i know i have a leak by the water pump and there is this wird noise coming from the front it might be the fan but i dont think it is the fan any ways few days ago i filled it up with water then forgot to put the rediator cap on THE ENGINE DIDNT OVERHEAT :s every time i leave the cap off it wont overheat as soon as i put the cap on it overheats why is that??i just bought the car and to be honest i love it but if i change the water pump and that wont solve the problem then i will know its the head gasket which will cost me a lot i dont have much money to spend i got a kid to look after have to pay house rent....on top of that im a new driver the insurance is so expensive plus it fail the mot with a lot of problems (£450) now i know most of u will say what u still doing with this car (guess what i love the car) i need a car as i work night time i couldn't afford to pay £20 for a taxi every night(life is a B**** for some) i cant afford to buy another car so please please help thanks