My cousin gave me a 75 hp Johnson (1983) which I am going to replace the 50hp motor on my fishing boat with. I got it started and running good and the only issue with it is the tilt/trim. One of the trim cylider seals was leaking slightly and it would not raise the motor. I got a seal kit and replaced all of the cylinder seals and made sure the unit was full of fluid on the bench when before I reinstalled. On the bench it extended fully with no problems however the lift cylindar would not retract. I installed it back on the outboard and thought maybe the weight of the motor would help and that it would just need a little bleeding. I got it to go down but now it will not lift it back up at all. The trim cylindars will raise it slightly but not fully without help and the lift cylidar is not lifting at all. With the trim cylindars extended it is holding up fine and does not settle but I have nothing on the lift cylinder stage. When I lower it the trim cyliders are now not going all the way down either. When I pulled the cyliders apart to put the seal kit in there was a little bit of sludge at the bottom of each cylindar that I cleaned out but not much and it seemed like pretty old dirty fluid. It has been sitting for several years. I never took the shuttle valve assembly or any of the check valves apart. I just replaced all of the cylinder seals. Is my problem a stuck shuttle valve or check valve? I've rebuilt tons of hydraulic cylinders but am not too familiar with these tilt trim units. With the cyliders fully extended I ensured it was properly full of fluid. With the trim cylinders exended it will hold and not settle but I can fully lift the motor by hand and lower it back down onto the trim cyliders without opening the bleeder on the side. It is not an easy lift though. There is plenty of resistance. The left trim cylider seems to want to lift and lower before the right cylinder does. Please advise......
