I've got a sound coming from somewhere that I can't figure out. 455 mystery motor/TH400. The sound could be rod bearings but it seems to only occur at a certain RPM under load. I can't make it happen or hear it when I rev the motor when I'm under the hood. My past experiences with spun rod bearings is that when you rev it, it knocks as it winds down. My other possibilities are the torque converter or an exhaust leak.
What are the symptoms of bad rod bearings? The motor was "rebuilt" by person's of dubious skills (I got it cheap). The oil pressure isn't great at idle when hot.
If the knock developed after your last oil change or after you installed the motor and broke it in, I have found that if I have really shredded a rod bearing, I will find bearing material in the oil.
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI
Good point, You can strain the oil through a paint filter and look for bearing material and pull your filter then take it apart and look for debris between the paper folds.