I purchased a short shaft water pump for the old fire truck(1959 261 six cyl) and now I can not get the fan clear of the crank at the bottom of the engine. I've got an sleeve that came with the pump but it still is real close. I'm using the four blade steel fan blade that is 18" in size. I'm looking at putting a washer inbetweeen the fan and fan blade. Anyone else have this problem? Help...