i went to garage and he checked the car for any leakage, he goes there is a small leakage near the tank but it is a drip after abit of time other then that, he didn't find anything wrong. he said, engine works fine. he flushed all the coolant and took all the air out from the system and filled with fresh coolant.
i drove for half an hour and coolant light was came on, went back to the garage, he goes let it cool down and fill the water in again and see how long will it last over the weekend. if it goes quickly then we will go into depth of it. he goes to change the tank will be 70quid include the expansion tank price.
he goes, he kept the car running for an hour and did rev up as well but it didn't find any fault other then little drip from the tank.
as the coolant light came on, the heater start blowing cold air but i didn't let the car heat up.
other question, i bought a K-seal. shall i put it in the radiator? i asked the garage, he goes it is good but i wouldn't put in yet.