Mecury 75 Tilt/Trim Problems

[rmaskell]

Last year I winterized my outboard following the Seloc manual and left the motor in a vertical position for the winter months. I covered everything up and brushed the snow off it several times during the winter. When I came to start it up this year I noticed that the Tilt/Trim ram had split over the winter. I ordered in a new outer casing for the Tilt/Trim ram. I pulled off the old one ( by removing the top of the electric motor and popping the two pins out) and took it into the Marine shop where I purchased the new ram housing. They installed the new ram housing and gave it back to me. I installed the fixed Tilt/Trim unit and hooked up the electric motor and refilled the fluid according to the procedure they gave me. I tested the Tilt/Trim out of the water and it worked fine. I launched the boat and tried the Tilt/Trim and again it worked fine. I then accelerated the boat and tried to trim it and the motor would come up and the go right back down. I tried several times but as soon I tried to trim the motor when going fast the motor goes a little bit up but drops down to the lowest point of travel. Any Ideas? Also how would water get into the Tilt/Trim ram assembly?

 

[rritt]

Last year I winterized my outboard following the Seloc manual and left the motor in a vertical position for the winter months. I covered everything up and brushed the snow off it several times during the winter. When I came to start it up this year I noticed that the Tilt/Trim ram had split over the winter. I ordered in a new outer casing for the Tilt/Trim ram. I pulled off the old one ( by removing the top of the electric motor and popping the two pins out) and took it into the Marine shop where I purchased the new ram housing. They installed the new ram housing and gave it back to me. I installed the fixed Tilt/Trim unit and hooked up the electric motor and refilled the fluid according to the procedure they gave me. I tested the Tilt/Trim out of the water and it worked fine. I launched the boat and tried the Tilt/Trim and again it worked fine. I then accelerated the boat and tried to trim it and the motor would come up and the go right back down. I tried several times but as soon I tried to trim the motor when going fast the motor goes a little bit up but drops down to the lowest point of travel. Any Ideas? Also how would water get into the Tilt/Trim ram assembly?

You probably rusted up the pump guts. Oil doesn't expand when cold so your cracked ram was result of water. Rusting of trim spool is a recurring problem on 91-09 Mercs. Rust and water causing hardening of check valves is universal. Depending on year you may find a rebuild service cheaper than a replacement - check ebay, amazon, and google.