the water pump bearing can sound like whole bottom end is knocking and the next likely culprit is flywheel cracked or loose bolts but a easy test is to remove belts and start up motor is noise still there or gone ,? if its gone start hand spinning pulleys by hand feel for grinding or resistence of the extreme the flywheel all you can do is inspect flywheel and the bolts that hold torque converter from inspection cover under car and please use jackstands or blocks to support anytime your under a car ,never trust a jack only situation youll lose every time