I want to ask for advice before a start disassembling and diagnosing it, probably someone has had to deal with this and can give me some advice many to avoid overlooking something simple, by my reckoning most likely is a stuck thermostat but could be a leak or a failed water pump.The car is 605 2.1turbo diesel (XUD 11 ATE) this engine combo has been in my family for the better part of couple hundred thousands kilometers and is never overheated, coolant has been changed regularly and is less than