Before a month i had my 230ce 88 model head done by expert mercedes mechanic.Now after a month i notice that there is excessive pressure in the water hoses.After a trip i parked the car and next day i checked it and there is still pressure and water came out when i opened the cap.I went to my mechanic and he told me it is normal,then i went to other mechanic and he told me there is something wrong.So what do you think guys?Is it normal to build pressure in the water system and remain the pressure on it after day???The temp gauge of the engine is not exceeding 80c and i dont have any overheating problems.