Looking for strange noises can be fun , one , what else have you changed since you got the car , could be some bearings in to water pump or alternator could be dry , fan belts can do the same thing , a/c clutch if you have it can do it too, try removing all the belt and try again , but only for a minute when cold to see if the noise goes away , if you have a automatic check the toque converter nuts and transmission lines to see if the are hitting anything , next could be the engine mounts are mushed out and touching somthing when cold , since you have the fan belts off change the timing belt , at that mileage it is going to snap , happy hunting