Re: us force hydraulics
bottom line:
you need a valve body rebuild. If your engine is 1988 or younger then smart money is to get both motor and valve body serviced as a unit. They usually break within a year or two of each other.
low fluid it stops lifting when the pump runs dry but stays without any bleed down.
a leak leaves puddles in your garage/driveway and makes oil spills at the dock.
a valve body that needs rebuilding will lift engine and slowly drift down. At first it appears to stop when it gets to trim cylinder. This is becasue of differences in geometry and pSI requirements. So a lot of people falsely assume there is something wrong with tilt ram. As time passes it drops more and more rapidly until it finally drops faster than you can get boat onto trailer.
What year is your engine?
valve body rebuilds vary from $120 (89-92) to $180 (1970 w/ 1/2" bore).
If your engine is 1987 or earlier then you can try putting in new check valves
you'll need to pull pump off boat to get at rear check valve.
http://www.crowleymarine.com/parts/F17620.cfm
