I just bought a boat and motor. Its a 1957 Evinrude 18hp. The first time I had it out somebody said I should change the water pump. He said as a precaution he always changes the water pump. That dosent make sence to me but since Im new to boating I thought I would ask. What Should I do if the motor appears to run ok. It does sputter in idle but It has been sitting for 4 years so I thought running it might help that some. I will be taking it out for 5 days on the 4th. I did change the lower unit oil last month.I also changed the spark plugs yesterday. I kept the old ones just in case it runs worse with the new ones.