2005 Yamaha F90TR 90HP Outboards Factory Service Manual, Page 189Get this manual
Bracket unit 2Check the operation of the absorber valve and check for dirt or residueClean if necessary
4Remove the bolt 3, then the tilt piston 4
Assembling the tilt cylinder
1Install new O-ring, the backup ring, and new dust seal into the trim cylinder end screw 22Install the O-ring onto the trim cylinder end screw
Checking the tilt cylinder and trim cylinder
1Check the power trim and tilt unit for cracks or corrosionReplace if necessary2Check the inner walls of the trim cylinder and tilt cylinder for scratchesReplace if necessary3Check the outer surface of the tilt piston and free piston for scratchesReplace if necessary4Check the tilt ram for bends or excessive corrosionPolish with 400- to 600-grit sandpaper if there is light rust or replace if necessary