[tracyrip]

does anyone know the difference between A4 and and A5 crankshaft on a mercury 225 3.0

[papasmurf]

Not really sure. You might try calling Mercury Marine, I'm sure they could tell you.

[NEECAPRS]

Tracyrip,Just in case you don't have an answer yet,in '98 Merc changed the style on 3.0 center main bearings from the in-line traditional twin row, loose rollers to the same single row, caged rollers that OMC has used all along for the 90 degree loopers. As such, those newer crankshafts don't have the separating hub in the center of each center main journal. The newer design is a much tougher crankshaft with still plenty of bearing. The older crankshaft was obviously the product of tremendous conflict beween the designers and the manufacuring department. It has sharply notched grinding reliefs on both sides of each journal, yet still has a total of four center main journals. In pairs, these journals need to finish up with absolutely no runout. So... both departments lost!