Rebuilding the Engine in my 1928 Ford Model A.
The joy of maintaining an old car...
After many many miles of enjoyment, the engine developed a serious vibration.
After pulling it out and taking it apart, I found a failed weld on one of the weights used to counterbalance the crankshaft (an aftermarket add on for a smoother engine).
The excess vibration also caused a chunk of babitt to break off one of the connecting rods, further adding to the shaking.
A couple months and a couple thousand dollars later, I had it all cured and put back in the car.