I have a mercruiser ( year 2000) bravo 3 outdrive which has 6 inches of play. All steering hydraulics inside the boat are tight and sound. The play is on the outside of the boat. Any ideas on what is wrong and how to fix it?
Sounds like you have a problem with the gimbal ring. There is a splined shaft that runs up the gimbal ring and connects to the steering arm that the steering cable hooks up to. Chances are the nut ontop of this shaft came lose a few years ago and the play just got worse as the years went on. You need to hope it did not wear the Gimbal ring away. Not a fun or cheap job at all if this is the problem.
Someone would have to look at the boat to give a price. Some boats have no room and the engine needs to be removed. Other's may require the whole transome shield to be removed also. Its a hard one to price without seeing it.