Sounds like a tired water pump....tell your mechanic to change it free of charge since he didn't test it and should have if he has thrown your engine away already.

__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k