Why did b-29 tail #26242 "esso express" have 1 silver engine and the rest body color?

Question

the 1 engine was just the cap

Answer 1

I have to agree with the others above me.  Changing engines on war time B-29s were common.  I have read that when General Curtis LeMay changed the bombing tactics over Japan to low level, the engines lasted longer.

Answer 2

Yeah, it was probably a recent transplant from another aircraft. The engine would have been identical to the other three, except for appearance. The plane's performance depends on it. Swapping engines was very common, along with any other needed part or assembly. Cannibalism still lives in the aircraft maintenance world.

Answer 3

Most likely the one silver engine was taken off another aircraft, but they didn't get a chance to paint it.