Trim/Tilt piston

[fishtails]

I recently replaced the seals on my 99, 100hp due to a leak. After replacing, the trim/tilt worked fine (would raise and lower and the engine would stay in place) but the engine would rise up out of the water when in reverse. I was told by my local marina that this was a valve issue. I cleared and replaced those. Now, the trim and tilt still works and will raise and lower the engine but when in the up position it will slowly drop and when I put it in the down position I can lift it. So, there is no pressure building up. I have bleed the system and filled with new fluid. Is this still a seal issue or is the piston shot?
Joe

[Michael j]

When you were replacing the valves was one of them
the Manuel release valve?

[fishtails]

Yes, the orginal leak was the dust seal, once I broke down the whole piston ( to replace the dust seal) I replaced all seals. No external leaks now, I have replaced the manual valve & seat hoping that was the issue. I have also replaced all the seals in both valve subassiblies & the piston shuttle valve hoping to solve the issue with no luck. It will trim up and down with out bleeding down but I can still lift it up ( no back pressure) at this point I think I may have an issue some where in the piston I rebuilt possible. I'm not sure where to go next any help would be greatly appriciated.

[rodbolt17]

drift up.
faulty down main valve.
faulty shock absorber valve.
faulty tilt piston bleeder valve.
faulty manual release valve.
faulty trim piston orings.
faulty tilt piston orings.
faulty two way check valve.
my suspects would be.
faulty down main valve,shock absorber valve,tilt piston bleeder valve, anyothers usually cause other issues as well.

[fishtails]

Thanks for the info, I have ordered tha parts hoping that will fix the issue. THANKS!