Hi all,new here.I'm looking at a boat to purchase with a 75 HP merc. the owner took it to a marina,and they said they couldn't find the rattle in the engine.I asked,at what rpm it became significant...no answer so far. Could this be a piston wrist pin? How would I check for it if it is? Is a stethascope usable? Could I use a very small mirror in the spark plug holes to check for wall scoring? I don't want to buy it and listen to my wife whining because i bought a lemon. any help would be appreciated. thx Bob
