Just got this boat. 1992 90hp merc. Tilt and trim seems to work ok in that it it trims up and down, when it gets to the down position it takes a couple of bumps with the trim control to get it all the way down, then when the boat gets up on plain I can trim the motor up to get the best ride and performance , but the trim wont hold I have to keep triming the motor up about every 15- 20 seconds to keep the mortor trimmed properly. In other words if I trim it up the motor slowly eases back down. I think there must be air in the hydro lines, but not sure. If it is air in the lines , not sure how to bleed the trim unit. Any Ideas?
