Mechanic gave a listen to the engine and has a thought.
Happens warm or cold above a particular RPM (around 1700 right now) Sound is not at the ends of the engine Middle/center deep sound (listened from bottom)
He thinks it is definitely a connecting rod.
Ugh...
If this is the mechanic that did your seal I'd stay away from him. He is going to drain your dry with little fixes.
Engine Test Stand Playlist: https://www.youtube.com/playlist?list=PLwoxyUwptUcdqEb-o2ArqyiUaHW0G_C88 restoring my 1968 Firebird 400 HO convertible (Firedawg) 1965 Pontiac Catalina Safari Wagon 389 TriPower (Catwagon) 1999 JD AWS LX Lawn tractor 17hp (my daily driver) 2006 Sequoia 2017 Murano (wife's car) 202? Electric car 203? 68 Firebird /w electric engine 2007 Bayliner 175 runabout /w 3.0L Mercuiser__________________________________________________________