If you thing it's coming from the front end take injector out cylinder 1 bar the engine just past tdc get a long thin Allen key or something that fits down the injector hole and press down on the piston if the piston moves down you have a small end issue but when checking its important you got by tdc so the crank is dragging the piston down the bore this will allow you to push it if there is a problem.
How is that engine so clean ? Lol