1987-1993 Mercury Mariner Outboards 70/75/80/90/100/115HP 3 and 4-cylinder Factory Service Manual, Page 316Get this manual
Power Trim Partial Leak Down at Maximum Trim Power Trim Date Code 14182 and Below Service Bulletin No94-13Some units, when trimmed to the maximum 20 degree limit, will leak down approximately degrees and then holdThe leak will ONLY occur while the boat is under powerThe cause for the degree leak down is the lack of fluid passage between the shock piston and the memory piston1Disassemble the tilt ram assembly and remove the memory piston2Cut small groove 0.020 0.040 in(0.5 1.0mm) deep across the top face of the memory pistonThe groove will allow oil passage when the shock piston and memory piston are in contactThe groove can be made with hacksaw or triangular fileNOTE: Power trim assemblies with Date Code 14183 and ABOVE have groove in the shock piston to allow fluid passageThe memory piston remains the same and does not have groove across the face