I’ve tried searching all over the internet for some answers but I have been unsuccessful. I have a 2003 Pilot with 251k miles (I know, a lot) and seemingly overnight it has developed a loud rattle/grinding noise when below 2500 rpm. At complete idle, there is no noise at all. And as soon as the engine hits 2600 rpm, the noise stops completely. The rattle/grind will get steadily louder all the way up until 2500 rpm and then stop like a switch was flipped. The sound seems to be coming from or around cylinder 1 (far left and back side of engine if you’re looking at it from the front of the vehicle), but it is difficult to pin point it exactly. The engine being hot or cold doesn’t effect this noise. The oil level of the engine was a little low but nothing crazy, topping off the oil did nothing. There is also no loss in power at any rpm while driving. I have no idea what it could be. I really hope this is not the beginnings of this engine giving out on me! Any help at all is greatly appreciated.