I got the answers regarding thermostat and water pump. The next assignment, and question is regarding coolant expansion tank cap.
How to test it, figure out when it's good and bad. 13 years old cap should be replaced or not? If it's sealed, it causes overpressure in the system and does not release the pressure, it does not hold the proper pressure and may overpressure the system. Without replacing not necessary parts, does anyone knows how to test it, if its good or not, it it holds the proper pressure and does not overpressure the system?